Merge branch 'devel-2.1'

[ganeti-local] / lib / cmdlib.py

#
#

# Copyright (C) 2006, 2007, 2008 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Module implementing the master-side code."""

# pylint: disable-msg=W0201

# W0201 since most LU attributes are defined in CheckPrereq or similar
# functions

import os
import os.path
import time
import re
import platform
import logging
import copy
import OpenSSL

from ganeti import ssh
from ganeti import utils
from ganeti import errors
from ganeti import hypervisor
from ganeti import locking
from ganeti import constants
from ganeti import objects
from ganeti import serializer
from ganeti import ssconf
from ganeti import uidpool
from ganeti import compat
from ganeti import masterd

import ganeti.masterd.instance # pylint: disable-msg=W0611


class LogicalUnit(object):
  """Logical Unit base class.

  Subclasses must follow these rules:
    - implement ExpandNames
    - implement CheckPrereq (except when tasklets are used)
    - implement Exec (except when tasklets are used)
    - implement BuildHooksEnv
    - redefine HPATH and HTYPE
    - optionally redefine their run requirements:
        REQ_BGL: the LU needs to hold the Big Ganeti Lock exclusively

  Note that all commands require root permissions.

  @ivar dry_run_result: the value (if any) that will be returned to the caller
      in dry-run mode (signalled by opcode dry_run parameter)

  """
  HPATH = None
  HTYPE = None
  _OP_REQP = []
  REQ_BGL = True

  def __init__(self, processor, op, context, rpc):
    """Constructor for LogicalUnit.

    This needs to be overridden in derived classes in order to check op
    validity.

    """
    self.proc = processor
    self.op = op
    self.cfg = context.cfg
    self.context = context
    self.rpc = rpc
    # Dicts used to declare locking needs to mcpu
    self.needed_locks = None
    self.acquired_locks = {}
    self.share_locks = dict.fromkeys(locking.LEVELS, 0)
    self.add_locks = {}
    self.remove_locks = {}
    # Used to force good behavior when calling helper functions
    self.recalculate_locks = {}
    self.__ssh = None
    # logging
    self.LogWarning = processor.LogWarning # pylint: disable-msg=C0103
    self.LogInfo = processor.LogInfo # pylint: disable-msg=C0103
    self.LogStep = processor.LogStep # pylint: disable-msg=C0103
    # support for dry-run
    self.dry_run_result = None
    # support for generic debug attribute
    if (not hasattr(self.op, "debug_level") or
        not isinstance(self.op.debug_level, int)):
      self.op.debug_level = 0

    # Tasklets
    self.tasklets = None

    for attr_name in self._OP_REQP:
      attr_val = getattr(op, attr_name, None)
      if attr_val is None:
        raise errors.OpPrereqError("Required parameter '%s' missing" %
                                   attr_name, errors.ECODE_INVAL)

    self.CheckArguments()

  def __GetSSH(self):
    """Returns the SshRunner object

    """
    if not self.__ssh:
      self.__ssh = ssh.SshRunner(self.cfg.GetClusterName())
    return self.__ssh

  ssh = property(fget=__GetSSH)

  def CheckArguments(self):
    """Check syntactic validity for the opcode arguments.

    This method is for doing a simple syntactic check and ensure
    validity of opcode parameters, without any cluster-related
    checks. While the same can be accomplished in ExpandNames and/or
    CheckPrereq, doing these separate is better because:

      - ExpandNames is left as as purely a lock-related function
      - CheckPrereq is run after we have acquired locks (and possible
        waited for them)

    The function is allowed to change the self.op attribute so that
    later methods can no longer worry about missing parameters.

    """
    pass

  def ExpandNames(self):
    """Expand names for this LU.

    This method is called before starting to execute the opcode, and it should
    update all the parameters of the opcode to their canonical form (e.g. a
    short node name must be fully expanded after this method has successfully
    completed). This way locking, hooks, logging, ecc. can work correctly.

    LUs which implement this method must also populate the self.needed_locks
    member, as a dict with lock levels as keys, and a list of needed lock names
    as values. Rules:

      - use an empty dict if you don't need any lock
      - if you don't need any lock at a particular level omit that level
      - don't put anything for the BGL level
      - if you want all locks at a level use locking.ALL_SET as a value

    If you need to share locks (rather than acquire them exclusively) at one
    level you can modify self.share_locks, setting a true value (usually 1) for
    that level. By default locks are not shared.

    This function can also define a list of tasklets, which then will be
    executed in order instead of the usual LU-level CheckPrereq and Exec
    functions, if those are not defined by the LU.

    Examples::

      # Acquire all nodes and one instance
      self.needed_locks = {
        locking.LEVEL_NODE: locking.ALL_SET,
        locking.LEVEL_INSTANCE: ['instance1.example.tld'],
      }
      # Acquire just two nodes
      self.needed_locks = {
        locking.LEVEL_NODE: ['node1.example.tld', 'node2.example.tld'],
      }
      # Acquire no locks
      self.needed_locks = {} # No, you can't leave it to the default value None

    """
    # The implementation of this method is mandatory only if the new LU is
    # concurrent, so that old LUs don't need to be changed all at the same
    # time.
    if self.REQ_BGL:
      self.needed_locks = {} # Exclusive LUs don't need locks.
    else:
      raise NotImplementedError

  def DeclareLocks(self, level):
    """Declare LU locking needs for a level

    While most LUs can just declare their locking needs at ExpandNames time,
    sometimes there's the need to calculate some locks after having acquired
    the ones before. This function is called just before acquiring locks at a
    particular level, but after acquiring the ones at lower levels, and permits
    such calculations. It can be used to modify self.needed_locks, and by
    default it does nothing.

    This function is only called if you have something already set in
    self.needed_locks for the level.

    @param level: Locking level which is going to be locked
    @type level: member of ganeti.locking.LEVELS

    """

  def CheckPrereq(self):
    """Check prerequisites for this LU.

    This method should check that the prerequisites for the execution
    of this LU are fulfilled. It can do internode communication, but
    it should be idempotent - no cluster or system changes are
    allowed.

    The method should raise errors.OpPrereqError in case something is
    not fulfilled. Its return value is ignored.

    This method should also update all the parameters of the opcode to
    their canonical form if it hasn't been done by ExpandNames before.

    """
    if self.tasklets is not None:
      for (idx, tl) in enumerate(self.tasklets):
        logging.debug("Checking prerequisites for tasklet %s/%s",
                      idx + 1, len(self.tasklets))
        tl.CheckPrereq()
    else:
      raise NotImplementedError

  def Exec(self, feedback_fn):
    """Execute the LU.

    This method should implement the actual work. It should raise
    errors.OpExecError for failures that are somewhat dealt with in
    code, or expected.

    """
    if self.tasklets is not None:
      for (idx, tl) in enumerate(self.tasklets):
        logging.debug("Executing tasklet %s/%s", idx + 1, len(self.tasklets))
        tl.Exec(feedback_fn)
    else:
      raise NotImplementedError

  def BuildHooksEnv(self):
    """Build hooks environment for this LU.

    This method should return a three-node tuple consisting of: a dict
    containing the environment that will be used for running the
    specific hook for this LU, a list of node names on which the hook
    should run before the execution, and a list of node names on which
    the hook should run after the execution.

    The keys of the dict must not have 'GANETI_' prefixed as this will
    be handled in the hooks runner. Also note additional keys will be
    added by the hooks runner. If the LU doesn't define any
    environment, an empty dict (and not None) should be returned.

    No nodes should be returned as an empty list (and not None).

    Note that if the HPATH for a LU class is None, this function will
    not be called.

    """
    raise NotImplementedError

  def HooksCallBack(self, phase, hook_results, feedback_fn, lu_result):
    """Notify the LU about the results of its hooks.

    This method is called every time a hooks phase is executed, and notifies
    the Logical Unit about the hooks' result. The LU can then use it to alter
    its result based on the hooks.  By default the method does nothing and the
    previous result is passed back unchanged but any LU can define it if it
    wants to use the local cluster hook-scripts somehow.

    @param phase: one of L{constants.HOOKS_PHASE_POST} or
        L{constants.HOOKS_PHASE_PRE}; it denotes the hooks phase
    @param hook_results: the results of the multi-node hooks rpc call
    @param feedback_fn: function used send feedback back to the caller
    @param lu_result: the previous Exec result this LU had, or None
        in the PRE phase
    @return: the new Exec result, based on the previous result
        and hook results

    """
    # API must be kept, thus we ignore the unused argument and could
    # be a function warnings
    # pylint: disable-msg=W0613,R0201
    return lu_result

  def _ExpandAndLockInstance(self):
    """Helper function to expand and lock an instance.

    Many LUs that work on an instance take its name in self.op.instance_name
    and need to expand it and then declare the expanded name for locking. This
    function does it, and then updates self.op.instance_name to the expanded
    name. It also initializes needed_locks as a dict, if this hasn't been done
    before.

    """
    if self.needed_locks is None:
      self.needed_locks = {}
    else:
      assert locking.LEVEL_INSTANCE not in self.needed_locks, \
        "_ExpandAndLockInstance called with instance-level locks set"
    self.op.instance_name = _ExpandInstanceName(self.cfg,
                                                self.op.instance_name)
    self.needed_locks[locking.LEVEL_INSTANCE] = self.op.instance_name

  def _LockInstancesNodes(self, primary_only=False):
    """Helper function to declare instances' nodes for locking.

    This function should be called after locking one or more instances to lock
    their nodes. Its effect is populating self.needed_locks[locking.LEVEL_NODE]
    with all primary or secondary nodes for instances already locked and
    present in self.needed_locks[locking.LEVEL_INSTANCE].

    It should be called from DeclareLocks, and for safety only works if
    self.recalculate_locks[locking.LEVEL_NODE] is set.

    In the future it may grow parameters to just lock some instance's nodes, or
    to just lock primaries or secondary nodes, if needed.

    If should be called in DeclareLocks in a way similar to::

      if level == locking.LEVEL_NODE:
        self._LockInstancesNodes()

    @type primary_only: boolean
    @param primary_only: only lock primary nodes of locked instances

    """
    assert locking.LEVEL_NODE in self.recalculate_locks, \
      "_LockInstancesNodes helper function called with no nodes to recalculate"

    # TODO: check if we're really been called with the instance locks held

    # For now we'll replace self.needed_locks[locking.LEVEL_NODE], but in the
    # future we might want to have different behaviors depending on the value
    # of self.recalculate_locks[locking.LEVEL_NODE]
    wanted_nodes = []
    for instance_name in self.acquired_locks[locking.LEVEL_INSTANCE]:
      instance = self.context.cfg.GetInstanceInfo(instance_name)
      wanted_nodes.append(instance.primary_node)
      if not primary_only:
        wanted_nodes.extend(instance.secondary_nodes)

    if self.recalculate_locks[locking.LEVEL_NODE] == constants.LOCKS_REPLACE:
      self.needed_locks[locking.LEVEL_NODE] = wanted_nodes
    elif self.recalculate_locks[locking.LEVEL_NODE] == constants.LOCKS_APPEND:
      self.needed_locks[locking.LEVEL_NODE].extend(wanted_nodes)

    del self.recalculate_locks[locking.LEVEL_NODE]


class NoHooksLU(LogicalUnit): # pylint: disable-msg=W0223
  """Simple LU which runs no hooks.

  This LU is intended as a parent for other LogicalUnits which will
  run no hooks, in order to reduce duplicate code.

  """
  HPATH = None
  HTYPE = None

  def BuildHooksEnv(self):
    """Empty BuildHooksEnv for NoHooksLu.

    This just raises an error.

    """
    assert False, "BuildHooksEnv called for NoHooksLUs"


class Tasklet:
  """Tasklet base class.

  Tasklets are subcomponents for LUs. LUs can consist entirely of tasklets or
  they can mix legacy code with tasklets. Locking needs to be done in the LU,
  tasklets know nothing about locks.

  Subclasses must follow these rules:
    - Implement CheckPrereq
    - Implement Exec

  """
  def __init__(self, lu):
    self.lu = lu

    # Shortcuts
    self.cfg = lu.cfg
    self.rpc = lu.rpc

  def CheckPrereq(self):
    """Check prerequisites for this tasklets.

    This method should check whether the prerequisites for the execution of
    this tasklet are fulfilled. It can do internode communication, but it
    should be idempotent - no cluster or system changes are allowed.

    The method should raise errors.OpPrereqError in case something is not
    fulfilled. Its return value is ignored.

    This method should also update all parameters to their canonical form if it
    hasn't been done before.

    """
    raise NotImplementedError

  def Exec(self, feedback_fn):
    """Execute the tasklet.

    This method should implement the actual work. It should raise
    errors.OpExecError for failures that are somewhat dealt with in code, or
    expected.

    """
    raise NotImplementedError


def _GetWantedNodes(lu, nodes):
  """Returns list of checked and expanded node names.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type nodes: list
  @param nodes: list of node names or None for all nodes
  @rtype: list
  @return: the list of nodes, sorted
  @raise errors.ProgrammerError: if the nodes parameter is wrong type

  """
  if not isinstance(nodes, list):
    raise errors.OpPrereqError("Invalid argument type 'nodes'",
                               errors.ECODE_INVAL)

  if not nodes:
    raise errors.ProgrammerError("_GetWantedNodes should only be called with a"
      " non-empty list of nodes whose name is to be expanded.")

  wanted = [_ExpandNodeName(lu.cfg, name) for name in nodes]
  return utils.NiceSort(wanted)


def _GetWantedInstances(lu, instances):
  """Returns list of checked and expanded instance names.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type instances: list
  @param instances: list of instance names or None for all instances
  @rtype: list
  @return: the list of instances, sorted
  @raise errors.OpPrereqError: if the instances parameter is wrong type
  @raise errors.OpPrereqError: if any of the passed instances is not found

  """
  if not isinstance(instances, list):
    raise errors.OpPrereqError("Invalid argument type 'instances'",
                               errors.ECODE_INVAL)

  if instances:
    wanted = [_ExpandInstanceName(lu.cfg, name) for name in instances]
  else:
    wanted = utils.NiceSort(lu.cfg.GetInstanceList())
  return wanted


def _GetUpdatedParams(old_params, update_dict):
  """Return the new version of a parameter dictionary.

  @type old_params: dict
  @param old_params: old parameters
  @type update_dict: dict
  @param update_dict: dict containing new parameter values, or
      constants.VALUE_DEFAULT to reset the parameter to its default
      value
  @rtype: dict
  @return: the new parameter dictionary

  """
  params_copy = copy.deepcopy(old_params)
  for key, val in update_dict.iteritems():
    if val == constants.VALUE_DEFAULT:
      try:
        del params_copy[key]
      except KeyError:
        pass
    else:
      params_copy[key] = val
  return params_copy


def _CheckOutputFields(static, dynamic, selected):
  """Checks whether all selected fields are valid.

  @type static: L{utils.FieldSet}
  @param static: static fields set
  @type dynamic: L{utils.FieldSet}
  @param dynamic: dynamic fields set

  """
  f = utils.FieldSet()
  f.Extend(static)
  f.Extend(dynamic)

  delta = f.NonMatching(selected)
  if delta:
    raise errors.OpPrereqError("Unknown output fields selected: %s"
                               % ",".join(delta), errors.ECODE_INVAL)


def _CheckBooleanOpField(op, name):
  """Validates boolean opcode parameters.

  This will ensure that an opcode parameter is either a boolean value,
  or None (but that it always exists).

  """
  val = getattr(op, name, None)
  if not (val is None or isinstance(val, bool)):
    raise errors.OpPrereqError("Invalid boolean parameter '%s' (%s)" %
                               (name, str(val)), errors.ECODE_INVAL)
  setattr(op, name, val)


def _CheckGlobalHvParams(params):
  """Validates that given hypervisor params are not global ones.

  This will ensure that instances don't get customised versions of
  global params.

  """
  used_globals = constants.HVC_GLOBALS.intersection(params)
  if used_globals:
    msg = ("The following hypervisor parameters are global and cannot"
           " be customized at instance level, please modify them at"
           " cluster level: %s" % utils.CommaJoin(used_globals))
    raise errors.OpPrereqError(msg, errors.ECODE_INVAL)


def _CheckNodeOnline(lu, node):
  """Ensure that a given node is online.

  @param lu: the LU on behalf of which we make the check
  @param node: the node to check
  @raise errors.OpPrereqError: if the node is offline

  """
  if lu.cfg.GetNodeInfo(node).offline:
    raise errors.OpPrereqError("Can't use offline node %s" % node,
                               errors.ECODE_INVAL)


def _CheckNodeNotDrained(lu, node):
  """Ensure that a given node is not drained.

  @param lu: the LU on behalf of which we make the check
  @param node: the node to check
  @raise errors.OpPrereqError: if the node is drained

  """
  if lu.cfg.GetNodeInfo(node).drained:
    raise errors.OpPrereqError("Can't use drained node %s" % node,
                               errors.ECODE_INVAL)


def _CheckNodeHasOS(lu, node, os_name, force_variant):
  """Ensure that a node supports a given OS.

  @param lu: the LU on behalf of which we make the check
  @param node: the node to check
  @param os_name: the OS to query about
  @param force_variant: whether to ignore variant errors
  @raise errors.OpPrereqError: if the node is not supporting the OS

  """
  result = lu.rpc.call_os_get(node, os_name)
  result.Raise("OS '%s' not in supported OS list for node %s" %
               (os_name, node),
               prereq=True, ecode=errors.ECODE_INVAL)
  if not force_variant:
    _CheckOSVariant(result.payload, os_name)


def _RequireFileStorage():
  """Checks that file storage is enabled.

  @raise errors.OpPrereqError: when file storage is disabled

  """
  if not constants.ENABLE_FILE_STORAGE:
    raise errors.OpPrereqError("File storage disabled at configure time",
                               errors.ECODE_INVAL)


def _CheckDiskTemplate(template):
  """Ensure a given disk template is valid.

  """
  if template not in constants.DISK_TEMPLATES:
    msg = ("Invalid disk template name '%s', valid templates are: %s" %
           (template, utils.CommaJoin(constants.DISK_TEMPLATES)))
    raise errors.OpPrereqError(msg, errors.ECODE_INVAL)
  if template == constants.DT_FILE:
    _RequireFileStorage()


def _CheckStorageType(storage_type):
  """Ensure a given storage type is valid.

  """
  if storage_type not in constants.VALID_STORAGE_TYPES:
    raise errors.OpPrereqError("Unknown storage type: %s" % storage_type,
                               errors.ECODE_INVAL)
  if storage_type == constants.ST_FILE:
    _RequireFileStorage()


def _GetClusterDomainSecret():
  """Reads the cluster domain secret.

  """
  return utils.ReadOneLineFile(constants.CLUSTER_DOMAIN_SECRET_FILE,
                               strict=True)


def _CheckInstanceDown(lu, instance, reason):
  """Ensure that an instance is not running."""
  if instance.admin_up:
    raise errors.OpPrereqError("Instance %s is marked to be up, %s" %
                               (instance.name, reason), errors.ECODE_STATE)

  pnode = instance.primary_node
  ins_l = lu.rpc.call_instance_list([pnode], [instance.hypervisor])[pnode]
  ins_l.Raise("Can't contact node %s for instance information" % pnode,
              prereq=True, ecode=errors.ECODE_ENVIRON)

  if instance.name in ins_l.payload:
    raise errors.OpPrereqError("Instance %s is running, %s" %
                               (instance.name, reason), errors.ECODE_STATE)


def _ExpandItemName(fn, name, kind):
  """Expand an item name.

  @param fn: the function to use for expansion
  @param name: requested item name
  @param kind: text description ('Node' or 'Instance')
  @return: the resolved (full) name
  @raise errors.OpPrereqError: if the item is not found

  """
  full_name = fn(name)
  if full_name is None:
    raise errors.OpPrereqError("%s '%s' not known" % (kind, name),
                               errors.ECODE_NOENT)
  return full_name


def _ExpandNodeName(cfg, name):
  """Wrapper over L{_ExpandItemName} for nodes."""
  return _ExpandItemName(cfg.ExpandNodeName, name, "Node")


def _ExpandInstanceName(cfg, name):
  """Wrapper over L{_ExpandItemName} for instance."""
  return _ExpandItemName(cfg.ExpandInstanceName, name, "Instance")


def _BuildInstanceHookEnv(name, primary_node, secondary_nodes, os_type, status,
                          memory, vcpus, nics, disk_template, disks,
                          bep, hvp, hypervisor_name):
  """Builds instance related env variables for hooks

  This builds the hook environment from individual variables.

  @type name: string
  @param name: the name of the instance
  @type primary_node: string
  @param primary_node: the name of the instance's primary node
  @type secondary_nodes: list
  @param secondary_nodes: list of secondary nodes as strings
  @type os_type: string
  @param os_type: the name of the instance's OS
  @type status: boolean
  @param status: the should_run status of the instance
  @type memory: string
  @param memory: the memory size of the instance
  @type vcpus: string
  @param vcpus: the count of VCPUs the instance has
  @type nics: list
  @param nics: list of tuples (ip, mac, mode, link) representing
      the NICs the instance has
  @type disk_template: string
  @param disk_template: the disk template of the instance
  @type disks: list
  @param disks: the list of (size, mode) pairs
  @type bep: dict
  @param bep: the backend parameters for the instance
  @type hvp: dict
  @param hvp: the hypervisor parameters for the instance
  @type hypervisor_name: string
  @param hypervisor_name: the hypervisor for the instance
  @rtype: dict
  @return: the hook environment for this instance

  """
  if status:
    str_status = "up"
  else:
    str_status = "down"
  env = {
    "OP_TARGET": name,
    "INSTANCE_NAME": name,
    "INSTANCE_PRIMARY": primary_node,
    "INSTANCE_SECONDARIES": " ".join(secondary_nodes),
    "INSTANCE_OS_TYPE": os_type,
    "INSTANCE_STATUS": str_status,
    "INSTANCE_MEMORY": memory,
    "INSTANCE_VCPUS": vcpus,
    "INSTANCE_DISK_TEMPLATE": disk_template,
    "INSTANCE_HYPERVISOR": hypervisor_name,
  }

  if nics:
    nic_count = len(nics)
    for idx, (ip, mac, mode, link) in enumerate(nics):
      if ip is None:
        ip = ""
      env["INSTANCE_NIC%d_IP" % idx] = ip
      env["INSTANCE_NIC%d_MAC" % idx] = mac
      env["INSTANCE_NIC%d_MODE" % idx] = mode
      env["INSTANCE_NIC%d_LINK" % idx] = link
      if mode == constants.NIC_MODE_BRIDGED:
        env["INSTANCE_NIC%d_BRIDGE" % idx] = link
  else:
    nic_count = 0

  env["INSTANCE_NIC_COUNT"] = nic_count

  if disks:
    disk_count = len(disks)
    for idx, (size, mode) in enumerate(disks):
      env["INSTANCE_DISK%d_SIZE" % idx] = size
      env["INSTANCE_DISK%d_MODE" % idx] = mode
  else:
    disk_count = 0

  env["INSTANCE_DISK_COUNT"] = disk_count

  for source, kind in [(bep, "BE"), (hvp, "HV")]:
    for key, value in source.items():
      env["INSTANCE_%s_%s" % (kind, key)] = value

  return env


def _NICListToTuple(lu, nics):
  """Build a list of nic information tuples.

  This list is suitable to be passed to _BuildInstanceHookEnv or as a return
  value in LUQueryInstanceData.

  @type lu:  L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type nics: list of L{objects.NIC}
  @param nics: list of nics to convert to hooks tuples

  """
  hooks_nics = []
  cluster = lu.cfg.GetClusterInfo()
  for nic in nics:
    ip = nic.ip
    mac = nic.mac
    filled_params = cluster.SimpleFillNIC(nic.nicparams)
    mode = filled_params[constants.NIC_MODE]
    link = filled_params[constants.NIC_LINK]
    hooks_nics.append((ip, mac, mode, link))
  return hooks_nics


def _BuildInstanceHookEnvByObject(lu, instance, override=None):
  """Builds instance related env variables for hooks from an object.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type instance: L{objects.Instance}
  @param instance: the instance for which we should build the
      environment
  @type override: dict
  @param override: dictionary with key/values that will override
      our values
  @rtype: dict
  @return: the hook environment dictionary

  """
  cluster = lu.cfg.GetClusterInfo()
  bep = cluster.FillBE(instance)
  hvp = cluster.FillHV(instance)
  args = {
    'name': instance.name,
    'primary_node': instance.primary_node,
    'secondary_nodes': instance.secondary_nodes,
    'os_type': instance.os,
    'status': instance.admin_up,
    'memory': bep[constants.BE_MEMORY],
    'vcpus': bep[constants.BE_VCPUS],
    'nics': _NICListToTuple(lu, instance.nics),
    'disk_template': instance.disk_template,
    'disks': [(disk.size, disk.mode) for disk in instance.disks],
    'bep': bep,
    'hvp': hvp,
    'hypervisor_name': instance.hypervisor,
  }
  if override:
    args.update(override)
  return _BuildInstanceHookEnv(**args) # pylint: disable-msg=W0142


def _AdjustCandidatePool(lu, exceptions):
  """Adjust the candidate pool after node operations.

  """
  mod_list = lu.cfg.MaintainCandidatePool(exceptions)
  if mod_list:
    lu.LogInfo("Promoted nodes to master candidate role: %s",
               utils.CommaJoin(node.name for node in mod_list))
    for name in mod_list:
      lu.context.ReaddNode(name)
  mc_now, mc_max, _ = lu.cfg.GetMasterCandidateStats(exceptions)
  if mc_now > mc_max:
    lu.LogInfo("Note: more nodes are candidates (%d) than desired (%d)" %
               (mc_now, mc_max))


def _DecideSelfPromotion(lu, exceptions=None):
  """Decide whether I should promote myself as a master candidate.

  """
  cp_size = lu.cfg.GetClusterInfo().candidate_pool_size
  mc_now, mc_should, _ = lu.cfg.GetMasterCandidateStats(exceptions)
  # the new node will increase mc_max with one, so:
  mc_should = min(mc_should + 1, cp_size)
  return mc_now < mc_should


def _CheckNicsBridgesExist(lu, target_nics, target_node):
  """Check that the brigdes needed by a list of nics exist.

  """
  cluster = lu.cfg.GetClusterInfo()
  paramslist = [cluster.SimpleFillNIC(nic.nicparams) for nic in target_nics]
  brlist = [params[constants.NIC_LINK] for params in paramslist
            if params[constants.NIC_MODE] == constants.NIC_MODE_BRIDGED]
  if brlist:
    result = lu.rpc.call_bridges_exist(target_node, brlist)
    result.Raise("Error checking bridges on destination node '%s'" %
                 target_node, prereq=True, ecode=errors.ECODE_ENVIRON)


def _CheckInstanceBridgesExist(lu, instance, node=None):
  """Check that the brigdes needed by an instance exist.

  """
  if node is None:
    node = instance.primary_node
  _CheckNicsBridgesExist(lu, instance.nics, node)


def _CheckOSVariant(os_obj, name):
  """Check whether an OS name conforms to the os variants specification.

  @type os_obj: L{objects.OS}
  @param os_obj: OS object to check
  @type name: string
  @param name: OS name passed by the user, to check for validity

  """
  if not os_obj.supported_variants:
    return
  try:
    variant = name.split("+", 1)[1]
  except IndexError:
    raise errors.OpPrereqError("OS name must include a variant",
                               errors.ECODE_INVAL)

  if variant not in os_obj.supported_variants:
    raise errors.OpPrereqError("Unsupported OS variant", errors.ECODE_INVAL)


def _GetNodeInstancesInner(cfg, fn):
  return [i for i in cfg.GetAllInstancesInfo().values() if fn(i)]


def _GetNodeInstances(cfg, node_name):
  """Returns a list of all primary and secondary instances on a node.

  """

  return _GetNodeInstancesInner(cfg, lambda inst: node_name in inst.all_nodes)


def _GetNodePrimaryInstances(cfg, node_name):
  """Returns primary instances on a node.

  """
  return _GetNodeInstancesInner(cfg,
                                lambda inst: node_name == inst.primary_node)


def _GetNodeSecondaryInstances(cfg, node_name):
  """Returns secondary instances on a node.

  """
  return _GetNodeInstancesInner(cfg,
                                lambda inst: node_name in inst.secondary_nodes)


def _GetStorageTypeArgs(cfg, storage_type):
  """Returns the arguments for a storage type.

  """
  # Special case for file storage
  if storage_type == constants.ST_FILE:
    # storage.FileStorage wants a list of storage directories
    return [[cfg.GetFileStorageDir()]]

  return []


def _FindFaultyInstanceDisks(cfg, rpc, instance, node_name, prereq):
  faulty = []

  for dev in instance.disks:
    cfg.SetDiskID(dev, node_name)

  result = rpc.call_blockdev_getmirrorstatus(node_name, instance.disks)
  result.Raise("Failed to get disk status from node %s" % node_name,
               prereq=prereq, ecode=errors.ECODE_ENVIRON)

  for idx, bdev_status in enumerate(result.payload):
    if bdev_status and bdev_status.ldisk_status == constants.LDS_FAULTY:
      faulty.append(idx)

  return faulty


class LUPostInitCluster(LogicalUnit):
  """Logical unit for running hooks after cluster initialization.

  """
  HPATH = "cluster-init"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = []

  def BuildHooksEnv(self):
    """Build hooks env.

    """
    env = {"OP_TARGET": self.cfg.GetClusterName()}
    mn = self.cfg.GetMasterNode()
    return env, [], [mn]

  def CheckPrereq(self):
    """No prerequisites to check.

    """
    return True

  def Exec(self, feedback_fn):
    """Nothing to do.

    """
    return True


class LUDestroyCluster(LogicalUnit):
  """Logical unit for destroying the cluster.

  """
  HPATH = "cluster-destroy"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = []

  def BuildHooksEnv(self):
    """Build hooks env.

    """
    env = {"OP_TARGET": self.cfg.GetClusterName()}
    return env, [], []

  def CheckPrereq(self):
    """Check prerequisites.

    This checks whether the cluster is empty.

    Any errors are signaled by raising errors.OpPrereqError.

    """
    master = self.cfg.GetMasterNode()

    nodelist = self.cfg.GetNodeList()
    if len(nodelist) != 1 or nodelist[0] != master:
      raise errors.OpPrereqError("There are still %d node(s) in"
                                 " this cluster." % (len(nodelist) - 1),
                                 errors.ECODE_INVAL)
    instancelist = self.cfg.GetInstanceList()
    if instancelist:
      raise errors.OpPrereqError("There are still %d instance(s) in"
                                 " this cluster." % len(instancelist),
                                 errors.ECODE_INVAL)

  def Exec(self, feedback_fn):
    """Destroys the cluster.

    """
    master = self.cfg.GetMasterNode()
    modify_ssh_setup = self.cfg.GetClusterInfo().modify_ssh_setup

    # Run post hooks on master node before it's removed
    hm = self.proc.hmclass(self.rpc.call_hooks_runner, self)
    try:
      hm.RunPhase(constants.HOOKS_PHASE_POST, [master])
    except:
      # pylint: disable-msg=W0702
      self.LogWarning("Errors occurred running hooks on %s" % master)

    result = self.rpc.call_node_stop_master(master, False)
    result.Raise("Could not disable the master role")

    if modify_ssh_setup:
      priv_key, pub_key, _ = ssh.GetUserFiles(constants.GANETI_RUNAS)
      utils.CreateBackup(priv_key)
      utils.CreateBackup(pub_key)

    return master


def _VerifyCertificate(filename):
  """Verifies a certificate for LUVerifyCluster.

  @type filename: string
  @param filename: Path to PEM file

  """
  try:
    cert = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM,
                                           utils.ReadFile(filename))
  except Exception, err: # pylint: disable-msg=W0703
    return (LUVerifyCluster.ETYPE_ERROR,
            "Failed to load X509 certificate %s: %s" % (filename, err))

  (errcode, msg) = \
    utils.VerifyX509Certificate(cert, constants.SSL_CERT_EXPIRATION_WARN,
                                constants.SSL_CERT_EXPIRATION_ERROR)

  if msg:
    fnamemsg = "While verifying %s: %s" % (filename, msg)
  else:
    fnamemsg = None

  if errcode is None:
    return (None, fnamemsg)
  elif errcode == utils.CERT_WARNING:
    return (LUVerifyCluster.ETYPE_WARNING, fnamemsg)
  elif errcode == utils.CERT_ERROR:
    return (LUVerifyCluster.ETYPE_ERROR, fnamemsg)

  raise errors.ProgrammerError("Unhandled certificate error code %r" % errcode)


class LUVerifyCluster(LogicalUnit):
  """Verifies the cluster status.

  """
  HPATH = "cluster-verify"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = ["skip_checks", "verbose", "error_codes", "debug_simulate_errors"]
  REQ_BGL = False

  TCLUSTER = "cluster"
  TNODE = "node"
  TINSTANCE = "instance"

  ECLUSTERCFG = (TCLUSTER, "ECLUSTERCFG")
  ECLUSTERCERT = (TCLUSTER, "ECLUSTERCERT")
  EINSTANCEBADNODE = (TINSTANCE, "EINSTANCEBADNODE")
  EINSTANCEDOWN = (TINSTANCE, "EINSTANCEDOWN")
  EINSTANCELAYOUT = (TINSTANCE, "EINSTANCELAYOUT")
  EINSTANCEMISSINGDISK = (TINSTANCE, "EINSTANCEMISSINGDISK")
  EINSTANCEMISSINGDISK = (TINSTANCE, "EINSTANCEMISSINGDISK")
  EINSTANCEWRONGNODE = (TINSTANCE, "EINSTANCEWRONGNODE")
  ENODEDRBD = (TNODE, "ENODEDRBD")
  ENODEFILECHECK = (TNODE, "ENODEFILECHECK")
  ENODEHOOKS = (TNODE, "ENODEHOOKS")
  ENODEHV = (TNODE, "ENODEHV")
  ENODELVM = (TNODE, "ENODELVM")
  ENODEN1 = (TNODE, "ENODEN1")
  ENODENET = (TNODE, "ENODENET")
  ENODEORPHANINSTANCE = (TNODE, "ENODEORPHANINSTANCE")
  ENODEORPHANLV = (TNODE, "ENODEORPHANLV")
  ENODERPC = (TNODE, "ENODERPC")
  ENODESSH = (TNODE, "ENODESSH")
  ENODEVERSION = (TNODE, "ENODEVERSION")
  ENODESETUP = (TNODE, "ENODESETUP")
  ENODETIME = (TNODE, "ENODETIME")

  ETYPE_FIELD = "code"
  ETYPE_ERROR = "ERROR"
  ETYPE_WARNING = "WARNING"

  class NodeImage(object):
    """A class representing the logical and physical status of a node.

    @ivar volumes: a structure as returned from
        L{ganeti.backend.GetVolumeList} (runtime)
    @ivar instances: a list of running instances (runtime)
    @ivar pinst: list of configured primary instances (config)
    @ivar sinst: list of configured secondary instances (config)
    @ivar sbp: diction of {secondary-node: list of instances} of all peers
        of this node (config)
    @ivar mfree: free memory, as reported by hypervisor (runtime)
    @ivar dfree: free disk, as reported by the node (runtime)
    @ivar offline: the offline status (config)
    @type rpc_fail: boolean
    @ivar rpc_fail: whether the RPC verify call was successfull (overall,
        not whether the individual keys were correct) (runtime)
    @type lvm_fail: boolean
    @ivar lvm_fail: whether the RPC call didn't return valid LVM data
    @type hyp_fail: boolean
    @ivar hyp_fail: whether the RPC call didn't return the instance list
    @type ghost: boolean
    @ivar ghost: whether this is a known node or not (config)

    """
    def __init__(self, offline=False):
      self.volumes = {}
      self.instances = []
      self.pinst = []
      self.sinst = []
      self.sbp = {}
      self.mfree = 0
      self.dfree = 0
      self.offline = offline
      self.rpc_fail = False
      self.lvm_fail = False
      self.hyp_fail = False
      self.ghost = False

  def ExpandNames(self):
    self.needed_locks = {
      locking.LEVEL_NODE: locking.ALL_SET,
      locking.LEVEL_INSTANCE: locking.ALL_SET,
    }
    self.share_locks = dict.fromkeys(locking.LEVELS, 1)

  def _Error(self, ecode, item, msg, *args, **kwargs):
    """Format an error message.

    Based on the opcode's error_codes parameter, either format a
    parseable error code, or a simpler error string.

    This must be called only from Exec and functions called from Exec.

    """
    ltype = kwargs.get(self.ETYPE_FIELD, self.ETYPE_ERROR)
    itype, etxt = ecode
    # first complete the msg
    if args:
      msg = msg % args
    # then format the whole message
    if self.op.error_codes:
      msg = "%s:%s:%s:%s:%s" % (ltype, etxt, itype, item, msg)
    else:
      if item:
        item = " " + item
      else:
        item = ""
      msg = "%s: %s%s: %s" % (ltype, itype, item, msg)
    # and finally report it via the feedback_fn
    self._feedback_fn("  - %s" % msg)

  def _ErrorIf(self, cond, *args, **kwargs):
    """Log an error message if the passed condition is True.

    """
    cond = bool(cond) or self.op.debug_simulate_errors
    if cond:
      self._Error(*args, **kwargs)
    # do not mark the operation as failed for WARN cases only
    if kwargs.get(self.ETYPE_FIELD, self.ETYPE_ERROR) == self.ETYPE_ERROR:
      self.bad = self.bad or cond

  def _VerifyNode(self, ninfo, nresult):
    """Run multiple tests against a node.

    Test list:

      - compares ganeti version
      - checks vg existence and size > 20G
      - checks config file checksum
      - checks ssh to other nodes

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the results from the node
    @rtype: boolean
    @return: whether overall this call was successful (and we can expect
         reasonable values in the respose)

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    # main result, nresult should be a non-empty dict
    test = not nresult or not isinstance(nresult, dict)
    _ErrorIf(test, self.ENODERPC, node,
                  "unable to verify node: no data returned")
    if test:
      return False

    # compares ganeti version
    local_version = constants.PROTOCOL_VERSION
    remote_version = nresult.get("version", None)
    test = not (remote_version and
                isinstance(remote_version, (list, tuple)) and
                len(remote_version) == 2)
    _ErrorIf(test, self.ENODERPC, node,
             "connection to node returned invalid data")
    if test:
      return False

    test = local_version != remote_version[0]
    _ErrorIf(test, self.ENODEVERSION, node,
             "incompatible protocol versions: master %s,"
             " node %s", local_version, remote_version[0])
    if test:
      return False

    # node seems compatible, we can actually try to look into its results

    # full package version
    self._ErrorIf(constants.RELEASE_VERSION != remote_version[1],
                  self.ENODEVERSION, node,
                  "software version mismatch: master %s, node %s",
                  constants.RELEASE_VERSION, remote_version[1],
                  code=self.ETYPE_WARNING)

    hyp_result = nresult.get(constants.NV_HYPERVISOR, None)
    if isinstance(hyp_result, dict):
      for hv_name, hv_result in hyp_result.iteritems():
        test = hv_result is not None
        _ErrorIf(test, self.ENODEHV, node,
                 "hypervisor %s verify failure: '%s'", hv_name, hv_result)


    test = nresult.get(constants.NV_NODESETUP,
                           ["Missing NODESETUP results"])
    _ErrorIf(test, self.ENODESETUP, node, "node setup error: %s",
             "; ".join(test))

    return True

  def _VerifyNodeTime(self, ninfo, nresult,
                      nvinfo_starttime, nvinfo_endtime):
    """Check the node time.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param nvinfo_starttime: the start time of the RPC call
    @param nvinfo_endtime: the end time of the RPC call

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    ntime = nresult.get(constants.NV_TIME, None)
    try:
      ntime_merged = utils.MergeTime(ntime)
    except (ValueError, TypeError):
      _ErrorIf(True, self.ENODETIME, node, "Node returned invalid time")
      return

    if ntime_merged < (nvinfo_starttime - constants.NODE_MAX_CLOCK_SKEW):
      ntime_diff = "%.01fs" % abs(nvinfo_starttime - ntime_merged)
    elif ntime_merged > (nvinfo_endtime + constants.NODE_MAX_CLOCK_SKEW):
      ntime_diff = "%.01fs" % abs(ntime_merged - nvinfo_endtime)
    else:
      ntime_diff = None

    _ErrorIf(ntime_diff is not None, self.ENODETIME, node,
             "Node time diverges by at least %s from master node time",
             ntime_diff)

  def _VerifyNodeLVM(self, ninfo, nresult, vg_name):
    """Check the node time.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param vg_name: the configured VG name

    """
    if vg_name is None:
      return

    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    # checks vg existence and size > 20G
    vglist = nresult.get(constants.NV_VGLIST, None)
    test = not vglist
    _ErrorIf(test, self.ENODELVM, node, "unable to check volume groups")
    if not test:
      vgstatus = utils.CheckVolumeGroupSize(vglist, vg_name,
                                            constants.MIN_VG_SIZE)
      _ErrorIf(vgstatus, self.ENODELVM, node, vgstatus)

    # check pv names
    pvlist = nresult.get(constants.NV_PVLIST, None)
    test = pvlist is None
    _ErrorIf(test, self.ENODELVM, node, "Can't get PV list from node")
    if not test:
      # check that ':' is not present in PV names, since it's a
      # special character for lvcreate (denotes the range of PEs to
      # use on the PV)
      for _, pvname, owner_vg in pvlist:
        test = ":" in pvname
        _ErrorIf(test, self.ENODELVM, node, "Invalid character ':' in PV"
                 " '%s' of VG '%s'", pvname, owner_vg)

  def _VerifyNodeNetwork(self, ninfo, nresult):
    """Check the node time.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    test = constants.NV_NODELIST not in nresult
    _ErrorIf(test, self.ENODESSH, node,
             "node hasn't returned node ssh connectivity data")
    if not test:
      if nresult[constants.NV_NODELIST]:
        for a_node, a_msg in nresult[constants.NV_NODELIST].items():
          _ErrorIf(True, self.ENODESSH, node,
                   "ssh communication with node '%s': %s", a_node, a_msg)

    test = constants.NV_NODENETTEST not in nresult
    _ErrorIf(test, self.ENODENET, node,
             "node hasn't returned node tcp connectivity data")
    if not test:
      if nresult[constants.NV_NODENETTEST]:
        nlist = utils.NiceSort(nresult[constants.NV_NODENETTEST].keys())
        for anode in nlist:
          _ErrorIf(True, self.ENODENET, node,
                   "tcp communication with node '%s': %s",
                   anode, nresult[constants.NV_NODENETTEST][anode])

    test = constants.NV_MASTERIP not in nresult
    _ErrorIf(test, self.ENODENET, node,
             "node hasn't returned node master IP reachability data")
    if not test:
      if not nresult[constants.NV_MASTERIP]:
        if node == self.master_node:
          msg = "the master node cannot reach the master IP (not configured?)"
        else:
          msg = "cannot reach the master IP"
        _ErrorIf(True, self.ENODENET, node, msg)


  def _VerifyInstance(self, instance, instanceconfig, node_image):
    """Verify an instance.

    This function checks to see if the required block devices are
    available on the instance's node.

    """
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103
    node_current = instanceconfig.primary_node

    node_vol_should = {}
    instanceconfig.MapLVsByNode(node_vol_should)

    for node in node_vol_should:
      n_img = node_image[node]
      if n_img.offline or n_img.rpc_fail or n_img.lvm_fail:
        # ignore missing volumes on offline or broken nodes
        continue
      for volume in node_vol_should[node]:
        test = volume not in n_img.volumes
        _ErrorIf(test, self.EINSTANCEMISSINGDISK, instance,
                 "volume %s missing on node %s", volume, node)

    if instanceconfig.admin_up:
      pri_img = node_image[node_current]
      test = instance not in pri_img.instances and not pri_img.offline
      _ErrorIf(test, self.EINSTANCEDOWN, instance,
               "instance not running on its primary node %s",
               node_current)

    for node, n_img in node_image.items():
      if (not node == node_current):
        test = instance in n_img.instances
        _ErrorIf(test, self.EINSTANCEWRONGNODE, instance,
                 "instance should not run on node %s", node)

  def _VerifyOrphanVolumes(self, node_vol_should, node_image):
    """Verify if there are any unknown volumes in the cluster.

    The .os, .swap and backup volumes are ignored. All other volumes are
    reported as unknown.

    """
    for node, n_img in node_image.items():
      if n_img.offline or n_img.rpc_fail or n_img.lvm_fail:
        # skip non-healthy nodes
        continue
      for volume in n_img.volumes:
        test = (node not in node_vol_should or
                volume not in node_vol_should[node])
        self._ErrorIf(test, self.ENODEORPHANLV, node,
                      "volume %s is unknown", volume)

  def _VerifyOrphanInstances(self, instancelist, node_image):
    """Verify the list of running instances.

    This checks what instances are running but unknown to the cluster.

    """
    for node, n_img in node_image.items():
      for o_inst in n_img.instances:
        test = o_inst not in instancelist
        self._ErrorIf(test, self.ENODEORPHANINSTANCE, node,
                      "instance %s on node %s should not exist", o_inst, node)

  def _VerifyNPlusOneMemory(self, node_image, instance_cfg):
    """Verify N+1 Memory Resilience.

    Check that if one single node dies we can still start all the
    instances it was primary for.

    """
    for node, n_img in node_image.items():
      # This code checks that every node which is now listed as
      # secondary has enough memory to host all instances it is
      # supposed to should a single other node in the cluster fail.
      # FIXME: not ready for failover to an arbitrary node
      # FIXME: does not support file-backed instances
      # WARNING: we currently take into account down instances as well
      # as up ones, considering that even if they're down someone
      # might want to start them even in the event of a node failure.
      for prinode, instances in n_img.sbp.items():
        needed_mem = 0
        for instance in instances:
          bep = self.cfg.GetClusterInfo().FillBE(instance_cfg[instance])
          if bep[constants.BE_AUTO_BALANCE]:
            needed_mem += bep[constants.BE_MEMORY]
        test = n_img.mfree < needed_mem
        self._ErrorIf(test, self.ENODEN1, node,
                      "not enough memory on to accommodate"
                      " failovers should peer node %s fail", prinode)

  def _VerifyNodeFiles(self, ninfo, nresult, file_list, local_cksum,
                       master_files):
    """Verifies and computes the node required file checksums.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param file_list: required list of files
    @param local_cksum: dictionary of local files and their checksums
    @param master_files: list of files that only masters should have

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    remote_cksum = nresult.get(constants.NV_FILELIST, None)
    test = not isinstance(remote_cksum, dict)
    _ErrorIf(test, self.ENODEFILECHECK, node,
             "node hasn't returned file checksum data")
    if test:
      return

    for file_name in file_list:
      node_is_mc = ninfo.master_candidate
      must_have = (file_name not in master_files) or node_is_mc
      # missing
      test1 = file_name not in remote_cksum
      # invalid checksum
      test2 = not test1 and remote_cksum[file_name] != local_cksum[file_name]
      # existing and good
      test3 = not test1 and remote_cksum[file_name] == local_cksum[file_name]
      _ErrorIf(test1 and must_have, self.ENODEFILECHECK, node,
               "file '%s' missing", file_name)
      _ErrorIf(test2 and must_have, self.ENODEFILECHECK, node,
               "file '%s' has wrong checksum", file_name)
      # not candidate and this is not a must-have file
      _ErrorIf(test2 and not must_have, self.ENODEFILECHECK, node,
               "file '%s' should not exist on non master"
               " candidates (and the file is outdated)", file_name)
      # all good, except non-master/non-must have combination
      _ErrorIf(test3 and not must_have, self.ENODEFILECHECK, node,
               "file '%s' should not exist"
               " on non master candidates", file_name)

  def _VerifyNodeDrbd(self, ninfo, nresult, instanceinfo, drbd_map):
    """Verifies and the node DRBD status.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param instanceinfo: the dict of instances
    @param drbd_map: the DRBD map as returned by
        L{ganeti.config.ConfigWriter.ComputeDRBDMap}

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    # compute the DRBD minors
    node_drbd = {}
    for minor, instance in drbd_map[node].items():
      test = instance not in instanceinfo
      _ErrorIf(test, self.ECLUSTERCFG, None,
               "ghost instance '%s' in temporary DRBD map", instance)
        # ghost instance should not be running, but otherwise we
        # don't give double warnings (both ghost instance and
        # unallocated minor in use)
      if test:
        node_drbd[minor] = (instance, False)
      else:
        instance = instanceinfo[instance]
        node_drbd[minor] = (instance.name, instance.admin_up)

    # and now check them
    used_minors = nresult.get(constants.NV_DRBDLIST, [])
    test = not isinstance(used_minors, (tuple, list))
    _ErrorIf(test, self.ENODEDRBD, node,
             "cannot parse drbd status file: %s", str(used_minors))
    if test:
      # we cannot check drbd status
      return

    for minor, (iname, must_exist) in node_drbd.items():
      test = minor not in used_minors and must_exist
      _ErrorIf(test, self.ENODEDRBD, node,
               "drbd minor %d of instance %s is not active", minor, iname)
    for minor in used_minors:
      test = minor not in node_drbd
      _ErrorIf(test, self.ENODEDRBD, node,
               "unallocated drbd minor %d is in use", minor)

  def _UpdateNodeVolumes(self, ninfo, nresult, nimg, vg_name):
    """Verifies and updates the node volume data.

    This function will update a L{NodeImage}'s internal structures
    with data from the remote call.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param nimg: the node image object
    @param vg_name: the configured VG name

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    nimg.lvm_fail = True
    lvdata = nresult.get(constants.NV_LVLIST, "Missing LV data")
    if vg_name is None:
      pass
    elif isinstance(lvdata, basestring):
      _ErrorIf(True, self.ENODELVM, node, "LVM problem on node: %s",
               utils.SafeEncode(lvdata))
    elif not isinstance(lvdata, dict):
      _ErrorIf(True, self.ENODELVM, node, "rpc call to node failed (lvlist)")
    else:
      nimg.volumes = lvdata
      nimg.lvm_fail = False

  def _UpdateNodeInstances(self, ninfo, nresult, nimg):
    """Verifies and updates the node instance list.

    If the listing was successful, then updates this node's instance
    list. Otherwise, it marks the RPC call as failed for the instance
    list key.

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param nimg: the node image object

    """
    idata = nresult.get(constants.NV_INSTANCELIST, None)
    test = not isinstance(idata, list)
    self._ErrorIf(test, self.ENODEHV, ninfo.name, "rpc call to node failed"
                  " (instancelist): %s", utils.SafeEncode(str(idata)))
    if test:
      nimg.hyp_fail = True
    else:
      nimg.instances = idata

  def _UpdateNodeInfo(self, ninfo, nresult, nimg, vg_name):
    """Verifies and computes a node information map

    @type ninfo: L{objects.Node}
    @param ninfo: the node to check
    @param nresult: the remote results for the node
    @param nimg: the node image object
    @param vg_name: the configured VG name

    """
    node = ninfo.name
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103

    # try to read free memory (from the hypervisor)
    hv_info = nresult.get(constants.NV_HVINFO, None)
    test = not isinstance(hv_info, dict) or "memory_free" not in hv_info
    _ErrorIf(test, self.ENODEHV, node, "rpc call to node failed (hvinfo)")
    if not test:
      try:
        nimg.mfree = int(hv_info["memory_free"])
      except (ValueError, TypeError):
        _ErrorIf(True, self.ENODERPC, node,
                 "node returned invalid nodeinfo, check hypervisor")

    # FIXME: devise a free space model for file based instances as well
    if vg_name is not None:
      test = (constants.NV_VGLIST not in nresult or
              vg_name not in nresult[constants.NV_VGLIST])
      _ErrorIf(test, self.ENODELVM, node,
               "node didn't return data for the volume group '%s'"
               " - it is either missing or broken", vg_name)
      if not test:
        try:
          nimg.dfree = int(nresult[constants.NV_VGLIST][vg_name])
        except (ValueError, TypeError):
          _ErrorIf(True, self.ENODERPC, node,
                   "node returned invalid LVM info, check LVM status")

  def CheckPrereq(self):
    """Check prerequisites.

    Transform the list of checks we're going to skip into a set and check that
    all its members are valid.

    """
    self.skip_set = frozenset(self.op.skip_checks)
    if not constants.VERIFY_OPTIONAL_CHECKS.issuperset(self.skip_set):
      raise errors.OpPrereqError("Invalid checks to be skipped specified",
                                 errors.ECODE_INVAL)

  def BuildHooksEnv(self):
    """Build hooks env.

    Cluster-Verify hooks just ran in the post phase and their failure makes
    the output be logged in the verify output and the verification to fail.

    """
    all_nodes = self.cfg.GetNodeList()
    env = {
      "CLUSTER_TAGS": " ".join(self.cfg.GetClusterInfo().GetTags())
      }
    for node in self.cfg.GetAllNodesInfo().values():
      env["NODE_TAGS_%s" % node.name] = " ".join(node.GetTags())

    return env, [], all_nodes

  def Exec(self, feedback_fn):
    """Verify integrity of cluster, performing various test on nodes.

    """
    self.bad = False
    _ErrorIf = self._ErrorIf # pylint: disable-msg=C0103
    verbose = self.op.verbose
    self._feedback_fn = feedback_fn
    feedback_fn("* Verifying global settings")
    for msg in self.cfg.VerifyConfig():
      _ErrorIf(True, self.ECLUSTERCFG, None, msg)

    # Check the cluster certificates
    for cert_filename in constants.ALL_CERT_FILES:
      (errcode, msg) = _VerifyCertificate(cert_filename)
      _ErrorIf(errcode, self.ECLUSTERCERT, None, msg, code=errcode)

    vg_name = self.cfg.GetVGName()
    hypervisors = self.cfg.GetClusterInfo().enabled_hypervisors
    cluster = self.cfg.GetClusterInfo()
    nodelist = utils.NiceSort(self.cfg.GetNodeList())
    nodeinfo = [self.cfg.GetNodeInfo(nname) for nname in nodelist]
    instancelist = utils.NiceSort(self.cfg.GetInstanceList())
    instanceinfo = dict((iname, self.cfg.GetInstanceInfo(iname))
                        for iname in instancelist)
    i_non_redundant = [] # Non redundant instances
    i_non_a_balanced = [] # Non auto-balanced instances
    n_offline = 0 # Count of offline nodes
    n_drained = 0 # Count of nodes being drained
    node_vol_should = {}

    # FIXME: verify OS list
    # do local checksums
    master_files = [constants.CLUSTER_CONF_FILE]
    master_node = self.master_node = self.cfg.GetMasterNode()
    master_ip = self.cfg.GetMasterIP()

    file_names = ssconf.SimpleStore().GetFileList()
    file_names.extend(constants.ALL_CERT_FILES)
    file_names.extend(master_files)
    if cluster.modify_etc_hosts:
      file_names.append(constants.ETC_HOSTS)

    local_checksums = utils.FingerprintFiles(file_names)

    feedback_fn("* Gathering data (%d nodes)" % len(nodelist))
    node_verify_param = {
      constants.NV_FILELIST: file_names,
      constants.NV_NODELIST: [node.name for node in nodeinfo
                              if not node.offline],
      constants.NV_HYPERVISOR: hypervisors,
      constants.NV_NODENETTEST: [(node.name, node.primary_ip,
                                  node.secondary_ip) for node in nodeinfo
                                 if not node.offline],
      constants.NV_INSTANCELIST: hypervisors,
      constants.NV_VERSION: None,
      constants.NV_HVINFO: self.cfg.GetHypervisorType(),
      constants.NV_NODESETUP: None,
      constants.NV_TIME: None,
      constants.NV_MASTERIP: (master_node, master_ip),
      }

    if vg_name is not None:
      node_verify_param[constants.NV_VGLIST] = None
      node_verify_param[constants.NV_LVLIST] = vg_name
      node_verify_param[constants.NV_PVLIST] = [vg_name]
      node_verify_param[constants.NV_DRBDLIST] = None

    # Build our expected cluster state
    node_image = dict((node.name, self.NodeImage(offline=node.offline))
                      for node in nodeinfo)

    for instance in instancelist:
      inst_config = instanceinfo[instance]

      for nname in inst_config.all_nodes:
        if nname not in node_image:
          # ghost node
          gnode = self.NodeImage()
          gnode.ghost = True
          node_image[nname] = gnode

      inst_config.MapLVsByNode(node_vol_should)

      pnode = inst_config.primary_node
      node_image[pnode].pinst.append(instance)

      for snode in inst_config.secondary_nodes:
        nimg = node_image[snode]
        nimg.sinst.append(instance)
        if pnode not in nimg.sbp:
          nimg.sbp[pnode] = []
        nimg.sbp[pnode].append(instance)

    # At this point, we have the in-memory data structures complete,
    # except for the runtime information, which we'll gather next

    # Due to the way our RPC system works, exact response times cannot be
    # guaranteed (e.g. a broken node could run into a timeout). By keeping the
    # time before and after executing the request, we can at least have a time
    # window.
    nvinfo_starttime = time.time()
    all_nvinfo = self.rpc.call_node_verify(nodelist, node_verify_param,
                                           self.cfg.GetClusterName())
    nvinfo_endtime = time.time()

    all_drbd_map = self.cfg.ComputeDRBDMap()

    feedback_fn("* Verifying node status")
    for node_i in nodeinfo:
      node = node_i.name
      nimg = node_image[node]

      if node_i.offline:
        if verbose:
          feedback_fn("* Skipping offline node %s" % (node,))
        n_offline += 1
        continue

      if node == master_node:
        ntype = "master"
      elif node_i.master_candidate:
        ntype = "master candidate"
      elif node_i.drained:
        ntype = "drained"
        n_drained += 1
      else:
        ntype = "regular"
      if verbose:
        feedback_fn("* Verifying node %s (%s)" % (node, ntype))

      msg = all_nvinfo[node].fail_msg
      _ErrorIf(msg, self.ENODERPC, node, "while contacting node: %s", msg)
      if msg:
        nimg.rpc_fail = True
        continue

      nresult = all_nvinfo[node].payload

      nimg.call_ok = self._VerifyNode(node_i, nresult)
      self._VerifyNodeNetwork(node_i, nresult)
      self._VerifyNodeLVM(node_i, nresult, vg_name)
      self._VerifyNodeFiles(node_i, nresult, file_names, local_checksums,
                            master_files)
      self._VerifyNodeDrbd(node_i, nresult, instanceinfo, all_drbd_map)
      self._VerifyNodeTime(node_i, nresult, nvinfo_starttime, nvinfo_endtime)

      self._UpdateNodeVolumes(node_i, nresult, nimg, vg_name)
      self._UpdateNodeInstances(node_i, nresult, nimg)
      self._UpdateNodeInfo(node_i, nresult, nimg, vg_name)

    feedback_fn("* Verifying instance status")
    for instance in instancelist:
      if verbose:
        feedback_fn("* Verifying instance %s" % instance)
      inst_config = instanceinfo[instance]
      self._VerifyInstance(instance, inst_config, node_image)
      inst_nodes_offline = []

      pnode = inst_config.primary_node
      pnode_img = node_image[pnode]
      _ErrorIf(pnode_img.rpc_fail and not pnode_img.offline,
               self.ENODERPC, pnode, "instance %s, connection to"
               " primary node failed", instance)

      if pnode_img.offline:
        inst_nodes_offline.append(pnode)

      # If the instance is non-redundant we cannot survive losing its primary
      # node, so we are not N+1 compliant. On the other hand we have no disk
      # templates with more than one secondary so that situation is not well
      # supported either.
      # FIXME: does not support file-backed instances
      if not inst_config.secondary_nodes:
        i_non_redundant.append(instance)
      _ErrorIf(len(inst_config.secondary_nodes) > 1, self.EINSTANCELAYOUT,
               instance, "instance has multiple secondary nodes: %s",
               utils.CommaJoin(inst_config.secondary_nodes),
               code=self.ETYPE_WARNING)

      if not cluster.FillBE(inst_config)[constants.BE_AUTO_BALANCE]:
        i_non_a_balanced.append(instance)

      for snode in inst_config.secondary_nodes:
        s_img = node_image[snode]
        _ErrorIf(s_img.rpc_fail and not s_img.offline, self.ENODERPC, snode,
                 "instance %s, connection to secondary node failed", instance)

        if s_img.offline:
          inst_nodes_offline.append(snode)

      # warn that the instance lives on offline nodes
      _ErrorIf(inst_nodes_offline, self.EINSTANCEBADNODE, instance,
               "instance lives on offline node(s) %s",
               utils.CommaJoin(inst_nodes_offline))
      # ... or ghost nodes
      for node in inst_config.all_nodes:
        _ErrorIf(node_image[node].ghost, self.EINSTANCEBADNODE, instance,
                 "instance lives on ghost node %s", node)

    feedback_fn("* Verifying orphan volumes")
    self._VerifyOrphanVolumes(node_vol_should, node_image)

    feedback_fn("* Verifying orphan instances")
    self._VerifyOrphanInstances(instancelist, node_image)

    if constants.VERIFY_NPLUSONE_MEM not in self.skip_set:
      feedback_fn("* Verifying N+1 Memory redundancy")
      self._VerifyNPlusOneMemory(node_image, instanceinfo)

    feedback_fn("* Other Notes")
    if i_non_redundant:
      feedback_fn("  - NOTICE: %d non-redundant instance(s) found."
                  % len(i_non_redundant))

    if i_non_a_balanced:
      feedback_fn("  - NOTICE: %d non-auto-balanced instance(s) found."
                  % len(i_non_a_balanced))

    if n_offline:
      feedback_fn("  - NOTICE: %d offline node(s) found." % n_offline)

    if n_drained:
      feedback_fn("  - NOTICE: %d drained node(s) found." % n_drained)

    return not self.bad

  def HooksCallBack(self, phase, hooks_results, feedback_fn, lu_result):
    """Analyze the post-hooks' result

    This method analyses the hook result, handles it, and sends some
    nicely-formatted feedback back to the user.

    @param phase: one of L{constants.HOOKS_PHASE_POST} or
        L{constants.HOOKS_PHASE_PRE}; it denotes the hooks phase
    @param hooks_results: the results of the multi-node hooks rpc call
    @param feedback_fn: function used send feedback back to the caller
    @param lu_result: previous Exec result
    @return: the new Exec result, based on the previous result
        and hook results

    """
    # We only really run POST phase hooks, and are only interested in
    # their results
    if phase == constants.HOOKS_PHASE_POST:
      # Used to change hooks' output to proper indentation
      indent_re = re.compile('^', re.M)
      feedback_fn("* Hooks Results")
      assert hooks_results, "invalid result from hooks"

      for node_name in hooks_results:
        res = hooks_results[node_name]
        msg = res.fail_msg
        test = msg and not res.offline
        self._ErrorIf(test, self.ENODEHOOKS, node_name,
                      "Communication failure in hooks execution: %s", msg)
        if res.offline or msg:
          # No need to investigate payload if node is offline or gave an error.
          # override manually lu_result here as _ErrorIf only
          # overrides self.bad
          lu_result = 1
          continue
        for script, hkr, output in res.payload:
          test = hkr == constants.HKR_FAIL
          self._ErrorIf(test, self.ENODEHOOKS, node_name,
                        "Script %s failed, output:", script)
          if test:
            output = indent_re.sub('      ', output)
            feedback_fn("%s" % output)
            lu_result = 0

      return lu_result


class LUVerifyDisks(NoHooksLU):
  """Verifies the cluster disks status.

  """
  _OP_REQP = []
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {
      locking.LEVEL_NODE: locking.ALL_SET,
      locking.LEVEL_INSTANCE: locking.ALL_SET,
    }
    self.share_locks = dict.fromkeys(locking.LEVELS, 1)

  def CheckPrereq(self):
    """Check prerequisites.

    This has no prerequisites.

    """
    pass

  def Exec(self, feedback_fn):
    """Verify integrity of cluster disks.

    @rtype: tuple of three items
    @return: a tuple of (dict of node-to-node_error, list of instances
        which need activate-disks, dict of instance: (node, volume) for
        missing volumes

    """
    result = res_nodes, res_instances, res_missing = {}, [], {}

    vg_name = self.cfg.GetVGName()
    nodes = utils.NiceSort(self.cfg.GetNodeList())
    instances = [self.cfg.GetInstanceInfo(name)
                 for name in self.cfg.GetInstanceList()]

    nv_dict = {}
    for inst in instances:
      inst_lvs = {}
      if (not inst.admin_up or
          inst.disk_template not in constants.DTS_NET_MIRROR):
        continue
      inst.MapLVsByNode(inst_lvs)
      # transform { iname: {node: [vol,],},} to {(node, vol): iname}
      for node, vol_list in inst_lvs.iteritems():
        for vol in vol_list:
          nv_dict[(node, vol)] = inst

    if not nv_dict:
      return result

    node_lvs = self.rpc.call_lv_list(nodes, vg_name)

    for node in nodes:
      # node_volume
      node_res = node_lvs[node]
      if node_res.offline:
        continue
      msg = node_res.fail_msg
      if msg:
        logging.warning("Error enumerating LVs on node %s: %s", node, msg)
        res_nodes[node] = msg
        continue

      lvs = node_res.payload
      for lv_name, (_, _, lv_online) in lvs.items():
        inst = nv_dict.pop((node, lv_name), None)
        if (not lv_online and inst is not None
            and inst.name not in res_instances):
          res_instances.append(inst.name)

    # any leftover items in nv_dict are missing LVs, let's arrange the
    # data better
    for key, inst in nv_dict.iteritems():
      if inst.name not in res_missing:
        res_missing[inst.name] = []
      res_missing[inst.name].append(key)

    return result


class LURepairDiskSizes(NoHooksLU):
  """Verifies the cluster disks sizes.

  """
  _OP_REQP = ["instances"]
  REQ_BGL = False

  def ExpandNames(self):
    if not isinstance(self.op.instances, list):
      raise errors.OpPrereqError("Invalid argument type 'instances'",
                                 errors.ECODE_INVAL)

    if self.op.instances:
      self.wanted_names = []
      for name in self.op.instances:
        full_name = _ExpandInstanceName(self.cfg, name)
        self.wanted_names.append(full_name)
      self.needed_locks = {
        locking.LEVEL_NODE: [],
        locking.LEVEL_INSTANCE: self.wanted_names,
        }
      self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE
    else:
      self.wanted_names = None
      self.needed_locks = {
        locking.LEVEL_NODE: locking.ALL_SET,
        locking.LEVEL_INSTANCE: locking.ALL_SET,
        }
    self.share_locks = dict(((i, 1) for i in locking.LEVELS))

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE and self.wanted_names is not None:
      self._LockInstancesNodes(primary_only=True)

  def CheckPrereq(self):
    """Check prerequisites.

    This only checks the optional instance list against the existing names.

    """
    if self.wanted_names is None:
      self.wanted_names = self.acquired_locks[locking.LEVEL_INSTANCE]

    self.wanted_instances = [self.cfg.GetInstanceInfo(name) for name
                             in self.wanted_names]

  def _EnsureChildSizes(self, disk):
    """Ensure children of the disk have the needed disk size.

    This is valid mainly for DRBD8 and fixes an issue where the
    children have smaller disk size.

    @param disk: an L{ganeti.objects.Disk} object

    """
    if disk.dev_type == constants.LD_DRBD8:
      assert disk.children, "Empty children for DRBD8?"
      fchild = disk.children[0]
      mismatch = fchild.size < disk.size
      if mismatch:
        self.LogInfo("Child disk has size %d, parent %d, fixing",
                     fchild.size, disk.size)
        fchild.size = disk.size

      # and we recurse on this child only, not on the metadev
      return self._EnsureChildSizes(fchild) or mismatch
    else:
      return False

  def Exec(self, feedback_fn):
    """Verify the size of cluster disks.

    """
    # TODO: check child disks too
    # TODO: check differences in size between primary/secondary nodes
    per_node_disks = {}
    for instance in self.wanted_instances:
      pnode = instance.primary_node
      if pnode not in per_node_disks:
        per_node_disks[pnode] = []
      for idx, disk in enumerate(instance.disks):
        per_node_disks[pnode].append((instance, idx, disk))

    changed = []
    for node, dskl in per_node_disks.items():
      newl = [v[2].Copy() for v in dskl]
      for dsk in newl:
        self.cfg.SetDiskID(dsk, node)
      result = self.rpc.call_blockdev_getsizes(node, newl)
      if result.fail_msg:
        self.LogWarning("Failure in blockdev_getsizes call to node"
                        " %s, ignoring", node)
        continue
      if len(result.data) != len(dskl):
        self.LogWarning("Invalid result from node %s, ignoring node results",
                        node)
        continue
      for ((instance, idx, disk), size) in zip(dskl, result.data):
        if size is None:
          self.LogWarning("Disk %d of instance %s did not return size"
                          " information, ignoring", idx, instance.name)
          continue
        if not isinstance(size, (int, long)):
          self.LogWarning("Disk %d of instance %s did not return valid"
                          " size information, ignoring", idx, instance.name)
          continue
        size = size >> 20
        if size != disk.size:
          self.LogInfo("Disk %d of instance %s has mismatched size,"
                       " correcting: recorded %d, actual %d", idx,
                       instance.name, disk.size, size)
          disk.size = size
          self.cfg.Update(instance, feedback_fn)
          changed.append((instance.name, idx, size))
        if self._EnsureChildSizes(disk):
          self.cfg.Update(instance, feedback_fn)
          changed.append((instance.name, idx, disk.size))
    return changed


class LURenameCluster(LogicalUnit):
  """Rename the cluster.

  """
  HPATH = "cluster-rename"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = ["name"]

  def BuildHooksEnv(self):
    """Build hooks env.

    """
    env = {
      "OP_TARGET": self.cfg.GetClusterName(),
      "NEW_NAME": self.op.name,
      }
    mn = self.cfg.GetMasterNode()
    all_nodes = self.cfg.GetNodeList()
    return env, [mn], all_nodes

  def CheckPrereq(self):
    """Verify that the passed name is a valid one.

    """
    hostname = utils.GetHostInfo(self.op.name)

    new_name = hostname.name
    self.ip = new_ip = hostname.ip
    old_name = self.cfg.GetClusterName()
    old_ip = self.cfg.GetMasterIP()
    if new_name == old_name and new_ip == old_ip:
      raise errors.OpPrereqError("Neither the name nor the IP address of the"
                                 " cluster has changed",
                                 errors.ECODE_INVAL)
    if new_ip != old_ip:
      if utils.TcpPing(new_ip, constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("The given cluster IP address (%s) is"
                                   " reachable on the network. Aborting." %
                                   new_ip, errors.ECODE_NOTUNIQUE)

    self.op.name = new_name

  def Exec(self, feedback_fn):
    """Rename the cluster.

    """
    clustername = self.op.name
    ip = self.ip

    # shutdown the master IP
    master = self.cfg.GetMasterNode()
    result = self.rpc.call_node_stop_master(master, False)
    result.Raise("Could not disable the master role")

    try:
      cluster = self.cfg.GetClusterInfo()
      cluster.cluster_name = clustername
      cluster.master_ip = ip
      self.cfg.Update(cluster, feedback_fn)

      # update the known hosts file
      ssh.WriteKnownHostsFile(self.cfg, constants.SSH_KNOWN_HOSTS_FILE)
      node_list = self.cfg.GetNodeList()
      try:
        node_list.remove(master)
      except ValueError:
        pass
      result = self.rpc.call_upload_file(node_list,
                                         constants.SSH_KNOWN_HOSTS_FILE)
      for to_node, to_result in result.iteritems():
        msg = to_result.fail_msg
        if msg:
          msg = ("Copy of file %s to node %s failed: %s" %
                 (constants.SSH_KNOWN_HOSTS_FILE, to_node, msg))
          self.proc.LogWarning(msg)

    finally:
      result = self.rpc.call_node_start_master(master, False, False)
      msg = result.fail_msg
      if msg:
        self.LogWarning("Could not re-enable the master role on"
                        " the master, please restart manually: %s", msg)


def _RecursiveCheckIfLVMBased(disk):
  """Check if the given disk or its children are lvm-based.

  @type disk: L{objects.Disk}
  @param disk: the disk to check
  @rtype: boolean
  @return: boolean indicating whether a LD_LV dev_type was found or not

  """
  if disk.children:
    for chdisk in disk.children:
      if _RecursiveCheckIfLVMBased(chdisk):
        return True
  return disk.dev_type == constants.LD_LV


class LUSetClusterParams(LogicalUnit):
  """Change the parameters of the cluster.

  """
  HPATH = "cluster-modify"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = []
  REQ_BGL = False

  def CheckArguments(self):
    """Check parameters

    """
    for attr in ["candidate_pool_size",
                 "uid_pool", "add_uids", "remove_uids"]:
      if not hasattr(self.op, attr):
        setattr(self.op, attr, None)

    if self.op.candidate_pool_size is not None:
      try:
        self.op.candidate_pool_size = int(self.op.candidate_pool_size)
      except (ValueError, TypeError), err:
        raise errors.OpPrereqError("Invalid candidate_pool_size value: %s" %
                                   str(err), errors.ECODE_INVAL)
      if self.op.candidate_pool_size < 1:
        raise errors.OpPrereqError("At least one master candidate needed",
                                   errors.ECODE_INVAL)

    _CheckBooleanOpField(self.op, "maintain_node_health")

    if self.op.uid_pool:
      uidpool.CheckUidPool(self.op.uid_pool)

    if self.op.add_uids:
      uidpool.CheckUidPool(self.op.add_uids)

    if self.op.remove_uids:
      uidpool.CheckUidPool(self.op.remove_uids)

  def ExpandNames(self):
    # FIXME: in the future maybe other cluster params won't require checking on
    # all nodes to be modified.
    self.needed_locks = {
      locking.LEVEL_NODE: locking.ALL_SET,
    }
    self.share_locks[locking.LEVEL_NODE] = 1

  def BuildHooksEnv(self):
    """Build hooks env.

    """
    env = {
      "OP_TARGET": self.cfg.GetClusterName(),
      "NEW_VG_NAME": self.op.vg_name,
      }
    mn = self.cfg.GetMasterNode()
    return env, [mn], [mn]

  def CheckPrereq(self):
    """Check prerequisites.

    This checks whether the given params don't conflict and
    if the given volume group is valid.

    """
    if self.op.vg_name is not None and not self.op.vg_name:
      instances = self.cfg.GetAllInstancesInfo().values()
      for inst in instances:
        for disk in inst.disks:
          if _RecursiveCheckIfLVMBased(disk):
            raise errors.OpPrereqError("Cannot disable lvm storage while"
                                       " lvm-based instances exist",
                                       errors.ECODE_INVAL)

    node_list = self.acquired_locks[locking.LEVEL_NODE]

    # if vg_name not None, checks given volume group on all nodes
    if self.op.vg_name:
      vglist = self.rpc.call_vg_list(node_list)
      for node in node_list:
        msg = vglist[node].fail_msg
        if msg:
          # ignoring down node
          self.LogWarning("Error while gathering data on node %s"
                          " (ignoring node): %s", node, msg)
          continue
        vgstatus = utils.CheckVolumeGroupSize(vglist[node].payload,
                                              self.op.vg_name,
                                              constants.MIN_VG_SIZE)
        if vgstatus:
          raise errors.OpPrereqError("Error on node '%s': %s" %
                                     (node, vgstatus), errors.ECODE_ENVIRON)

    self.cluster = cluster = self.cfg.GetClusterInfo()
    # validate params changes
    if self.op.beparams:
      utils.ForceDictType(self.op.beparams, constants.BES_PARAMETER_TYPES)
      self.new_beparams = cluster.SimpleFillBE(self.op.beparams)

    if self.op.nicparams:
      utils.ForceDictType(self.op.nicparams, constants.NICS_PARAMETER_TYPES)
      self.new_nicparams = cluster.SimpleFillNIC(self.op.nicparams)
      objects.NIC.CheckParameterSyntax(self.new_nicparams)
      nic_errors = []

      # check all instances for consistency
      for instance in self.cfg.GetAllInstancesInfo().values():
        for nic_idx, nic in enumerate(instance.nics):
          params_copy = copy.deepcopy(nic.nicparams)
          params_filled = objects.FillDict(self.new_nicparams, params_copy)

          # check parameter syntax
          try:
            objects.NIC.CheckParameterSyntax(params_filled)
          except errors.ConfigurationError, err:
            nic_errors.append("Instance %s, nic/%d: %s" %
                              (instance.name, nic_idx, err))

          # if we're moving instances to routed, check that they have an ip
          target_mode = params_filled[constants.NIC_MODE]
          if target_mode == constants.NIC_MODE_ROUTED and not nic.ip:
            nic_errors.append("Instance %s, nic/%d: routed nick with no ip" %
                              (instance.name, nic_idx))
      if nic_errors:
        raise errors.OpPrereqError("Cannot apply the change, errors:\n%s" %
                                   "\n".join(nic_errors))

    # hypervisor list/parameters
    self.new_hvparams = new_hvp = objects.FillDict(cluster.hvparams, {})
    if self.op.hvparams:
      if not isinstance(self.op.hvparams, dict):
        raise errors.OpPrereqError("Invalid 'hvparams' parameter on input",
                                   errors.ECODE_INVAL)
      for hv_name, hv_dict in self.op.hvparams.items():
        if hv_name not in self.new_hvparams:
          self.new_hvparams[hv_name] = hv_dict
        else:
          self.new_hvparams[hv_name].update(hv_dict)

    # os hypervisor parameters
    self.new_os_hvp = objects.FillDict(cluster.os_hvp, {})
    if self.op.os_hvp:
      if not isinstance(self.op.os_hvp, dict):
        raise errors.OpPrereqError("Invalid 'os_hvp' parameter on input",
                                   errors.ECODE_INVAL)
      for os_name, hvs in self.op.os_hvp.items():
        if not isinstance(hvs, dict):
          raise errors.OpPrereqError(("Invalid 'os_hvp' parameter on"
                                      " input"), errors.ECODE_INVAL)
        if os_name not in self.new_os_hvp:
          self.new_os_hvp[os_name] = hvs
        else:
          for hv_name, hv_dict in hvs.items():
            if hv_name not in self.new_os_hvp[os_name]:
              self.new_os_hvp[os_name][hv_name] = hv_dict
            else:
              self.new_os_hvp[os_name][hv_name].update(hv_dict)

    # changes to the hypervisor list
    if self.op.enabled_hypervisors is not None:
      self.hv_list = self.op.enabled_hypervisors
      if not self.hv_list:
        raise errors.OpPrereqError("Enabled hypervisors list must contain at"
                                   " least one member",
                                   errors.ECODE_INVAL)
      invalid_hvs = set(self.hv_list) - constants.HYPER_TYPES
      if invalid_hvs:
        raise errors.OpPrereqError("Enabled hypervisors contains invalid"
                                   " entries: %s" %
                                   utils.CommaJoin(invalid_hvs),
                                   errors.ECODE_INVAL)
      for hv in self.hv_list:
        # if the hypervisor doesn't already exist in the cluster
        # hvparams, we initialize it to empty, and then (in both
        # cases) we make sure to fill the defaults, as we might not
        # have a complete defaults list if the hypervisor wasn't
        # enabled before
        if hv not in new_hvp:
          new_hvp[hv] = {}
        new_hvp[hv] = objects.FillDict(constants.HVC_DEFAULTS[hv], new_hvp[hv])
        utils.ForceDictType(new_hvp[hv], constants.HVS_PARAMETER_TYPES)
    else:
      self.hv_list = cluster.enabled_hypervisors

    if self.op.hvparams or self.op.enabled_hypervisors is not None:
      # either the enabled list has changed, or the parameters have, validate
      for hv_name, hv_params in self.new_hvparams.items():
        if ((self.op.hvparams and hv_name in self.op.hvparams) or
            (self.op.enabled_hypervisors and
             hv_name in self.op.enabled_hypervisors)):
          # either this is a new hypervisor, or its parameters have changed
          hv_class = hypervisor.GetHypervisor(hv_name)
          utils.ForceDictType(hv_params, constants.HVS_PARAMETER_TYPES)
          hv_class.CheckParameterSyntax(hv_params)
          _CheckHVParams(self, node_list, hv_name, hv_params)

    if self.op.os_hvp:
      # no need to check any newly-enabled hypervisors, since the
      # defaults have already been checked in the above code-block
      for os_name, os_hvp in self.new_os_hvp.items():
        for hv_name, hv_params in os_hvp.items():
          utils.ForceDictType(hv_params, constants.HVS_PARAMETER_TYPES)
          # we need to fill in the new os_hvp on top of the actual hv_p
          cluster_defaults = self.new_hvparams.get(hv_name, {})
          new_osp = objects.FillDict(cluster_defaults, hv_params)
          hv_class = hypervisor.GetHypervisor(hv_name)
          hv_class.CheckParameterSyntax(new_osp)
          _CheckHVParams(self, node_list, hv_name, new_osp)


  def Exec(self, feedback_fn):
    """Change the parameters of the cluster.

    """
    if self.op.vg_name is not None:
      new_volume = self.op.vg_name
      if not new_volume:
        new_volume = None
      if new_volume != self.cfg.GetVGName():
        self.cfg.SetVGName(new_volume)
      else:
        feedback_fn("Cluster LVM configuration already in desired"
                    " state, not changing")
    if self.op.hvparams:
      self.cluster.hvparams = self.new_hvparams
    if self.op.os_hvp:
      self.cluster.os_hvp = self.new_os_hvp
    if self.op.enabled_hypervisors is not None:
      self.cluster.hvparams = self.new_hvparams
      self.cluster.enabled_hypervisors = self.op.enabled_hypervisors
    if self.op.beparams:
      self.cluster.beparams[constants.PP_DEFAULT] = self.new_beparams
    if self.op.nicparams:
      self.cluster.nicparams[constants.PP_DEFAULT] = self.new_nicparams

    if self.op.candidate_pool_size is not None:
      self.cluster.candidate_pool_size = self.op.candidate_pool_size
      # we need to update the pool size here, otherwise the save will fail
      _AdjustCandidatePool(self, [])

    if self.op.maintain_node_health is not None:
      self.cluster.maintain_node_health = self.op.maintain_node_health

    if self.op.add_uids is not None:
      uidpool.AddToUidPool(self.cluster.uid_pool, self.op.add_uids)

    if self.op.remove_uids is not None:
      uidpool.RemoveFromUidPool(self.cluster.uid_pool, self.op.remove_uids)

    if self.op.uid_pool is not None:
      self.cluster.uid_pool = self.op.uid_pool

    self.cfg.Update(self.cluster, feedback_fn)


def _RedistributeAncillaryFiles(lu, additional_nodes=None):
  """Distribute additional files which are part of the cluster configuration.

  ConfigWriter takes care of distributing the config and ssconf files, but
  there are more files which should be distributed to all nodes. This function
  makes sure those are copied.

  @param lu: calling logical unit
  @param additional_nodes: list of nodes not in the config to distribute to

  """
  # 1. Gather target nodes
  myself = lu.cfg.GetNodeInfo(lu.cfg.GetMasterNode())
  dist_nodes = lu.cfg.GetOnlineNodeList()
  if additional_nodes is not None:
    dist_nodes.extend(additional_nodes)
  if myself.name in dist_nodes:
    dist_nodes.remove(myself.name)

  # 2. Gather files to distribute
  dist_files = set([constants.ETC_HOSTS,
                    constants.SSH_KNOWN_HOSTS_FILE,
                    constants.RAPI_CERT_FILE,
                    constants.RAPI_USERS_FILE,
                    constants.CONFD_HMAC_KEY,
                    constants.CLUSTER_DOMAIN_SECRET_FILE,
                   ])

  enabled_hypervisors = lu.cfg.GetClusterInfo().enabled_hypervisors
  for hv_name in enabled_hypervisors:
    hv_class = hypervisor.GetHypervisor(hv_name)
    dist_files.update(hv_class.GetAncillaryFiles())

  # 3. Perform the files upload
  for fname in dist_files:
    if os.path.exists(fname):
      result = lu.rpc.call_upload_file(dist_nodes, fname)
      for to_node, to_result in result.items():
        msg = to_result.fail_msg
        if msg:
          msg = ("Copy of file %s to node %s failed: %s" %
                 (fname, to_node, msg))
          lu.proc.LogWarning(msg)


class LURedistributeConfig(NoHooksLU):
  """Force the redistribution of cluster configuration.

  This is a very simple LU.

  """
  _OP_REQP = []
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {
      locking.LEVEL_NODE: locking.ALL_SET,
    }
    self.share_locks[locking.LEVEL_NODE] = 1

  def CheckPrereq(self):
    """Check prerequisites.

    """

  def Exec(self, feedback_fn):
    """Redistribute the configuration.

    """
    self.cfg.Update(self.cfg.GetClusterInfo(), feedback_fn)
    _RedistributeAncillaryFiles(self)


def _WaitForSync(lu, instance, disks=None, oneshot=False):
  """Sleep and poll for an instance's disk to sync.

  """
  if not instance.disks or disks is not None and not disks:
    return True

  disks = _ExpandCheckDisks(instance, disks)

  if not oneshot:
    lu.proc.LogInfo("Waiting for instance %s to sync disks." % instance.name)

  node = instance.primary_node

  for dev in disks:
    lu.cfg.SetDiskID(dev, node)

  # TODO: Convert to utils.Retry

  retries = 0
  degr_retries = 10 # in seconds, as we sleep 1 second each time
  while True:
    max_time = 0
    done = True
    cumul_degraded = False
    rstats = lu.rpc.call_blockdev_getmirrorstatus(node, disks)
    msg = rstats.fail_msg
    if msg:
      lu.LogWarning("Can't get any data from node %s: %s", node, msg)
      retries += 1
      if retries >= 10:
        raise errors.RemoteError("Can't contact node %s for mirror data,"
                                 " aborting." % node)
      time.sleep(6)
      continue
    rstats = rstats.payload
    retries = 0
    for i, mstat in enumerate(rstats):
      if mstat is None:
        lu.LogWarning("Can't compute data for node %s/%s",
                           node, disks[i].iv_name)
        continue

      cumul_degraded = (cumul_degraded or
                        (mstat.is_degraded and mstat.sync_percent is None))
      if mstat.sync_percent is not None:
        done = False
        if mstat.estimated_time is not None:
          rem_time = ("%s remaining (estimated)" %
                      utils.FormatSeconds(mstat.estimated_time))
          max_time = mstat.estimated_time
        else:
          rem_time = "no time estimate"
        lu.proc.LogInfo("- device %s: %5.2f%% done, %s" %
                        (disks[i].iv_name, mstat.sync_percent, rem_time))

    # if we're done but degraded, let's do a few small retries, to
    # make sure we see a stable and not transient situation; therefore
    # we force restart of the loop
    if (done or oneshot) and cumul_degraded and degr_retries > 0:
      logging.info("Degraded disks found, %d retries left", degr_retries)
      degr_retries -= 1
      time.sleep(1)
      continue

    if done or oneshot:
      break

    time.sleep(min(60, max_time))

  if done:
    lu.proc.LogInfo("Instance %s's disks are in sync." % instance.name)
  return not cumul_degraded


def _CheckDiskConsistency(lu, dev, node, on_primary, ldisk=False):
  """Check that mirrors are not degraded.

  The ldisk parameter, if True, will change the test from the
  is_degraded attribute (which represents overall non-ok status for
  the device(s)) to the ldisk (representing the local storage status).

  """
  lu.cfg.SetDiskID(dev, node)

  result = True

  if on_primary or dev.AssembleOnSecondary():
    rstats = lu.rpc.call_blockdev_find(node, dev)
    msg = rstats.fail_msg
    if msg:
      lu.LogWarning("Can't find disk on node %s: %s", node, msg)
      result = False
    elif not rstats.payload:
      lu.LogWarning("Can't find disk on node %s", node)
      result = False
    else:
      if ldisk:
        result = result and rstats.payload.ldisk_status == constants.LDS_OKAY
      else:
        result = result and not rstats.payload.is_degraded

  if dev.children:
    for child in dev.children:
      result = result and _CheckDiskConsistency(lu, child, node, on_primary)

  return result


class LUDiagnoseOS(NoHooksLU):
  """Logical unit for OS diagnose/query.

  """
  _OP_REQP = ["output_fields", "names"]
  REQ_BGL = False
  _FIELDS_STATIC = utils.FieldSet()
  _FIELDS_DYNAMIC = utils.FieldSet("name", "valid", "node_status", "variants")
  # Fields that need calculation of global os validity
  _FIELDS_NEEDVALID = frozenset(["valid", "variants"])

  def ExpandNames(self):
    if self.op.names:
      raise errors.OpPrereqError("Selective OS query not supported",
                                 errors.ECODE_INVAL)

    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=self._FIELDS_DYNAMIC,
                       selected=self.op.output_fields)

    # Lock all nodes, in shared mode
    # Temporary removal of locks, should be reverted later
    # TODO: reintroduce locks when they are lighter-weight
    self.needed_locks = {}
    #self.share_locks[locking.LEVEL_NODE] = 1
    #self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

  def CheckPrereq(self):
    """Check prerequisites.

    """

  @staticmethod
  def _DiagnoseByOS(rlist):
    """Remaps a per-node return list into an a per-os per-node dictionary

    @param rlist: a map with node names as keys and OS objects as values

    @rtype: dict
    @return: a dictionary with osnames as keys and as value another map, with
        nodes as keys and tuples of (path, status, diagnose) as values, eg::

          {"debian-etch": {"node1": [(/usr/lib/..., True, ""),
                                     (/srv/..., False, "invalid api")],
                           "node2": [(/srv/..., True, "")]}
          }

    """
    all_os = {}
    # we build here the list of nodes that didn't fail the RPC (at RPC
    # level), so that nodes with a non-responding node daemon don't
    # make all OSes invalid
    good_nodes = [node_name for node_name in rlist
                  if not rlist[node_name].fail_msg]
    for node_name, nr in rlist.items():
      if nr.fail_msg or not nr.payload:
        continue
      for name, path, status, diagnose, variants in nr.payload:
        if name not in all_os:
          # build a list of nodes for this os containing empty lists
          # for each node in node_list
          all_os[name] = {}
          for nname in good_nodes:
            all_os[name][nname] = []
        all_os[name][node_name].append((path, status, diagnose, variants))
    return all_os

  def Exec(self, feedback_fn):
    """Compute the list of OSes.

    """
    valid_nodes = [node for node in self.cfg.GetOnlineNodeList()]
    node_data = self.rpc.call_os_diagnose(valid_nodes)
    pol = self._DiagnoseByOS(node_data)
    output = []
    calc_valid = self._FIELDS_NEEDVALID.intersection(self.op.output_fields)
    calc_variants = "variants" in self.op.output_fields

    for os_name, os_data in pol.items():
      row = []
      if calc_valid:
        valid = True
        variants = None
        for osl in os_data.values():
          valid = bool(valid and osl and osl[0][1])
          if not valid:
            variants = set()
            break
          if calc_variants:
            node_variants = osl[0][3]
            if variants is None:
              variants = set(node_variants)
            else:
              variants.intersection_update(node_variants)

      for field in self.op.output_fields:
        if field == "name":
          val = os_name
        elif field == "valid":
          val = valid
        elif field == "node_status":
          # this is just a copy of the dict
          val = {}
          for node_name, nos_list in os_data.items():
            val[node_name] = nos_list
        elif field == "variants":
          val = list(variants)
        else:
          raise errors.ParameterError(field)
        row.append(val)
      output.append(row)

    return output


class LURemoveNode(LogicalUnit):
  """Logical unit for removing a node.

  """
  HPATH = "node-remove"
  HTYPE = constants.HTYPE_NODE
  _OP_REQP = ["node_name"]

  def BuildHooksEnv(self):
    """Build hooks env.

    This doesn't run on the target node in the pre phase as a failed
    node would then be impossible to remove.

    """
    env = {
      "OP_TARGET": self.op.node_name,
      "NODE_NAME": self.op.node_name,
      }
    all_nodes = self.cfg.GetNodeList()
    try:
      all_nodes.remove(self.op.node_name)
    except ValueError:
      logging.warning("Node %s which is about to be removed not found"
                      " in the all nodes list", self.op.node_name)
    return env, all_nodes, all_nodes

  def CheckPrereq(self):
    """Check prerequisites.

    This checks:
     - the node exists in the configuration
     - it does not have primary or secondary instances
     - it's not the master

    Any errors are signaled by raising errors.OpPrereqError.

    """
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)
    node = self.cfg.GetNodeInfo(self.op.node_name)
    assert node is not None

    instance_list = self.cfg.GetInstanceList()

    masternode = self.cfg.GetMasterNode()
    if node.name == masternode:
      raise errors.OpPrereqError("Node is the master node,"
                                 " you need to failover first.",
                                 errors.ECODE_INVAL)

    for instance_name in instance_list:
      instance = self.cfg.GetInstanceInfo(instance_name)
      if node.name in instance.all_nodes:
        raise errors.OpPrereqError("Instance %s is still running on the node,"
                                   " please remove first." % instance_name,
                                   errors.ECODE_INVAL)
    self.op.node_name = node.name
    self.node = node

  def Exec(self, feedback_fn):
    """Removes the node from the cluster.

    """
    node = self.node
    logging.info("Stopping the node daemon and removing configs from node %s",
                 node.name)

    modify_ssh_setup = self.cfg.GetClusterInfo().modify_ssh_setup

    # Promote nodes to master candidate as needed
    _AdjustCandidatePool(self, exceptions=[node.name])
    self.context.RemoveNode(node.name)

    # Run post hooks on the node before it's removed
    hm = self.proc.hmclass(self.rpc.call_hooks_runner, self)
    try:
      hm.RunPhase(constants.HOOKS_PHASE_POST, [node.name])
    except:
      # pylint: disable-msg=W0702
      self.LogWarning("Errors occurred running hooks on %s" % node.name)

    result = self.rpc.call_node_leave_cluster(node.name, modify_ssh_setup)
    msg = result.fail_msg
    if msg:
      self.LogWarning("Errors encountered on the remote node while leaving"
                      " the cluster: %s", msg)

    # Remove node from our /etc/hosts
    if self.cfg.GetClusterInfo().modify_etc_hosts:
      # FIXME: this should be done via an rpc call to node daemon
      utils.RemoveHostFromEtcHosts(node.name)
      _RedistributeAncillaryFiles(self)


class LUQueryNodes(NoHooksLU):
  """Logical unit for querying nodes.

  """
  # pylint: disable-msg=W0142
  _OP_REQP = ["output_fields", "names", "use_locking"]
  REQ_BGL = False

  _SIMPLE_FIELDS = ["name", "serial_no", "ctime", "mtime", "uuid",
                    "master_candidate", "offline", "drained"]

  _FIELDS_DYNAMIC = utils.FieldSet(
    "dtotal", "dfree",
    "mtotal", "mnode", "mfree",
    "bootid",
    "ctotal", "cnodes", "csockets",
    )

  _FIELDS_STATIC = utils.FieldSet(*[
    "pinst_cnt", "sinst_cnt",
    "pinst_list", "sinst_list",
    "pip", "sip", "tags",
    "master",
    "role"] + _SIMPLE_FIELDS
    )

  def ExpandNames(self):
    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=self._FIELDS_DYNAMIC,
                       selected=self.op.output_fields)

    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1

    if self.op.names:
      self.wanted = _GetWantedNodes(self, self.op.names)
    else:
      self.wanted = locking.ALL_SET

    self.do_node_query = self._FIELDS_STATIC.NonMatching(self.op.output_fields)
    self.do_locking = self.do_node_query and self.op.use_locking
    if self.do_locking:
      # if we don't request only static fields, we need to lock the nodes
      self.needed_locks[locking.LEVEL_NODE] = self.wanted

  def CheckPrereq(self):
    """Check prerequisites.

    """
    # The validation of the node list is done in the _GetWantedNodes,
    # if non empty, and if empty, there's no validation to do
    pass

  def Exec(self, feedback_fn):
    """Computes the list of nodes and their attributes.

    """
    all_info = self.cfg.GetAllNodesInfo()
    if self.do_locking:
      nodenames = self.acquired_locks[locking.LEVEL_NODE]
    elif self.wanted != locking.ALL_SET:
      nodenames = self.wanted
      missing = set(nodenames).difference(all_info.keys())
      if missing:
        raise errors.OpExecError(
          "Some nodes were removed before retrieving their data: %s" % missing)
    else:
      nodenames = all_info.keys()

    nodenames = utils.NiceSort(nodenames)
    nodelist = [all_info[name] for name in nodenames]

    # begin data gathering

    if self.do_node_query:
      live_data = {}
      node_data = self.rpc.call_node_info(nodenames, self.cfg.GetVGName(),
                                          self.cfg.GetHypervisorType())
      for name in nodenames:
        nodeinfo = node_data[name]
        if not nodeinfo.fail_msg and nodeinfo.payload:
          nodeinfo = nodeinfo.payload
          fn = utils.TryConvert
          live_data[name] = {
            "mtotal": fn(int, nodeinfo.get('memory_total', None)),
            "mnode": fn(int, nodeinfo.get('memory_dom0', None)),
            "mfree": fn(int, nodeinfo.get('memory_free', None)),
            "dtotal": fn(int, nodeinfo.get('vg_size', None)),
            "dfree": fn(int, nodeinfo.get('vg_free', None)),
            "ctotal": fn(int, nodeinfo.get('cpu_total', None)),
            "bootid": nodeinfo.get('bootid', None),
            "cnodes": fn(int, nodeinfo.get('cpu_nodes', None)),
            "csockets": fn(int, nodeinfo.get('cpu_sockets', None)),
            }
        else:
          live_data[name] = {}
    else:
      live_data = dict.fromkeys(nodenames, {})

    node_to_primary = dict([(name, set()) for name in nodenames])
    node_to_secondary = dict([(name, set()) for name in nodenames])

    inst_fields = frozenset(("pinst_cnt", "pinst_list",
                             "sinst_cnt", "sinst_list"))
    if inst_fields & frozenset(self.op.output_fields):
      inst_data = self.cfg.GetAllInstancesInfo()

      for inst in inst_data.values():
        if inst.primary_node in node_to_primary:
          node_to_primary[inst.primary_node].add(inst.name)
        for secnode in inst.secondary_nodes:
          if secnode in node_to_secondary:
            node_to_secondary[secnode].add(inst.name)

    master_node = self.cfg.GetMasterNode()

    # end data gathering

    output = []
    for node in nodelist:
      node_output = []
      for field in self.op.output_fields:
        if field in self._SIMPLE_FIELDS:
          val = getattr(node, field)
        elif field == "pinst_list":
          val = list(node_to_primary[node.name])
        elif field == "sinst_list":
          val = list(node_to_secondary[node.name])
        elif field == "pinst_cnt":
          val = len(node_to_primary[node.name])
        elif field == "sinst_cnt":
          val = len(node_to_secondary[node.name])
        elif field == "pip":
          val = node.primary_ip
        elif field == "sip":
          val = node.secondary_ip
        elif field == "tags":
          val = list(node.GetTags())
        elif field == "master":
          val = node.name == master_node
        elif self._FIELDS_DYNAMIC.Matches(field):
          val = live_data[node.name].get(field, None)
        elif field == "role":
          if node.name == master_node:
            val = "M"
          elif node.master_candidate:
            val = "C"
          elif node.drained:
            val = "D"
          elif node.offline:
            val = "O"
          else:
            val = "R"
        else:
          raise errors.ParameterError(field)
        node_output.append(val)
      output.append(node_output)

    return output


class LUQueryNodeVolumes(NoHooksLU):
  """Logical unit for getting volumes on node(s).

  """
  _OP_REQP = ["nodes", "output_fields"]
  REQ_BGL = False
  _FIELDS_DYNAMIC = utils.FieldSet("phys", "vg", "name", "size", "instance")
  _FIELDS_STATIC = utils.FieldSet("node")

  def ExpandNames(self):
    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=self._FIELDS_DYNAMIC,
                       selected=self.op.output_fields)

    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1
    if not self.op.nodes:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET
    else:
      self.needed_locks[locking.LEVEL_NODE] = \
        _GetWantedNodes(self, self.op.nodes)

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the fields required are valid output fields.

    """
    self.nodes = self.acquired_locks[locking.LEVEL_NODE]

  def Exec(self, feedback_fn):
    """Computes the list of nodes and their attributes.

    """
    nodenames = self.nodes
    volumes = self.rpc.call_node_volumes(nodenames)

    ilist = [self.cfg.GetInstanceInfo(iname) for iname
             in self.cfg.GetInstanceList()]

    lv_by_node = dict([(inst, inst.MapLVsByNode()) for inst in ilist])

    output = []
    for node in nodenames:
      nresult = volumes[node]
      if nresult.offline:
        continue
      msg = nresult.fail_msg
      if msg:
        self.LogWarning("Can't compute volume data on node %s: %s", node, msg)
        continue

      node_vols = nresult.payload[:]
      node_vols.sort(key=lambda vol: vol['dev'])

      for vol in node_vols:
        node_output = []
        for field in self.op.output_fields:
          if field == "node":
            val = node
          elif field == "phys":
            val = vol['dev']
          elif field == "vg":
            val = vol['vg']
          elif field == "name":
            val = vol['name']
          elif field == "size":
            val = int(float(vol['size']))
          elif field == "instance":
            for inst in ilist:
              if node not in lv_by_node[inst]:
                continue
              if vol['name'] in lv_by_node[inst][node]:
                val = inst.name
                break
            else:
              val = '-'
          else:
            raise errors.ParameterError(field)
          node_output.append(str(val))

        output.append(node_output)

    return output


class LUQueryNodeStorage(NoHooksLU):
  """Logical unit for getting information on storage units on node(s).

  """
  _OP_REQP = ["nodes", "storage_type", "output_fields"]
  REQ_BGL = False
  _FIELDS_STATIC = utils.FieldSet(constants.SF_NODE)

  def CheckArguments(self):
    _CheckStorageType(self.op.storage_type)

    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=utils.FieldSet(*constants.VALID_STORAGE_FIELDS),
                       selected=self.op.output_fields)

  def ExpandNames(self):
    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1

    if self.op.nodes:
      self.needed_locks[locking.LEVEL_NODE] = \
        _GetWantedNodes(self, self.op.nodes)
    else:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the fields required are valid output fields.

    """
    self.op.name = getattr(self.op, "name", None)

    self.nodes = self.acquired_locks[locking.LEVEL_NODE]

  def Exec(self, feedback_fn):
    """Computes the list of nodes and their attributes.

    """
    # Always get name to sort by
    if constants.SF_NAME in self.op.output_fields:
      fields = self.op.output_fields[:]
    else:
      fields = [constants.SF_NAME] + self.op.output_fields

    # Never ask for node or type as it's only known to the LU
    for extra in [constants.SF_NODE, constants.SF_TYPE]:
      while extra in fields:
        fields.remove(extra)

    field_idx = dict([(name, idx) for (idx, name) in enumerate(fields)])
    name_idx = field_idx[constants.SF_NAME]

    st_args = _GetStorageTypeArgs(self.cfg, self.op.storage_type)
    data = self.rpc.call_storage_list(self.nodes,
                                      self.op.storage_type, st_args,
                                      self.op.name, fields)

    result = []

    for node in utils.NiceSort(self.nodes):
      nresult = data[node]
      if nresult.offline:
        continue

      msg = nresult.fail_msg
      if msg:
        self.LogWarning("Can't get storage data from node %s: %s", node, msg)
        continue

      rows = dict([(row[name_idx], row) for row in nresult.payload])

      for name in utils.NiceSort(rows.keys()):
        row = rows[name]

        out = []

        for field in self.op.output_fields:
          if field == constants.SF_NODE:
            val = node
          elif field == constants.SF_TYPE:
            val = self.op.storage_type
          elif field in field_idx:
            val = row[field_idx[field]]
          else:
            raise errors.ParameterError(field)

          out.append(val)

        result.append(out)

    return result


class LUModifyNodeStorage(NoHooksLU):
  """Logical unit for modifying a storage volume on a node.

  """
  _OP_REQP = ["node_name", "storage_type", "name", "changes"]
  REQ_BGL = False

  def CheckArguments(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)

    _CheckStorageType(self.op.storage_type)

  def ExpandNames(self):
    self.needed_locks = {
      locking.LEVEL_NODE: self.op.node_name,
      }

  def CheckPrereq(self):
    """Check prerequisites.

    """
    storage_type = self.op.storage_type

    try:
      modifiable = constants.MODIFIABLE_STORAGE_FIELDS[storage_type]
    except KeyError:
      raise errors.OpPrereqError("Storage units of type '%s' can not be"
                                 " modified" % storage_type,
                                 errors.ECODE_INVAL)

    diff = set(self.op.changes.keys()) - modifiable
    if diff:
      raise errors.OpPrereqError("The following fields can not be modified for"
                                 " storage units of type '%s': %r" %
                                 (storage_type, list(diff)),
                                 errors.ECODE_INVAL)

  def Exec(self, feedback_fn):
    """Computes the list of nodes and their attributes.

    """
    st_args = _GetStorageTypeArgs(self.cfg, self.op.storage_type)
    result = self.rpc.call_storage_modify(self.op.node_name,
                                          self.op.storage_type, st_args,
                                          self.op.name, self.op.changes)
    result.Raise("Failed to modify storage unit '%s' on %s" %
                 (self.op.name, self.op.node_name))


class LUAddNode(LogicalUnit):
  """Logical unit for adding node to the cluster.

  """
  HPATH = "node-add"
  HTYPE = constants.HTYPE_NODE
  _OP_REQP = ["node_name"]

  def CheckArguments(self):
    # validate/normalize the node name
    self.op.node_name = utils.HostInfo.NormalizeName(self.op.node_name)

  def BuildHooksEnv(self):
    """Build hooks env.

    This will run on all nodes before, and on all nodes + the new node after.

    """
    env = {
      "OP_TARGET": self.op.node_name,
      "NODE_NAME": self.op.node_name,
      "NODE_PIP": self.op.primary_ip,
      "NODE_SIP": self.op.secondary_ip,
      }
    nodes_0 = self.cfg.GetNodeList()
    nodes_1 = nodes_0 + [self.op.node_name, ]
    return env, nodes_0, nodes_1

  def CheckPrereq(self):
    """Check prerequisites.

    This checks:
     - the new node is not already in the config
     - it is resolvable
     - its parameters (single/dual homed) matches the cluster

    Any errors are signaled by raising errors.OpPrereqError.

    """
    node_name = self.op.node_name
    cfg = self.cfg

    dns_data = utils.GetHostInfo(node_name)

    node = dns_data.name
    primary_ip = self.op.primary_ip = dns_data.ip
    secondary_ip = getattr(self.op, "secondary_ip", None)
    if secondary_ip is None:
      secondary_ip = primary_ip
    if not utils.IsValidIP(secondary_ip):
      raise errors.OpPrereqError("Invalid secondary IP given",
                                 errors.ECODE_INVAL)
    self.op.secondary_ip = secondary_ip

    node_list = cfg.GetNodeList()
    if not self.op.readd and node in node_list:
      raise errors.OpPrereqError("Node %s is already in the configuration" %
                                 node, errors.ECODE_EXISTS)
    elif self.op.readd and node not in node_list:
      raise errors.OpPrereqError("Node %s is not in the configuration" % node,
                                 errors.ECODE_NOENT)

    self.changed_primary_ip = False

    for existing_node_name in node_list:
      existing_node = cfg.GetNodeInfo(existing_node_name)

      if self.op.readd and node == existing_node_name:
        if existing_node.secondary_ip != secondary_ip:
          raise errors.OpPrereqError("Readded node doesn't have the same IP"
                                     " address configuration as before",
                                     errors.ECODE_INVAL)
        if existing_node.primary_ip != primary_ip:
          self.changed_primary_ip = True

        continue

      if (existing_node.primary_ip == primary_ip or
          existing_node.secondary_ip == primary_ip or
          existing_node.primary_ip == secondary_ip or
          existing_node.secondary_ip == secondary_ip):
        raise errors.OpPrereqError("New node ip address(es) conflict with"
                                   " existing node %s" % existing_node.name,
                                   errors.ECODE_NOTUNIQUE)

    # check that the type of the node (single versus dual homed) is the
    # same as for the master
    myself = cfg.GetNodeInfo(self.cfg.GetMasterNode())
    master_singlehomed = myself.secondary_ip == myself.primary_ip
    newbie_singlehomed = secondary_ip == primary_ip
    if master_singlehomed != newbie_singlehomed:
      if master_singlehomed:
        raise errors.OpPrereqError("The master has no private ip but the"
                                   " new node has one",
                                   errors.ECODE_INVAL)
      else:
        raise errors.OpPrereqError("The master has a private ip but the"
                                   " new node doesn't have one",
                                   errors.ECODE_INVAL)

    # checks reachability
    if not utils.TcpPing(primary_ip, constants.DEFAULT_NODED_PORT):
      raise errors.OpPrereqError("Node not reachable by ping",
                                 errors.ECODE_ENVIRON)

    if not newbie_singlehomed:
      # check reachability from my secondary ip to newbie's secondary ip
      if not utils.TcpPing(secondary_ip, constants.DEFAULT_NODED_PORT,
                           source=myself.secondary_ip):
        raise errors.OpPrereqError("Node secondary ip not reachable by TCP"
                                   " based ping to noded port",
                                   errors.ECODE_ENVIRON)

    if self.op.readd:
      exceptions = [node]
    else:
      exceptions = []

    self.master_candidate = _DecideSelfPromotion(self, exceptions=exceptions)

    if self.op.readd:
      self.new_node = self.cfg.GetNodeInfo(node)
      assert self.new_node is not None, "Can't retrieve locked node %s" % node
    else:
      self.new_node = objects.Node(name=node,
                                   primary_ip=primary_ip,
                                   secondary_ip=secondary_ip,
                                   master_candidate=self.master_candidate,
                                   offline=False, drained=False)

  def Exec(self, feedback_fn):
    """Adds the new node to the cluster.

    """
    new_node = self.new_node
    node = new_node.name

    # for re-adds, reset the offline/drained/master-candidate flags;
    # we need to reset here, otherwise offline would prevent RPC calls
    # later in the procedure; this also means that if the re-add
    # fails, we are left with a non-offlined, broken node
    if self.op.readd:
      new_node.drained = new_node.offline = False # pylint: disable-msg=W0201
      self.LogInfo("Readding a node, the offline/drained flags were reset")
      # if we demote the node, we do cleanup later in the procedure
      new_node.master_candidate = self.master_candidate
      if self.changed_primary_ip:
        new_node.primary_ip = self.op.primary_ip

    # notify the user about any possible mc promotion
    if new_node.master_candidate:
      self.LogInfo("Node will be a master candidate")

    # check connectivity
    result = self.rpc.call_version([node])[node]
    result.Raise("Can't get version information from node %s" % node)
    if constants.PROTOCOL_VERSION == result.payload:
      logging.info("Communication to node %s fine, sw version %s match",
                   node, result.payload)
    else:
      raise errors.OpExecError("Version mismatch master version %s,"
                               " node version %s" %
                               (constants.PROTOCOL_VERSION, result.payload))

    # setup ssh on node
    if self.cfg.GetClusterInfo().modify_ssh_setup:
      logging.info("Copy ssh key to node %s", node)
      priv_key, pub_key, _ = ssh.GetUserFiles(constants.GANETI_RUNAS)
      keyarray = []
      keyfiles = [constants.SSH_HOST_DSA_PRIV, constants.SSH_HOST_DSA_PUB,
                  constants.SSH_HOST_RSA_PRIV, constants.SSH_HOST_RSA_PUB,
                  priv_key, pub_key]

      for i in keyfiles:
        keyarray.append(utils.ReadFile(i))

      result = self.rpc.call_node_add(node, keyarray[0], keyarray[1],
                                      keyarray[2], keyarray[3], keyarray[4],
                                      keyarray[5])
      result.Raise("Cannot transfer ssh keys to the new node")

    # Add node to our /etc/hosts, and add key to known_hosts
    if self.cfg.GetClusterInfo().modify_etc_hosts:
      # FIXME: this should be done via an rpc call to node daemon
      utils.AddHostToEtcHosts(new_node.name)

    if new_node.secondary_ip != new_node.primary_ip:
      result = self.rpc.call_node_has_ip_address(new_node.name,
                                                 new_node.secondary_ip)
      result.Raise("Failure checking secondary ip on node %s" % new_node.name,
                   prereq=True, ecode=errors.ECODE_ENVIRON)
      if not result.payload:
        raise errors.OpExecError("Node claims it doesn't have the secondary ip"
                                 " you gave (%s). Please fix and re-run this"
                                 " command." % new_node.secondary_ip)

    node_verify_list = [self.cfg.GetMasterNode()]
    node_verify_param = {
      constants.NV_NODELIST: [node],
      # TODO: do a node-net-test as well?
    }

    result = self.rpc.call_node_verify(node_verify_list, node_verify_param,
                                       self.cfg.GetClusterName())
    for verifier in node_verify_list:
      result[verifier].Raise("Cannot communicate with node %s" % verifier)
      nl_payload = result[verifier].payload[constants.NV_NODELIST]
      if nl_payload:
        for failed in nl_payload:
          feedback_fn("ssh/hostname verification failed"
                      " (checking from %s): %s" %
                      (verifier, nl_payload[failed]))
        raise errors.OpExecError("ssh/hostname verification failed.")

    if self.op.readd:
      _RedistributeAncillaryFiles(self)
      self.context.ReaddNode(new_node)
      # make sure we redistribute the config
      self.cfg.Update(new_node, feedback_fn)
      # and make sure the new node will not have old files around
      if not new_node.master_candidate:
        result = self.rpc.call_node_demote_from_mc(new_node.name)
        msg = result.fail_msg
        if msg:
          self.LogWarning("Node failed to demote itself from master"
                          " candidate status: %s" % msg)
    else:
      _RedistributeAncillaryFiles(self, additional_nodes=[node])
      self.context.AddNode(new_node, self.proc.GetECId())


class LUSetNodeParams(LogicalUnit):
  """Modifies the parameters of a node.

  """
  HPATH = "node-modify"
  HTYPE = constants.HTYPE_NODE
  _OP_REQP = ["node_name"]
  REQ_BGL = False

  def CheckArguments(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)
    _CheckBooleanOpField(self.op, 'master_candidate')
    _CheckBooleanOpField(self.op, 'offline')
    _CheckBooleanOpField(self.op, 'drained')
    _CheckBooleanOpField(self.op, 'auto_promote')
    all_mods = [self.op.offline, self.op.master_candidate, self.op.drained]
    if all_mods.count(None) == 3:
      raise errors.OpPrereqError("Please pass at least one modification",
                                 errors.ECODE_INVAL)
    if all_mods.count(True) > 1:
      raise errors.OpPrereqError("Can't set the node into more than one"
                                 " state at the same time",
                                 errors.ECODE_INVAL)

    # Boolean value that tells us whether we're offlining or draining the node
    self.offline_or_drain = (self.op.offline == True or
                             self.op.drained == True)
    self.deoffline_or_drain = (self.op.offline == False or
                               self.op.drained == False)
    self.might_demote = (self.op.master_candidate == False or
                         self.offline_or_drain)

    self.lock_all = self.op.auto_promote and self.might_demote


  def ExpandNames(self):
    if self.lock_all:
      self.needed_locks = {locking.LEVEL_NODE: locking.ALL_SET}
    else:
      self.needed_locks = {locking.LEVEL_NODE: self.op.node_name}

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master node.

    """
    env = {
      "OP_TARGET": self.op.node_name,
      "MASTER_CANDIDATE": str(self.op.master_candidate),
      "OFFLINE": str(self.op.offline),
      "DRAINED": str(self.op.drained),
      }
    nl = [self.cfg.GetMasterNode(),
          self.op.node_name]
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This only checks the instance list against the existing names.

    """
    node = self.node = self.cfg.GetNodeInfo(self.op.node_name)

    if (self.op.master_candidate is not None or
        self.op.drained is not None or
        self.op.offline is not None):
      # we can't change the master's node flags
      if self.op.node_name == self.cfg.GetMasterNode():
        raise errors.OpPrereqError("The master role can be changed"
                                   " only via masterfailover",
                                   errors.ECODE_INVAL)


    if node.master_candidate and self.might_demote and not self.lock_all:
      assert not self.op.auto_promote, "auto-promote set but lock_all not"
      # check if after removing the current node, we're missing master
      # candidates
      (mc_remaining, mc_should, _) = \
          self.cfg.GetMasterCandidateStats(exceptions=[node.name])
      if mc_remaining < mc_should:
        raise errors.OpPrereqError("Not enough master candidates, please"
                                   " pass auto_promote to allow promotion",
                                   errors.ECODE_INVAL)

    if (self.op.master_candidate == True and
        ((node.offline and not self.op.offline == False) or
         (node.drained and not self.op.drained == False))):
      raise errors.OpPrereqError("Node '%s' is offline or drained, can't set"
                                 " to master_candidate" % node.name,
                                 errors.ECODE_INVAL)

    # If we're being deofflined/drained, we'll MC ourself if needed
    if (self.deoffline_or_drain and not self.offline_or_drain and not
        self.op.master_candidate == True and not node.master_candidate):
      self.op.master_candidate = _DecideSelfPromotion(self)
      if self.op.master_candidate:
        self.LogInfo("Autopromoting node to master candidate")

    return

  def Exec(self, feedback_fn):
    """Modifies a node.

    """
    node = self.node

    result = []
    changed_mc = False

    if self.op.offline is not None:
      node.offline = self.op.offline
      result.append(("offline", str(self.op.offline)))
      if self.op.offline == True:
        if node.master_candidate:
          node.master_candidate = False
          changed_mc = True
          result.append(("master_candidate", "auto-demotion due to offline"))
        if node.drained:
          node.drained = False
          result.append(("drained", "clear drained status due to offline"))

    if self.op.master_candidate is not None:
      node.master_candidate = self.op.master_candidate
      changed_mc = True
      result.append(("master_candidate", str(self.op.master_candidate)))
      if self.op.master_candidate == False:
        rrc = self.rpc.call_node_demote_from_mc(node.name)
        msg = rrc.fail_msg
        if msg:
          self.LogWarning("Node failed to demote itself: %s" % msg)

    if self.op.drained is not None:
      node.drained = self.op.drained
      result.append(("drained", str(self.op.drained)))
      if self.op.drained == True:
        if node.master_candidate:
          node.master_candidate = False
          changed_mc = True
          result.append(("master_candidate", "auto-demotion due to drain"))
          rrc = self.rpc.call_node_demote_from_mc(node.name)
          msg = rrc.fail_msg
          if msg:
            self.LogWarning("Node failed to demote itself: %s" % msg)
        if node.offline:
          node.offline = False
          result.append(("offline", "clear offline status due to drain"))

    # we locked all nodes, we adjust the CP before updating this node
    if self.lock_all:
      _AdjustCandidatePool(self, [node.name])

    # this will trigger configuration file update, if needed
    self.cfg.Update(node, feedback_fn)

    # this will trigger job queue propagation or cleanup
    if changed_mc:
      self.context.ReaddNode(node)

    return result


class LUPowercycleNode(NoHooksLU):
  """Powercycles a node.

  """
  _OP_REQP = ["node_name", "force"]
  REQ_BGL = False

  def CheckArguments(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)
    if self.op.node_name == self.cfg.GetMasterNode() and not self.op.force:
      raise errors.OpPrereqError("The node is the master and the force"
                                 " parameter was not set",
                                 errors.ECODE_INVAL)

  def ExpandNames(self):
    """Locking for PowercycleNode.

    This is a last-resort option and shouldn't block on other
    jobs. Therefore, we grab no locks.

    """
    self.needed_locks = {}

  def CheckPrereq(self):
    """Check prerequisites.

    This LU has no prereqs.

    """
    pass

  def Exec(self, feedback_fn):
    """Reboots a node.

    """
    result = self.rpc.call_node_powercycle(self.op.node_name,
                                           self.cfg.GetHypervisorType())
    result.Raise("Failed to schedule the reboot")
    return result.payload


class LUQueryClusterInfo(NoHooksLU):
  """Query cluster configuration.

  """
  _OP_REQP = []
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {}

  def CheckPrereq(self):
    """No prerequsites needed for this LU.

    """
    pass

  def Exec(self, feedback_fn):
    """Return cluster config.

    """
    cluster = self.cfg.GetClusterInfo()
    os_hvp = {}

    # Filter just for enabled hypervisors
    for os_name, hv_dict in cluster.os_hvp.items():
      os_hvp[os_name] = {}
      for hv_name, hv_params in hv_dict.items():
        if hv_name in cluster.enabled_hypervisors:
          os_hvp[os_name][hv_name] = hv_params

    result = {
      "software_version": constants.RELEASE_VERSION,
      "protocol_version": constants.PROTOCOL_VERSION,
      "config_version": constants.CONFIG_VERSION,
      "os_api_version": max(constants.OS_API_VERSIONS),
      "export_version": constants.EXPORT_VERSION,
      "architecture": (platform.architecture()[0], platform.machine()),
      "name": cluster.cluster_name,
      "master": cluster.master_node,
      "default_hypervisor": cluster.enabled_hypervisors[0],
      "enabled_hypervisors": cluster.enabled_hypervisors,
      "hvparams": dict([(hypervisor_name, cluster.hvparams[hypervisor_name])
                        for hypervisor_name in cluster.enabled_hypervisors]),
      "os_hvp": os_hvp,
      "beparams": cluster.beparams,
      "nicparams": cluster.nicparams,
      "candidate_pool_size": cluster.candidate_pool_size,
      "master_netdev": cluster.master_netdev,
      "volume_group_name": cluster.volume_group_name,
      "file_storage_dir": cluster.file_storage_dir,
      "maintain_node_health": cluster.maintain_node_health,
      "ctime": cluster.ctime,
      "mtime": cluster.mtime,
      "uuid": cluster.uuid,
      "tags": list(cluster.GetTags()),
      "uid_pool": cluster.uid_pool,
      }

    return result


class LUQueryConfigValues(NoHooksLU):
  """Return configuration values.

  """
  _OP_REQP = []
  REQ_BGL = False
  _FIELDS_DYNAMIC = utils.FieldSet()
  _FIELDS_STATIC = utils.FieldSet("cluster_name", "master_node", "drain_flag",
                                  "watcher_pause")

  def ExpandNames(self):
    self.needed_locks = {}

    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=self._FIELDS_DYNAMIC,
                       selected=self.op.output_fields)

  def CheckPrereq(self):
    """No prerequisites.

    """
    pass

  def Exec(self, feedback_fn):
    """Dump a representation of the cluster config to the standard output.

    """
    values = []
    for field in self.op.output_fields:
      if field == "cluster_name":
        entry = self.cfg.GetClusterName()
      elif field == "master_node":
        entry = self.cfg.GetMasterNode()
      elif field == "drain_flag":
        entry = os.path.exists(constants.JOB_QUEUE_DRAIN_FILE)
      elif field == "watcher_pause":
        entry = utils.ReadWatcherPauseFile(constants.WATCHER_PAUSEFILE)
      else:
        raise errors.ParameterError(field)
      values.append(entry)
    return values


class LUActivateInstanceDisks(NoHooksLU):
  """Bring up an instance's disks.

  """
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, self.instance.primary_node)
    if not hasattr(self.op, "ignore_size"):
      self.op.ignore_size = False

  def Exec(self, feedback_fn):
    """Activate the disks.

    """
    disks_ok, disks_info = \
              _AssembleInstanceDisks(self, self.instance,
                                     ignore_size=self.op.ignore_size)
    if not disks_ok:
      raise errors.OpExecError("Cannot activate block devices")

    return disks_info


def _AssembleInstanceDisks(lu, instance, disks=None, ignore_secondaries=False,
                           ignore_size=False):
  """Prepare the block devices for an instance.

  This sets up the block devices on all nodes.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type instance: L{objects.Instance}
  @param instance: the instance for whose disks we assemble
  @type disks: list of L{objects.Disk} or None
  @param disks: which disks to assemble (or all, if None)
  @type ignore_secondaries: boolean
  @param ignore_secondaries: if true, errors on secondary nodes
      won't result in an error return from the function
  @type ignore_size: boolean
  @param ignore_size: if true, the current known size of the disk
      will not be used during the disk activation, useful for cases
      when the size is wrong
  @return: False if the operation failed, otherwise a list of
      (host, instance_visible_name, node_visible_name)
      with the mapping from node devices to instance devices

  """
  device_info = []
  disks_ok = True
  iname = instance.name
  disks = _ExpandCheckDisks(instance, disks)

  # With the two passes mechanism we try to reduce the window of
  # opportunity for the race condition of switching DRBD to primary
  # before handshaking occured, but we do not eliminate it

  # The proper fix would be to wait (with some limits) until the
  # connection has been made and drbd transitions from WFConnection
  # into any other network-connected state (Connected, SyncTarget,
  # SyncSource, etc.)

  # 1st pass, assemble on all nodes in secondary mode
  for inst_disk in disks:
    for node, node_disk in inst_disk.ComputeNodeTree(instance.primary_node):
      if ignore_size:
        node_disk = node_disk.Copy()
        node_disk.UnsetSize()
      lu.cfg.SetDiskID(node_disk, node)
      result = lu.rpc.call_blockdev_assemble(node, node_disk, iname, False)
      msg = result.fail_msg
      if msg:
        lu.proc.LogWarning("Could not prepare block device %s on node %s"
                           " (is_primary=False, pass=1): %s",
                           inst_disk.iv_name, node, msg)
        if not ignore_secondaries:
          disks_ok = False

  # FIXME: race condition on drbd migration to primary

  # 2nd pass, do only the primary node
  for inst_disk in disks:
    dev_path = None

    for node, node_disk in inst_disk.ComputeNodeTree(instance.primary_node):
      if node != instance.primary_node:
        continue
      if ignore_size:
        node_disk = node_disk.Copy()
        node_disk.UnsetSize()
      lu.cfg.SetDiskID(node_disk, node)
      result = lu.rpc.call_blockdev_assemble(node, node_disk, iname, True)
      msg = result.fail_msg
      if msg:
        lu.proc.LogWarning("Could not prepare block device %s on node %s"
                           " (is_primary=True, pass=2): %s",
                           inst_disk.iv_name, node, msg)
        disks_ok = False
      else:
        dev_path = result.payload

    device_info.append((instance.primary_node, inst_disk.iv_name, dev_path))

  # leave the disks configured for the primary node
  # this is a workaround that would be fixed better by
  # improving the logical/physical id handling
  for disk in disks:
    lu.cfg.SetDiskID(disk, instance.primary_node)

  return disks_ok, device_info


def _StartInstanceDisks(lu, instance, force):
  """Start the disks of an instance.

  """
  disks_ok, _ = _AssembleInstanceDisks(lu, instance,
                                           ignore_secondaries=force)
  if not disks_ok:
    _ShutdownInstanceDisks(lu, instance)
    if force is not None and not force:
      lu.proc.LogWarning("", hint="If the message above refers to a"
                         " secondary node,"
                         " you can retry the operation using '--force'.")
    raise errors.OpExecError("Disk consistency error")


class LUDeactivateInstanceDisks(NoHooksLU):
  """Shutdown an instance's disks.

  """
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

  def Exec(self, feedback_fn):
    """Deactivate the disks

    """
    instance = self.instance
    _SafeShutdownInstanceDisks(self, instance)


def _SafeShutdownInstanceDisks(lu, instance, disks=None):
  """Shutdown block devices of an instance.

  This function checks if an instance is running, before calling
  _ShutdownInstanceDisks.

  """
  _CheckInstanceDown(lu, instance, "cannot shutdown disks")
  _ShutdownInstanceDisks(lu, instance, disks=disks)


def _ExpandCheckDisks(instance, disks):
  """Return the instance disks selected by the disks list

  @type disks: list of L{objects.Disk} or None
  @param disks: selected disks
  @rtype: list of L{objects.Disk}
  @return: selected instance disks to act on

  """
  if disks is None:
    return instance.disks
  else:
    if not set(disks).issubset(instance.disks):
      raise errors.ProgrammerError("Can only act on disks belonging to the"
                                   " target instance")
    return disks


def _ShutdownInstanceDisks(lu, instance, disks=None, ignore_primary=False):
  """Shutdown block devices of an instance.

  This does the shutdown on all nodes of the instance.

  If the ignore_primary is false, errors on the primary node are
  ignored.

  """
  all_result = True
  disks = _ExpandCheckDisks(instance, disks)

  for disk in disks:
    for node, top_disk in disk.ComputeNodeTree(instance.primary_node):
      lu.cfg.SetDiskID(top_disk, node)
      result = lu.rpc.call_blockdev_shutdown(node, top_disk)
      msg = result.fail_msg
      if msg:
        lu.LogWarning("Could not shutdown block device %s on node %s: %s",
                      disk.iv_name, node, msg)
        if not ignore_primary or node != instance.primary_node:
          all_result = False
  return all_result


def _CheckNodeFreeMemory(lu, node, reason, requested, hypervisor_name):
  """Checks if a node has enough free memory.

  This function check if a given node has the needed amount of free
  memory. In case the node has less memory or we cannot get the
  information from the node, this function raise an OpPrereqError
  exception.

  @type lu: C{LogicalUnit}
  @param lu: a logical unit from which we get configuration data
  @type node: C{str}
  @param node: the node to check
  @type reason: C{str}
  @param reason: string to use in the error message
  @type requested: C{int}
  @param requested: the amount of memory in MiB to check for
  @type hypervisor_name: C{str}
  @param hypervisor_name: the hypervisor to ask for memory stats
  @raise errors.OpPrereqError: if the node doesn't have enough memory, or
      we cannot check the node

  """
  nodeinfo = lu.rpc.call_node_info([node], lu.cfg.GetVGName(), hypervisor_name)
  nodeinfo[node].Raise("Can't get data from node %s" % node,
                       prereq=True, ecode=errors.ECODE_ENVIRON)
  free_mem = nodeinfo[node].payload.get('memory_free', None)
  if not isinstance(free_mem, int):
    raise errors.OpPrereqError("Can't compute free memory on node %s, result"
                               " was '%s'" % (node, free_mem),
                               errors.ECODE_ENVIRON)
  if requested > free_mem:
    raise errors.OpPrereqError("Not enough memory on node %s for %s:"
                               " needed %s MiB, available %s MiB" %
                               (node, reason, requested, free_mem),
                               errors.ECODE_NORES)


def _CheckNodesFreeDisk(lu, nodenames, requested):
  """Checks if nodes have enough free disk space in the default VG.

  This function check if all given nodes have the needed amount of
  free disk. In case any node has less disk or we cannot get the
  information from the node, this function raise an OpPrereqError
  exception.

  @type lu: C{LogicalUnit}
  @param lu: a logical unit from which we get configuration data
  @type nodenames: C{list}
  @param nodenames: the list of node names to check
  @type requested: C{int}
  @param requested: the amount of disk in MiB to check for
  @raise errors.OpPrereqError: if the node doesn't have enough disk, or
      we cannot check the node

  """
  nodeinfo = lu.rpc.call_node_info(nodenames, lu.cfg.GetVGName(),
                                   lu.cfg.GetHypervisorType())
  for node in nodenames:
    info = nodeinfo[node]
    info.Raise("Cannot get current information from node %s" % node,
               prereq=True, ecode=errors.ECODE_ENVIRON)
    vg_free = info.payload.get("vg_free", None)
    if not isinstance(vg_free, int):
      raise errors.OpPrereqError("Can't compute free disk space on node %s,"
                                 " result was '%s'" % (node, vg_free),
                                 errors.ECODE_ENVIRON)
    if requested > vg_free:
      raise errors.OpPrereqError("Not enough disk space on target node %s:"
                                 " required %d MiB, available %d MiB" %
                                 (node, requested, vg_free),
                                 errors.ECODE_NORES)


class LUStartupInstance(LogicalUnit):
  """Starts an instance.

  """
  HPATH = "instance-start"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "force"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = {
      "FORCE": self.op.force,
      }
    env.update(_BuildInstanceHookEnvByObject(self, self.instance))
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

    # extra beparams
    self.beparams = getattr(self.op, "beparams", {})
    if self.beparams:
      if not isinstance(self.beparams, dict):
        raise errors.OpPrereqError("Invalid beparams passed: %s, expected"
                                   " dict" % (type(self.beparams), ),
                                   errors.ECODE_INVAL)
      # fill the beparams dict
      utils.ForceDictType(self.beparams, constants.BES_PARAMETER_TYPES)
      self.op.beparams = self.beparams

    # extra hvparams
    self.hvparams = getattr(self.op, "hvparams", {})
    if self.hvparams:
      if not isinstance(self.hvparams, dict):
        raise errors.OpPrereqError("Invalid hvparams passed: %s, expected"
                                   " dict" % (type(self.hvparams), ),
                                   errors.ECODE_INVAL)

      # check hypervisor parameter syntax (locally)
      cluster = self.cfg.GetClusterInfo()
      utils.ForceDictType(self.hvparams, constants.HVS_PARAMETER_TYPES)
      filled_hvp = cluster.FillHV(instance)
      filled_hvp.update(self.hvparams)
      hv_type = hypervisor.GetHypervisor(instance.hypervisor)
      hv_type.CheckParameterSyntax(filled_hvp)
      _CheckHVParams(self, instance.all_nodes, instance.hypervisor, filled_hvp)
      self.op.hvparams = self.hvparams

    _CheckNodeOnline(self, instance.primary_node)

    bep = self.cfg.GetClusterInfo().FillBE(instance)
    # check bridges existence
    _CheckInstanceBridgesExist(self, instance)

    remote_info = self.rpc.call_instance_info(instance.primary_node,
                                              instance.name,
                                              instance.hypervisor)
    remote_info.Raise("Error checking node %s" % instance.primary_node,
                      prereq=True, ecode=errors.ECODE_ENVIRON)
    if not remote_info.payload: # not running already
      _CheckNodeFreeMemory(self, instance.primary_node,
                           "starting instance %s" % instance.name,
                           bep[constants.BE_MEMORY], instance.hypervisor)

  def Exec(self, feedback_fn):
    """Start the instance.

    """
    instance = self.instance
    force = self.op.force

    self.cfg.MarkInstanceUp(instance.name)

    node_current = instance.primary_node

    _StartInstanceDisks(self, instance, force)

    result = self.rpc.call_instance_start(node_current, instance,
                                          self.hvparams, self.beparams)
    msg = result.fail_msg
    if msg:
      _ShutdownInstanceDisks(self, instance)
      raise errors.OpExecError("Could not start instance: %s" % msg)


class LURebootInstance(LogicalUnit):
  """Reboot an instance.

  """
  HPATH = "instance-reboot"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "ignore_secondaries", "reboot_type"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    self.shutdown_timeout = getattr(self.op, "shutdown_timeout",
                                    constants.DEFAULT_SHUTDOWN_TIMEOUT)

  def ExpandNames(self):
    if self.op.reboot_type not in [constants.INSTANCE_REBOOT_SOFT,
                                   constants.INSTANCE_REBOOT_HARD,
                                   constants.INSTANCE_REBOOT_FULL]:
      raise errors.ParameterError("reboot type not in [%s, %s, %s]" %
                                  (constants.INSTANCE_REBOOT_SOFT,
                                   constants.INSTANCE_REBOOT_HARD,
                                   constants.INSTANCE_REBOOT_FULL))
    self._ExpandAndLockInstance()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = {
      "IGNORE_SECONDARIES": self.op.ignore_secondaries,
      "REBOOT_TYPE": self.op.reboot_type,
      "SHUTDOWN_TIMEOUT": self.shutdown_timeout,
      }
    env.update(_BuildInstanceHookEnvByObject(self, self.instance))
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

    _CheckNodeOnline(self, instance.primary_node)

    # check bridges existence
    _CheckInstanceBridgesExist(self, instance)

  def Exec(self, feedback_fn):
    """Reboot the instance.

    """
    instance = self.instance
    ignore_secondaries = self.op.ignore_secondaries
    reboot_type = self.op.reboot_type

    node_current = instance.primary_node

    if reboot_type in [constants.INSTANCE_REBOOT_SOFT,
                       constants.INSTANCE_REBOOT_HARD]:
      for disk in instance.disks:
        self.cfg.SetDiskID(disk, node_current)
      result = self.rpc.call_instance_reboot(node_current, instance,
                                             reboot_type,
                                             self.shutdown_timeout)
      result.Raise("Could not reboot instance")
    else:
      result = self.rpc.call_instance_shutdown(node_current, instance,
                                               self.shutdown_timeout)
      result.Raise("Could not shutdown instance for full reboot")
      _ShutdownInstanceDisks(self, instance)
      _StartInstanceDisks(self, instance, ignore_secondaries)
      result = self.rpc.call_instance_start(node_current, instance, None, None)
      msg = result.fail_msg
      if msg:
        _ShutdownInstanceDisks(self, instance)
        raise errors.OpExecError("Could not start instance for"
                                 " full reboot: %s" % msg)

    self.cfg.MarkInstanceUp(instance.name)


class LUShutdownInstance(LogicalUnit):
  """Shutdown an instance.

  """
  HPATH = "instance-stop"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    self.timeout = getattr(self.op, "timeout",
                           constants.DEFAULT_SHUTDOWN_TIMEOUT)

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = _BuildInstanceHookEnvByObject(self, self.instance)
    env["TIMEOUT"] = self.timeout
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, self.instance.primary_node)

  def Exec(self, feedback_fn):
    """Shutdown the instance.

    """
    instance = self.instance
    node_current = instance.primary_node
    timeout = self.timeout
    self.cfg.MarkInstanceDown(instance.name)
    result = self.rpc.call_instance_shutdown(node_current, instance, timeout)
    msg = result.fail_msg
    if msg:
      self.proc.LogWarning("Could not shutdown instance: %s" % msg)

    _ShutdownInstanceDisks(self, instance)


class LUReinstallInstance(LogicalUnit):
  """Reinstall an instance.

  """
  HPATH = "instance-reinstall"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = _BuildInstanceHookEnvByObject(self, self.instance)
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster and is not running.

    """
    instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, instance.primary_node)

    if instance.disk_template == constants.DT_DISKLESS:
      raise errors.OpPrereqError("Instance '%s' has no disks" %
                                 self.op.instance_name,
                                 errors.ECODE_INVAL)
    _CheckInstanceDown(self, instance, "cannot reinstall")

    self.op.os_type = getattr(self.op, "os_type", None)
    self.op.force_variant = getattr(self.op, "force_variant", False)
    if self.op.os_type is not None:
      # OS verification
      pnode = _ExpandNodeName(self.cfg, instance.primary_node)
      _CheckNodeHasOS(self, pnode, self.op.os_type, self.op.force_variant)

    self.instance = instance

  def Exec(self, feedback_fn):
    """Reinstall the instance.

    """
    inst = self.instance

    if self.op.os_type is not None:
      feedback_fn("Changing OS to '%s'..." % self.op.os_type)
      inst.os = self.op.os_type
      self.cfg.Update(inst, feedback_fn)

    _StartInstanceDisks(self, inst, None)
    try:
      feedback_fn("Running the instance OS create scripts...")
      # FIXME: pass debug option from opcode to backend
      result = self.rpc.call_instance_os_add(inst.primary_node, inst, True,
                                             self.op.debug_level)
      result.Raise("Could not install OS for instance %s on node %s" %
                   (inst.name, inst.primary_node))
    finally:
      _ShutdownInstanceDisks(self, inst)


class LURecreateInstanceDisks(LogicalUnit):
  """Recreate an instance's missing disks.

  """
  HPATH = "instance-recreate-disks"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "disks"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    if not isinstance(self.op.disks, list):
      raise errors.OpPrereqError("Invalid disks parameter", errors.ECODE_INVAL)
    for item in self.op.disks:
      if (not isinstance(item, int) or
          item < 0):
        raise errors.OpPrereqError("Invalid disk specification '%s'" %
                                   str(item), errors.ECODE_INVAL)

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = _BuildInstanceHookEnvByObject(self, self.instance)
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster and is not running.

    """
    instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, instance.primary_node)

    if instance.disk_template == constants.DT_DISKLESS:
      raise errors.OpPrereqError("Instance '%s' has no disks" %
                                 self.op.instance_name, errors.ECODE_INVAL)
    _CheckInstanceDown(self, instance, "cannot recreate disks")

    if not self.op.disks:
      self.op.disks = range(len(instance.disks))
    else:
      for idx in self.op.disks:
        if idx >= len(instance.disks):
          raise errors.OpPrereqError("Invalid disk index passed '%s'" % idx,
                                     errors.ECODE_INVAL)

    self.instance = instance

  def Exec(self, feedback_fn):
    """Recreate the disks.

    """
    to_skip = []
    for idx, _ in enumerate(self.instance.disks):
      if idx not in self.op.disks: # disk idx has not been passed in
        to_skip.append(idx)
        continue

    _CreateDisks(self, self.instance, to_skip=to_skip)


class LURenameInstance(LogicalUnit):
  """Rename an instance.

  """
  HPATH = "instance-rename"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "new_name"]

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = _BuildInstanceHookEnvByObject(self, self.instance)
    env["INSTANCE_NEW_NAME"] = self.op.new_name
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster and is not running.

    """
    self.op.instance_name = _ExpandInstanceName(self.cfg,
                                                self.op.instance_name)
    instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert instance is not None
    _CheckNodeOnline(self, instance.primary_node)
    _CheckInstanceDown(self, instance, "cannot rename")
    self.instance = instance

    # new name verification
    name_info = utils.GetHostInfo(self.op.new_name)

    self.op.new_name = new_name = name_info.name
    instance_list = self.cfg.GetInstanceList()
    if new_name in instance_list:
      raise errors.OpPrereqError("Instance '%s' is already in the cluster" %
                                 new_name, errors.ECODE_EXISTS)

    if not getattr(self.op, "ignore_ip", False):
      if utils.TcpPing(name_info.ip, constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("IP %s of instance %s already in use" %
                                   (name_info.ip, new_name),
                                   errors.ECODE_NOTUNIQUE)


  def Exec(self, feedback_fn):
    """Reinstall the instance.

    """
    inst = self.instance
    old_name = inst.name

    if inst.disk_template == constants.DT_FILE:
      old_file_storage_dir = os.path.dirname(inst.disks[0].logical_id[1])

    self.cfg.RenameInstance(inst.name, self.op.new_name)
    # Change the instance lock. This is definitely safe while we hold the BGL
    self.context.glm.remove(locking.LEVEL_INSTANCE, old_name)
    self.context.glm.add(locking.LEVEL_INSTANCE, self.op.new_name)

    # re-read the instance from the configuration after rename
    inst = self.cfg.GetInstanceInfo(self.op.new_name)

    if inst.disk_template == constants.DT_FILE:
      new_file_storage_dir = os.path.dirname(inst.disks[0].logical_id[1])
      result = self.rpc.call_file_storage_dir_rename(inst.primary_node,
                                                     old_file_storage_dir,
                                                     new_file_storage_dir)
      result.Raise("Could not rename on node %s directory '%s' to '%s'"
                   " (but the instance has been renamed in Ganeti)" %
                   (inst.primary_node, old_file_storage_dir,
                    new_file_storage_dir))

    _StartInstanceDisks(self, inst, None)
    try:
      result = self.rpc.call_instance_run_rename(inst.primary_node, inst,
                                                 old_name, self.op.debug_level)
      msg = result.fail_msg
      if msg:
        msg = ("Could not run OS rename script for instance %s on node %s"
               " (but the instance has been renamed in Ganeti): %s" %
               (inst.name, inst.primary_node, msg))
        self.proc.LogWarning(msg)
    finally:
      _ShutdownInstanceDisks(self, inst)


class LURemoveInstance(LogicalUnit):
  """Remove an instance.

  """
  HPATH = "instance-remove"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "ignore_failures"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    self.shutdown_timeout = getattr(self.op, "shutdown_timeout",
                                    constants.DEFAULT_SHUTDOWN_TIMEOUT)

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = _BuildInstanceHookEnvByObject(self, self.instance)
    env["SHUTDOWN_TIMEOUT"] = self.shutdown_timeout
    nl = [self.cfg.GetMasterNode()]
    nl_post = list(self.instance.all_nodes) + nl
    return env, nl, nl_post

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

  def Exec(self, feedback_fn):
    """Remove the instance.

    """
    instance = self.instance
    logging.info("Shutting down instance %s on node %s",
                 instance.name, instance.primary_node)

    result = self.rpc.call_instance_shutdown(instance.primary_node, instance,
                                             self.shutdown_timeout)
    msg = result.fail_msg
    if msg:
      if self.op.ignore_failures:
        feedback_fn("Warning: can't shutdown instance: %s" % msg)
      else:
        raise errors.OpExecError("Could not shutdown instance %s on"
                                 " node %s: %s" %
                                 (instance.name, instance.primary_node, msg))

    _RemoveInstance(self, feedback_fn, instance, self.op.ignore_failures)


def _RemoveInstance(lu, feedback_fn, instance, ignore_failures):
  """Utility function to remove an instance.

  """
  logging.info("Removing block devices for instance %s", instance.name)

  if not _RemoveDisks(lu, instance):
    if not ignore_failures:
      raise errors.OpExecError("Can't remove instance's disks")
    feedback_fn("Warning: can't remove instance's disks")

  logging.info("Removing instance %s out of cluster config", instance.name)

  lu.cfg.RemoveInstance(instance.name)

  assert not lu.remove_locks.get(locking.LEVEL_INSTANCE), \
    "Instance lock removal conflict"

  # Remove lock for the instance
  lu.remove_locks[locking.LEVEL_INSTANCE] = instance.name


class LUQueryInstances(NoHooksLU):
  """Logical unit for querying instances.

  """
  # pylint: disable-msg=W0142
  _OP_REQP = ["output_fields", "names", "use_locking"]
  REQ_BGL = False
  _SIMPLE_FIELDS = ["name", "os", "network_port", "hypervisor",
                    "serial_no", "ctime", "mtime", "uuid"]
  _FIELDS_STATIC = utils.FieldSet(*["name", "os", "pnode", "snodes",
                                    "admin_state",
                                    "disk_template", "ip", "mac", "bridge",
                                    "nic_mode", "nic_link",
                                    "sda_size", "sdb_size", "vcpus", "tags",
                                    "network_port", "beparams",
                                    r"(disk)\.(size)/([0-9]+)",
                                    r"(disk)\.(sizes)", "disk_usage",
                                    r"(nic)\.(mac|ip|mode|link)/([0-9]+)",
                                    r"(nic)\.(bridge)/([0-9]+)",
                                    r"(nic)\.(macs|ips|modes|links|bridges)",
                                    r"(disk|nic)\.(count)",
                                    "hvparams",
                                    ] + _SIMPLE_FIELDS +
                                  ["hv/%s" % name
                                   for name in constants.HVS_PARAMETERS
                                   if name not in constants.HVC_GLOBALS] +
                                  ["be/%s" % name
                                   for name in constants.BES_PARAMETERS])
  _FIELDS_DYNAMIC = utils.FieldSet("oper_state", "oper_ram", "status")


  def ExpandNames(self):
    _CheckOutputFields(static=self._FIELDS_STATIC,
                       dynamic=self._FIELDS_DYNAMIC,
                       selected=self.op.output_fields)

    self.needed_locks = {}
    self.share_locks[locking.LEVEL_INSTANCE] = 1
    self.share_locks[locking.LEVEL_NODE] = 1

    if self.op.names:
      self.wanted = _GetWantedInstances(self, self.op.names)
    else:
      self.wanted = locking.ALL_SET

    self.do_node_query = self._FIELDS_STATIC.NonMatching(self.op.output_fields)
    self.do_locking = self.do_node_query and self.op.use_locking
    if self.do_locking:
      self.needed_locks[locking.LEVEL_INSTANCE] = self.wanted
      self.needed_locks[locking.LEVEL_NODE] = []
      self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE and self.do_locking:
      self._LockInstancesNodes()

  def CheckPrereq(self):
    """Check prerequisites.

    """
    pass

  def Exec(self, feedback_fn):
    """Computes the list of nodes and their attributes.

    """
    # pylint: disable-msg=R0912
    # way too many branches here
    all_info = self.cfg.GetAllInstancesInfo()
    if self.wanted == locking.ALL_SET:
      # caller didn't specify instance names, so ordering is not important
      if self.do_locking:
        instance_names = self.acquired_locks[locking.LEVEL_INSTANCE]
      else:
        instance_names = all_info.keys()
      instance_names = utils.NiceSort(instance_names)
    else:
      # caller did specify names, so we must keep the ordering
      if self.do_locking:
        tgt_set = self.acquired_locks[locking.LEVEL_INSTANCE]
      else:
        tgt_set = all_info.keys()
      missing = set(self.wanted).difference(tgt_set)
      if missing:
        raise errors.OpExecError("Some instances were removed before"
                                 " retrieving their data: %s" % missing)
      instance_names = self.wanted

    instance_list = [all_info[iname] for iname in instance_names]

    # begin data gathering

    nodes = frozenset([inst.primary_node for inst in instance_list])
    hv_list = list(set([inst.hypervisor for inst in instance_list]))

    bad_nodes = []
    off_nodes = []
    if self.do_node_query:
      live_data = {}
      node_data = self.rpc.call_all_instances_info(nodes, hv_list)
      for name in nodes:
        result = node_data[name]
        if result.offline:
          # offline nodes will be in both lists
          off_nodes.append(name)
        if result.fail_msg:
          bad_nodes.append(name)
        else:
          if result.payload:
            live_data.update(result.payload)
          # else no instance is alive
    else:
      live_data = dict([(name, {}) for name in instance_names])

    # end data gathering

    HVPREFIX = "hv/"
    BEPREFIX = "be/"
    output = []
    cluster = self.cfg.GetClusterInfo()
    for instance in instance_list:
      iout = []
      i_hv = cluster.FillHV(instance, skip_globals=True)
      i_be = cluster.FillBE(instance)
      i_nicp = [cluster.SimpleFillNIC(nic.nicparams) for nic in instance.nics]
      for field in self.op.output_fields:
        st_match = self._FIELDS_STATIC.Matches(field)
        if field in self._SIMPLE_FIELDS:
          val = getattr(instance, field)
        elif field == "pnode":
          val = instance.primary_node
        elif field == "snodes":
          val = list(instance.secondary_nodes)
        elif field == "admin_state":
          val = instance.admin_up
        elif field == "oper_state":
          if instance.primary_node in bad_nodes:
            val = None
          else:
            val = bool(live_data.get(instance.name))
        elif field == "status":
          if instance.primary_node in off_nodes:
            val = "ERROR_nodeoffline"
          elif instance.primary_node in bad_nodes:
            val = "ERROR_nodedown"
          else:
            running = bool(live_data.get(instance.name))
            if running:
              if instance.admin_up:
                val = "running"
              else:
                val = "ERROR_up"
            else:
              if instance.admin_up:
                val = "ERROR_down"
              else:
                val = "ADMIN_down"
        elif field == "oper_ram":
          if instance.primary_node in bad_nodes:
            val = None
          elif instance.name in live_data:
            val = live_data[instance.name].get("memory", "?")
          else:
            val = "-"
        elif field == "vcpus":
          val = i_be[constants.BE_VCPUS]
        elif field == "disk_template":
          val = instance.disk_template
        elif field == "ip":
          if instance.nics:
            val = instance.nics[0].ip
          else:
            val = None
        elif field == "nic_mode":
          if instance.nics:
            val = i_nicp[0][constants.NIC_MODE]
          else:
            val = None
        elif field == "nic_link":
          if instance.nics:
            val = i_nicp[0][constants.NIC_LINK]
          else:
            val = None
        elif field == "bridge":
          if (instance.nics and
              i_nicp[0][constants.NIC_MODE] == constants.NIC_MODE_BRIDGED):
            val = i_nicp[0][constants.NIC_LINK]
          else:
            val = None
        elif field == "mac":
          if instance.nics:
            val = instance.nics[0].mac
          else:
            val = None
        elif field == "sda_size" or field == "sdb_size":
          idx = ord(field[2]) - ord('a')
          try:
            val = instance.FindDisk(idx).size
          except errors.OpPrereqError:
            val = None
        elif field == "disk_usage": # total disk usage per node
          disk_sizes = [{'size': disk.size} for disk in instance.disks]
          val = _ComputeDiskSize(instance.disk_template, disk_sizes)
        elif field == "tags":
          val = list(instance.GetTags())
        elif field == "hvparams":
          val = i_hv
        elif (field.startswith(HVPREFIX) and
              field[len(HVPREFIX):] in constants.HVS_PARAMETERS and
              field[len(HVPREFIX):] not in constants.HVC_GLOBALS):
          val = i_hv.get(field[len(HVPREFIX):], None)
        elif field == "beparams":
          val = i_be
        elif (field.startswith(BEPREFIX) and
              field[len(BEPREFIX):] in constants.BES_PARAMETERS):
          val = i_be.get(field[len(BEPREFIX):], None)
        elif st_match and st_match.groups():
          # matches a variable list
          st_groups = st_match.groups()
          if st_groups and st_groups[0] == "disk":
            if st_groups[1] == "count":
              val = len(instance.disks)
            elif st_groups[1] == "sizes":
              val = [disk.size for disk in instance.disks]
            elif st_groups[1] == "size":
              try:
                val = instance.FindDisk(st_groups[2]).size
              except errors.OpPrereqError:
                val = None
            else:
              assert False, "Unhandled disk parameter"
          elif st_groups[0] == "nic":
            if st_groups[1] == "count":
              val = len(instance.nics)
            elif st_groups[1] == "macs":
              val = [nic.mac for nic in instance.nics]
            elif st_groups[1] == "ips":
              val = [nic.ip for nic in instance.nics]
            elif st_groups[1] == "modes":
              val = [nicp[constants.NIC_MODE] for nicp in i_nicp]
            elif st_groups[1] == "links":
              val = [nicp[constants.NIC_LINK] for nicp in i_nicp]
            elif st_groups[1] == "bridges":
              val = []
              for nicp in i_nicp:
                if nicp[constants.NIC_MODE] == constants.NIC_MODE_BRIDGED:
                  val.append(nicp[constants.NIC_LINK])
                else:
                  val.append(None)
            else:
              # index-based item
              nic_idx = int(st_groups[2])
              if nic_idx >= len(instance.nics):
                val = None
              else:
                if st_groups[1] == "mac":
                  val = instance.nics[nic_idx].mac
                elif st_groups[1] == "ip":
                  val = instance.nics[nic_idx].ip
                elif st_groups[1] == "mode":
                  val = i_nicp[nic_idx][constants.NIC_MODE]
                elif st_groups[1] == "link":
                  val = i_nicp[nic_idx][constants.NIC_LINK]
                elif st_groups[1] == "bridge":
                  nic_mode = i_nicp[nic_idx][constants.NIC_MODE]
                  if nic_mode == constants.NIC_MODE_BRIDGED:
                    val = i_nicp[nic_idx][constants.NIC_LINK]
                  else:
                    val = None
                else:
                  assert False, "Unhandled NIC parameter"
          else:
            assert False, ("Declared but unhandled variable parameter '%s'" %
                           field)
        else:
          assert False, "Declared but unhandled parameter '%s'" % field
        iout.append(val)
      output.append(iout)

    return output


class LUFailoverInstance(LogicalUnit):
  """Failover an instance.

  """
  HPATH = "instance-failover"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "ignore_consistency"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    self.shutdown_timeout = getattr(self.op, "shutdown_timeout",
                                    constants.DEFAULT_SHUTDOWN_TIMEOUT)

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    instance = self.instance
    source_node = instance.primary_node
    target_node = instance.secondary_nodes[0]
    env = {
      "IGNORE_CONSISTENCY": self.op.ignore_consistency,
      "SHUTDOWN_TIMEOUT": self.shutdown_timeout,
      "OLD_PRIMARY": source_node,
      "OLD_SECONDARY": target_node,
      "NEW_PRIMARY": target_node,
      "NEW_SECONDARY": source_node,
      }
    env.update(_BuildInstanceHookEnvByObject(self, instance))
    nl = [self.cfg.GetMasterNode()] + list(instance.secondary_nodes)
    nl_post = list(nl)
    nl_post.append(source_node)
    return env, nl, nl_post

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

    bep = self.cfg.GetClusterInfo().FillBE(instance)
    if instance.disk_template not in constants.DTS_NET_MIRROR:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " network mirrored, cannot failover.",
                                 errors.ECODE_STATE)

    secondary_nodes = instance.secondary_nodes
    if not secondary_nodes:
      raise errors.ProgrammerError("no secondary node but using "
                                   "a mirrored disk template")

    target_node = secondary_nodes[0]
    _CheckNodeOnline(self, target_node)
    _CheckNodeNotDrained(self, target_node)
    if instance.admin_up:
      # check memory requirements on the secondary node
      _CheckNodeFreeMemory(self, target_node, "failing over instance %s" %
                           instance.name, bep[constants.BE_MEMORY],
                           instance.hypervisor)
    else:
      self.LogInfo("Not checking memory on the secondary node as"
                   " instance will not be started")

    # check bridge existance
    _CheckInstanceBridgesExist(self, instance, node=target_node)

  def Exec(self, feedback_fn):
    """Failover an instance.

    The failover is done by shutting it down on its present node and
    starting it on the secondary.

    """
    instance = self.instance

    source_node = instance.primary_node
    target_node = instance.secondary_nodes[0]

    if instance.admin_up:
      feedback_fn("* checking disk consistency between source and target")
      for dev in instance.disks:
        # for drbd, these are drbd over lvm
        if not _CheckDiskConsistency(self, dev, target_node, False):
          if not self.op.ignore_consistency:
            raise errors.OpExecError("Disk %s is degraded on target node,"
                                     " aborting failover." % dev.iv_name)
    else:
      feedback_fn("* not checking disk consistency as instance is not running")

    feedback_fn("* shutting down instance on source node")
    logging.info("Shutting down instance %s on node %s",
                 instance.name, source_node)

    result = self.rpc.call_instance_shutdown(source_node, instance,
                                             self.shutdown_timeout)
    msg = result.fail_msg
    if msg:
      if self.op.ignore_consistency:
        self.proc.LogWarning("Could not shutdown instance %s on node %s."
                             " Proceeding anyway. Please make sure node"
                             " %s is down. Error details: %s",
                             instance.name, source_node, source_node, msg)
      else:
        raise errors.OpExecError("Could not shutdown instance %s on"
                                 " node %s: %s" %
                                 (instance.name, source_node, msg))

    feedback_fn("* deactivating the instance's disks on source node")
    if not _ShutdownInstanceDisks(self, instance, ignore_primary=True):
      raise errors.OpExecError("Can't shut down the instance's disks.")

    instance.primary_node = target_node
    # distribute new instance config to the other nodes
    self.cfg.Update(instance, feedback_fn)

    # Only start the instance if it's marked as up
    if instance.admin_up:
      feedback_fn("* activating the instance's disks on target node")
      logging.info("Starting instance %s on node %s",
                   instance.name, target_node)

      disks_ok, _ = _AssembleInstanceDisks(self, instance,
                                               ignore_secondaries=True)
      if not disks_ok:
        _ShutdownInstanceDisks(self, instance)
        raise errors.OpExecError("Can't activate the instance's disks")

      feedback_fn("* starting the instance on the target node")
      result = self.rpc.call_instance_start(target_node, instance, None, None)
      msg = result.fail_msg
      if msg:
        _ShutdownInstanceDisks(self, instance)
        raise errors.OpExecError("Could not start instance %s on node %s: %s" %
                                 (instance.name, target_node, msg))


class LUMigrateInstance(LogicalUnit):
  """Migrate an instance.

  This is migration without shutting down, compared to the failover,
  which is done with shutdown.

  """
  HPATH = "instance-migrate"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "live", "cleanup"]

  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()

    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

    self._migrater = TLMigrateInstance(self, self.op.instance_name,
                                       self.op.live, self.op.cleanup)
    self.tasklets = [self._migrater]

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    instance = self._migrater.instance
    source_node = instance.primary_node
    target_node = instance.secondary_nodes[0]
    env = _BuildInstanceHookEnvByObject(self, instance)
    env["MIGRATE_LIVE"] = self.op.live
    env["MIGRATE_CLEANUP"] = self.op.cleanup
    env.update({
        "OLD_PRIMARY": source_node,
        "OLD_SECONDARY": target_node,
        "NEW_PRIMARY": target_node,
        "NEW_SECONDARY": source_node,
        })
    nl = [self.cfg.GetMasterNode()] + list(instance.secondary_nodes)
    nl_post = list(nl)
    nl_post.append(source_node)
    return env, nl, nl_post


class LUMoveInstance(LogicalUnit):
  """Move an instance by data-copying.

  """
  HPATH = "instance-move"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "target_node"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    self.shutdown_timeout = getattr(self.op, "shutdown_timeout",
                                    constants.DEFAULT_SHUTDOWN_TIMEOUT)

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    target_node = _ExpandNodeName(self.cfg, self.op.target_node)
    self.op.target_node = target_node
    self.needed_locks[locking.LEVEL_NODE] = [target_node]
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_APPEND

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes(primary_only=True)

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = {
      "TARGET_NODE": self.op.target_node,
      "SHUTDOWN_TIMEOUT": self.shutdown_timeout,
      }
    env.update(_BuildInstanceHookEnvByObject(self, self.instance))
    nl = [self.cfg.GetMasterNode()] + [self.instance.primary_node,
                                       self.op.target_node]
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name

    node = self.cfg.GetNodeInfo(self.op.target_node)
    assert node is not None, \
      "Cannot retrieve locked node %s" % self.op.target_node

    self.target_node = target_node = node.name

    if target_node == instance.primary_node:
      raise errors.OpPrereqError("Instance %s is already on the node %s" %
                                 (instance.name, target_node),
                                 errors.ECODE_STATE)

    bep = self.cfg.GetClusterInfo().FillBE(instance)

    for idx, dsk in enumerate(instance.disks):
      if dsk.dev_type not in (constants.LD_LV, constants.LD_FILE):
        raise errors.OpPrereqError("Instance disk %d has a complex layout,"
                                   " cannot copy" % idx, errors.ECODE_STATE)

    _CheckNodeOnline(self, target_node)
    _CheckNodeNotDrained(self, target_node)

    if instance.admin_up:
      # check memory requirements on the secondary node
      _CheckNodeFreeMemory(self, target_node, "failing over instance %s" %
                           instance.name, bep[constants.BE_MEMORY],
                           instance.hypervisor)
    else:
      self.LogInfo("Not checking memory on the secondary node as"
                   " instance will not be started")

    # check bridge existance
    _CheckInstanceBridgesExist(self, instance, node=target_node)

  def Exec(self, feedback_fn):
    """Move an instance.

    The move is done by shutting it down on its present node, copying
    the data over (slow) and starting it on the new node.

    """
    instance = self.instance

    source_node = instance.primary_node
    target_node = self.target_node

    self.LogInfo("Shutting down instance %s on source node %s",
                 instance.name, source_node)

    result = self.rpc.call_instance_shutdown(source_node, instance,
                                             self.shutdown_timeout)
    msg = result.fail_msg
    if msg:
      if self.op.ignore_consistency:
        self.proc.LogWarning("Could not shutdown instance %s on node %s."
                             " Proceeding anyway. Please make sure node"
                             " %s is down. Error details: %s",
                             instance.name, source_node, source_node, msg)
      else:
        raise errors.OpExecError("Could not shutdown instance %s on"
                                 " node %s: %s" %
                                 (instance.name, source_node, msg))

    # create the target disks
    try:
      _CreateDisks(self, instance, target_node=target_node)
    except errors.OpExecError:
      self.LogWarning("Device creation failed, reverting...")
      try:
        _RemoveDisks(self, instance, target_node=target_node)
      finally:
        self.cfg.ReleaseDRBDMinors(instance.name)
        raise

    cluster_name = self.cfg.GetClusterInfo().cluster_name

    errs = []
    # activate, get path, copy the data over
    for idx, disk in enumerate(instance.disks):
      self.LogInfo("Copying data for disk %d", idx)
      result = self.rpc.call_blockdev_assemble(target_node, disk,
                                               instance.name, True)
      if result.fail_msg:
        self.LogWarning("Can't assemble newly created disk %d: %s",
                        idx, result.fail_msg)
        errs.append(result.fail_msg)
        break
      dev_path = result.payload
      result = self.rpc.call_blockdev_export(source_node, disk,
                                             target_node, dev_path,
                                             cluster_name)
      if result.fail_msg:
        self.LogWarning("Can't copy data over for disk %d: %s",
                        idx, result.fail_msg)
        errs.append(result.fail_msg)
        break

    if errs:
      self.LogWarning("Some disks failed to copy, aborting")
      try:
        _RemoveDisks(self, instance, target_node=target_node)
      finally:
        self.cfg.ReleaseDRBDMinors(instance.name)
        raise errors.OpExecError("Errors during disk copy: %s" %
                                 (",".join(errs),))

    instance.primary_node = target_node
    self.cfg.Update(instance, feedback_fn)

    self.LogInfo("Removing the disks on the original node")
    _RemoveDisks(self, instance, target_node=source_node)

    # Only start the instance if it's marked as up
    if instance.admin_up:
      self.LogInfo("Starting instance %s on node %s",
                   instance.name, target_node)

      disks_ok, _ = _AssembleInstanceDisks(self, instance,
                                           ignore_secondaries=True)
      if not disks_ok:
        _ShutdownInstanceDisks(self, instance)
        raise errors.OpExecError("Can't activate the instance's disks")

      result = self.rpc.call_instance_start(target_node, instance, None, None)
      msg = result.fail_msg
      if msg:
        _ShutdownInstanceDisks(self, instance)
        raise errors.OpExecError("Could not start instance %s on node %s: %s" %
                                 (instance.name, target_node, msg))


class LUMigrateNode(LogicalUnit):
  """Migrate all instances from a node.

  """
  HPATH = "node-migrate"
  HTYPE = constants.HTYPE_NODE
  _OP_REQP = ["node_name", "live"]
  REQ_BGL = False

  def ExpandNames(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)

    self.needed_locks = {
      locking.LEVEL_NODE: [self.op.node_name],
      }

    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_APPEND

    # Create tasklets for migrating instances for all instances on this node
    names = []
    tasklets = []

    for inst in _GetNodePrimaryInstances(self.cfg, self.op.node_name):
      logging.debug("Migrating instance %s", inst.name)
      names.append(inst.name)

      tasklets.append(TLMigrateInstance(self, inst.name, self.op.live, False))

    self.tasklets = tasklets

    # Declare instance locks
    self.needed_locks[locking.LEVEL_INSTANCE] = names

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "NODE_NAME": self.op.node_name,
      }

    nl = [self.cfg.GetMasterNode()]

    return (env, nl, nl)


class TLMigrateInstance(Tasklet):
  def __init__(self, lu, instance_name, live, cleanup):
    """Initializes this class.

    """
    Tasklet.__init__(self, lu)

    # Parameters
    self.instance_name = instance_name
    self.live = live
    self.cleanup = cleanup

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    instance_name = _ExpandInstanceName(self.lu.cfg, self.instance_name)
    instance = self.cfg.GetInstanceInfo(instance_name)
    assert instance is not None

    if instance.disk_template != constants.DT_DRBD8:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " drbd8, cannot migrate.", errors.ECODE_STATE)

    secondary_nodes = instance.secondary_nodes
    if not secondary_nodes:
      raise errors.ConfigurationError("No secondary node but using"
                                      " drbd8 disk template")

    i_be = self.cfg.GetClusterInfo().FillBE(instance)

    target_node = secondary_nodes[0]
    # check memory requirements on the secondary node
    _CheckNodeFreeMemory(self.lu, target_node, "migrating instance %s" %
                         instance.name, i_be[constants.BE_MEMORY],
                         instance.hypervisor)

    # check bridge existance
    _CheckInstanceBridgesExist(self.lu, instance, node=target_node)

    if not self.cleanup:
      _CheckNodeNotDrained(self.lu, target_node)
      result = self.rpc.call_instance_migratable(instance.primary_node,
                                                 instance)
      result.Raise("Can't migrate, please use failover",
                   prereq=True, ecode=errors.ECODE_STATE)

    self.instance = instance

  def _WaitUntilSync(self):
    """Poll with custom rpc for disk sync.

    This uses our own step-based rpc call.

    """
    self.feedback_fn("* wait until resync is done")
    all_done = False
    while not all_done:
      all_done = True
      result = self.rpc.call_drbd_wait_sync(self.all_nodes,
                                            self.nodes_ip,
                                            self.instance.disks)
      min_percent = 100
      for node, nres in result.items():
        nres.Raise("Cannot resync disks on node %s" % node)
        node_done, node_percent = nres.payload
        all_done = all_done and node_done
        if node_percent is not None:
          min_percent = min(min_percent, node_percent)
      if not all_done:
        if min_percent < 100:
          self.feedback_fn("   - progress: %.1f%%" % min_percent)
        time.sleep(2)

  def _EnsureSecondary(self, node):
    """Demote a node to secondary.

    """
    self.feedback_fn("* switching node %s to secondary mode" % node)

    for dev in self.instance.disks:
      self.cfg.SetDiskID(dev, node)

    result = self.rpc.call_blockdev_close(node, self.instance.name,
                                          self.instance.disks)
    result.Raise("Cannot change disk to secondary on node %s" % node)

  def _GoStandalone(self):
    """Disconnect from the network.

    """
    self.feedback_fn("* changing into standalone mode")
    result = self.rpc.call_drbd_disconnect_net(self.all_nodes, self.nodes_ip,
                                               self.instance.disks)
    for node, nres in result.items():
      nres.Raise("Cannot disconnect disks node %s" % node)

  def _GoReconnect(self, multimaster):
    """Reconnect to the network.

    """
    if multimaster:
      msg = "dual-master"
    else:
      msg = "single-master"
    self.feedback_fn("* changing disks into %s mode" % msg)
    result = self.rpc.call_drbd_attach_net(self.all_nodes, self.nodes_ip,
                                           self.instance.disks,
                                           self.instance.name, multimaster)
    for node, nres in result.items():
      nres.Raise("Cannot change disks config on node %s" % node)

  def _ExecCleanup(self):
    """Try to cleanup after a failed migration.

    The cleanup is done by:
      - check that the instance is running only on one node
        (and update the config if needed)
      - change disks on its secondary node to secondary
      - wait until disks are fully synchronized
      - disconnect from the network
      - change disks into single-master mode
      - wait again until disks are fully synchronized

    """
    instance = self.instance
    target_node = self.target_node
    source_node = self.source_node

    # check running on only one node
    self.feedback_fn("* checking where the instance actually runs"
                     " (if this hangs, the hypervisor might be in"
                     " a bad state)")
    ins_l = self.rpc.call_instance_list(self.all_nodes, [instance.hypervisor])
    for node, result in ins_l.items():
      result.Raise("Can't contact node %s" % node)

    runningon_source = instance.name in ins_l[source_node].payload
    runningon_target = instance.name in ins_l[target_node].payload

    if runningon_source and runningon_target:
      raise errors.OpExecError("Instance seems to be running on two nodes,"
                               " or the hypervisor is confused. You will have"
                               " to ensure manually that it runs only on one"
                               " and restart this operation.")

    if not (runningon_source or runningon_target):
      raise errors.OpExecError("Instance does not seem to be running at all."
                               " In this case, it's safer to repair by"
                               " running 'gnt-instance stop' to ensure disk"
                               " shutdown, and then restarting it.")

    if runningon_target:
      # the migration has actually succeeded, we need to update the config
      self.feedback_fn("* instance running on secondary node (%s),"
                       " updating config" % target_node)
      instance.primary_node = target_node
      self.cfg.Update(instance, self.feedback_fn)
      demoted_node = source_node
    else:
      self.feedback_fn("* instance confirmed to be running on its"
                       " primary node (%s)" % source_node)
      demoted_node = target_node

    self._EnsureSecondary(demoted_node)
    try:
      self._WaitUntilSync()
    except errors.OpExecError:
      # we ignore here errors, since if the device is standalone, it
      # won't be able to sync
      pass
    self._GoStandalone()
    self._GoReconnect(False)
    self._WaitUntilSync()

    self.feedback_fn("* done")

  def _RevertDiskStatus(self):
    """Try to revert the disk status after a failed migration.

    """
    target_node = self.target_node
    try:
      self._EnsureSecondary(target_node)
      self._GoStandalone()
      self._GoReconnect(False)
      self._WaitUntilSync()
    except errors.OpExecError, err:
      self.lu.LogWarning("Migration failed and I can't reconnect the"
                         " drives: error '%s'\n"
                         "Please look and recover the instance status" %
                         str(err))

  def _AbortMigration(self):
    """Call the hypervisor code to abort a started migration.

    """
    instance = self.instance
    target_node = self.target_node
    migration_info = self.migration_info

    abort_result = self.rpc.call_finalize_migration(target_node,
                                                    instance,
                                                    migration_info,
                                                    False)
    abort_msg = abort_result.fail_msg
    if abort_msg:
      logging.error("Aborting migration failed on target node %s: %s",
                    target_node, abort_msg)
      # Don't raise an exception here, as we stil have to try to revert the
      # disk status, even if this step failed.

  def _ExecMigration(self):
    """Migrate an instance.

    The migrate is done by:
      - change the disks into dual-master mode
      - wait until disks are fully synchronized again
      - migrate the instance
      - change disks on the new secondary node (the old primary) to secondary
      - wait until disks are fully synchronized
      - change disks into single-master mode

    """
    instance = self.instance
    target_node = self.target_node
    source_node = self.source_node

    self.feedback_fn("* checking disk consistency between source and target")
    for dev in instance.disks:
      if not _CheckDiskConsistency(self.lu, dev, target_node, False):
        raise errors.OpExecError("Disk %s is degraded or not fully"
                                 " synchronized on target node,"
                                 " aborting migrate." % dev.iv_name)

    # First get the migration information from the remote node
    result = self.rpc.call_migration_info(source_node, instance)
    msg = result.fail_msg
    if msg:
      log_err = ("Failed fetching source migration information from %s: %s" %
                 (source_node, msg))
      logging.error(log_err)
      raise errors.OpExecError(log_err)

    self.migration_info = migration_info = result.payload

    # Then switch the disks to master/master mode
    self._EnsureSecondary(target_node)
    self._GoStandalone()
    self._GoReconnect(True)
    self._WaitUntilSync()

    self.feedback_fn("* preparing %s to accept the instance" % target_node)
    result = self.rpc.call_accept_instance(target_node,
                                           instance,
                                           migration_info,
                                           self.nodes_ip[target_node])

    msg = result.fail_msg
    if msg:
      logging.error("Instance pre-migration failed, trying to revert"
                    " disk status: %s", msg)
      self.feedback_fn("Pre-migration failed, aborting")
      self._AbortMigration()
      self._RevertDiskStatus()
      raise errors.OpExecError("Could not pre-migrate instance %s: %s" %
                               (instance.name, msg))

    self.feedback_fn("* migrating instance to %s" % target_node)
    time.sleep(10)
    result = self.rpc.call_instance_migrate(source_node, instance,
                                            self.nodes_ip[target_node],
                                            self.live)
    msg = result.fail_msg
    if msg:
      logging.error("Instance migration failed, trying to revert"
                    " disk status: %s", msg)
      self.feedback_fn("Migration failed, aborting")
      self._AbortMigration()
      self._RevertDiskStatus()
      raise errors.OpExecError("Could not migrate instance %s: %s" %
                               (instance.name, msg))
    time.sleep(10)

    instance.primary_node = target_node
    # distribute new instance config to the other nodes
    self.cfg.Update(instance, self.feedback_fn)

    result = self.rpc.call_finalize_migration(target_node,
                                              instance,
                                              migration_info,
                                              True)
    msg = result.fail_msg
    if msg:
      logging.error("Instance migration succeeded, but finalization failed:"
                    " %s", msg)
      raise errors.OpExecError("Could not finalize instance migration: %s" %
                               msg)

    self._EnsureSecondary(source_node)
    self._WaitUntilSync()
    self._GoStandalone()
    self._GoReconnect(False)
    self._WaitUntilSync()

    self.feedback_fn("* done")

  def Exec(self, feedback_fn):
    """Perform the migration.

    """
    feedback_fn("Migrating instance %s" % self.instance.name)

    self.feedback_fn = feedback_fn

    self.source_node = self.instance.primary_node
    self.target_node = self.instance.secondary_nodes[0]
    self.all_nodes = [self.source_node, self.target_node]
    self.nodes_ip = {
      self.source_node: self.cfg.GetNodeInfo(self.source_node).secondary_ip,
      self.target_node: self.cfg.GetNodeInfo(self.target_node).secondary_ip,
      }

    if self.cleanup:
      return self._ExecCleanup()
    else:
      return self._ExecMigration()


def _CreateBlockDev(lu, node, instance, device, force_create,
                    info, force_open):
  """Create a tree of block devices on a given node.

  If this device type has to be created on secondaries, create it and
  all its children.

  If not, just recurse to children keeping the same 'force' value.

  @param lu: the lu on whose behalf we execute
  @param node: the node on which to create the device
  @type instance: L{objects.Instance}
  @param instance: the instance which owns the device
  @type device: L{objects.Disk}
  @param device: the device to create
  @type force_create: boolean
  @param force_create: whether to force creation of this device; this
      will be change to True whenever we find a device which has
      CreateOnSecondary() attribute
  @param info: the extra 'metadata' we should attach to the device
      (this will be represented as a LVM tag)
  @type force_open: boolean
  @param force_open: this parameter will be passes to the
      L{backend.BlockdevCreate} function where it specifies
      whether we run on primary or not, and it affects both
      the child assembly and the device own Open() execution

  """
  if device.CreateOnSecondary():
    force_create = True

  if device.children:
    for child in device.children:
      _CreateBlockDev(lu, node, instance, child, force_create,
                      info, force_open)

  if not force_create:
    return

  _CreateSingleBlockDev(lu, node, instance, device, info, force_open)


def _CreateSingleBlockDev(lu, node, instance, device, info, force_open):
  """Create a single block device on a given node.

  This will not recurse over children of the device, so they must be
  created in advance.

  @param lu: the lu on whose behalf we execute
  @param node: the node on which to create the device
  @type instance: L{objects.Instance}
  @param instance: the instance which owns the device
  @type device: L{objects.Disk}
  @param device: the device to create
  @param info: the extra 'metadata' we should attach to the device
      (this will be represented as a LVM tag)
  @type force_open: boolean
  @param force_open: this parameter will be passes to the
      L{backend.BlockdevCreate} function where it specifies
      whether we run on primary or not, and it affects both
      the child assembly and the device own Open() execution

  """
  lu.cfg.SetDiskID(device, node)
  result = lu.rpc.call_blockdev_create(node, device, device.size,
                                       instance.name, force_open, info)
  result.Raise("Can't create block device %s on"
               " node %s for instance %s" % (device, node, instance.name))
  if device.physical_id is None:
    device.physical_id = result.payload


def _GenerateUniqueNames(lu, exts):
  """Generate a suitable LV name.

  This will generate a logical volume name for the given instance.

  """
  results = []
  for val in exts:
    new_id = lu.cfg.GenerateUniqueID(lu.proc.GetECId())
    results.append("%s%s" % (new_id, val))
  return results


def _GenerateDRBD8Branch(lu, primary, secondary, size, names, iv_name,
                         p_minor, s_minor):
  """Generate a drbd8 device complete with its children.

  """
  port = lu.cfg.AllocatePort()
  vgname = lu.cfg.GetVGName()
  shared_secret = lu.cfg.GenerateDRBDSecret(lu.proc.GetECId())
  dev_data = objects.Disk(dev_type=constants.LD_LV, size=size,
                          logical_id=(vgname, names[0]))
  dev_meta = objects.Disk(dev_type=constants.LD_LV, size=128,
                          logical_id=(vgname, names[1]))
  drbd_dev = objects.Disk(dev_type=constants.LD_DRBD8, size=size,
                          logical_id=(primary, secondary, port,
                                      p_minor, s_minor,
                                      shared_secret),
                          children=[dev_data, dev_meta],
                          iv_name=iv_name)
  return drbd_dev


def _GenerateDiskTemplate(lu, template_name,
                          instance_name, primary_node,
                          secondary_nodes, disk_info,
                          file_storage_dir, file_driver,
                          base_index):
  """Generate the entire disk layout for a given template type.

  """
  #TODO: compute space requirements

  vgname = lu.cfg.GetVGName()
  disk_count = len(disk_info)
  disks = []
  if template_name == constants.DT_DISKLESS:
    pass
  elif template_name == constants.DT_PLAIN:
    if len(secondary_nodes) != 0:
      raise errors.ProgrammerError("Wrong template configuration")

    names = _GenerateUniqueNames(lu, [".disk%d" % (base_index + i)
                                      for i in range(disk_count)])
    for idx, disk in enumerate(disk_info):
      disk_index = idx + base_index
      disk_dev = objects.Disk(dev_type=constants.LD_LV, size=disk["size"],
                              logical_id=(vgname, names[idx]),
                              iv_name="disk/%d" % disk_index,
                              mode=disk["mode"])
      disks.append(disk_dev)
  elif template_name == constants.DT_DRBD8:
    if len(secondary_nodes) != 1:
      raise errors.ProgrammerError("Wrong template configuration")
    remote_node = secondary_nodes[0]
    minors = lu.cfg.AllocateDRBDMinor(
      [primary_node, remote_node] * len(disk_info), instance_name)

    names = []
    for lv_prefix in _GenerateUniqueNames(lu, [".disk%d" % (base_index + i)
                                               for i in range(disk_count)]):
      names.append(lv_prefix + "_data")
      names.append(lv_prefix + "_meta")
    for idx, disk in enumerate(disk_info):
      disk_index = idx + base_index
      disk_dev = _GenerateDRBD8Branch(lu, primary_node, remote_node,
                                      disk["size"], names[idx*2:idx*2+2],
                                      "disk/%d" % disk_index,
                                      minors[idx*2], minors[idx*2+1])
      disk_dev.mode = disk["mode"]
      disks.append(disk_dev)
  elif template_name == constants.DT_FILE:
    if len(secondary_nodes) != 0:
      raise errors.ProgrammerError("Wrong template configuration")

    _RequireFileStorage()

    for idx, disk in enumerate(disk_info):
      disk_index = idx + base_index
      disk_dev = objects.Disk(dev_type=constants.LD_FILE, size=disk["size"],
                              iv_name="disk/%d" % disk_index,
                              logical_id=(file_driver,
                                          "%s/disk%d" % (file_storage_dir,
                                                         disk_index)),
                              mode=disk["mode"])
      disks.append(disk_dev)
  else:
    raise errors.ProgrammerError("Invalid disk template '%s'" % template_name)
  return disks


def _GetInstanceInfoText(instance):
  """Compute that text that should be added to the disk's metadata.

  """
  return "originstname+%s" % instance.name


def _CreateDisks(lu, instance, to_skip=None, target_node=None):
  """Create all disks for an instance.

  This abstracts away some work from AddInstance.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type instance: L{objects.Instance}
  @param instance: the instance whose disks we should create
  @type to_skip: list
  @param to_skip: list of indices to skip
  @type target_node: string
  @param target_node: if passed, overrides the target node for creation
  @rtype: boolean
  @return: the success of the creation

  """
  info = _GetInstanceInfoText(instance)
  if target_node is None:
    pnode = instance.primary_node
    all_nodes = instance.all_nodes
  else:
    pnode = target_node
    all_nodes = [pnode]

  if instance.disk_template == constants.DT_FILE:
    file_storage_dir = os.path.dirname(instance.disks[0].logical_id[1])
    result = lu.rpc.call_file_storage_dir_create(pnode, file_storage_dir)

    result.Raise("Failed to create directory '%s' on"
                 " node %s" % (file_storage_dir, pnode))

  # Note: this needs to be kept in sync with adding of disks in
  # LUSetInstanceParams
  for idx, device in enumerate(instance.disks):
    if to_skip and idx in to_skip:
      continue
    logging.info("Creating volume %s for instance %s",
                 device.iv_name, instance.name)
    #HARDCODE
    for node in all_nodes:
      f_create = node == pnode
      _CreateBlockDev(lu, node, instance, device, f_create, info, f_create)


def _RemoveDisks(lu, instance, target_node=None):
  """Remove all disks for an instance.

  This abstracts away some work from `AddInstance()` and
  `RemoveInstance()`. Note that in case some of the devices couldn't
  be removed, the removal will continue with the other ones (compare
  with `_CreateDisks()`).

  @type lu: L{LogicalUnit}
  @param lu: the logical unit on whose behalf we execute
  @type instance: L{objects.Instance}
  @param instance: the instance whose disks we should remove
  @type target_node: string
  @param target_node: used to override the node on which to remove the disks
  @rtype: boolean
  @return: the success of the removal

  """
  logging.info("Removing block devices for instance %s", instance.name)

  all_result = True
  for device in instance.disks:
    if target_node:
      edata = [(target_node, device)]
    else:
      edata = device.ComputeNodeTree(instance.primary_node)
    for node, disk in edata:
      lu.cfg.SetDiskID(disk, node)
      msg = lu.rpc.call_blockdev_remove(node, disk).fail_msg
      if msg:
        lu.LogWarning("Could not remove block device %s on node %s,"
                      " continuing anyway: %s", device.iv_name, node, msg)
        all_result = False

  if instance.disk_template == constants.DT_FILE:
    file_storage_dir = os.path.dirname(instance.disks[0].logical_id[1])
    if target_node:
      tgt = target_node
    else:
      tgt = instance.primary_node
    result = lu.rpc.call_file_storage_dir_remove(tgt, file_storage_dir)
    if result.fail_msg:
      lu.LogWarning("Could not remove directory '%s' on node %s: %s",
                    file_storage_dir, instance.primary_node, result.fail_msg)
      all_result = False

  return all_result


def _ComputeDiskSize(disk_template, disks):
  """Compute disk size requirements in the volume group

  """
  # Required free disk space as a function of disk and swap space
  req_size_dict = {
    constants.DT_DISKLESS: None,
    constants.DT_PLAIN: sum(d["size"] for d in disks),
    # 128 MB are added for drbd metadata for each disk
    constants.DT_DRBD8: sum(d["size"] + 128 for d in disks),
    constants.DT_FILE: None,
  }

  if disk_template not in req_size_dict:
    raise errors.ProgrammerError("Disk template '%s' size requirement"
                                 " is unknown" %  disk_template)

  return req_size_dict[disk_template]


def _CheckHVParams(lu, nodenames, hvname, hvparams):
  """Hypervisor parameter validation.

  This function abstract the hypervisor parameter validation to be
  used in both instance create and instance modify.

  @type lu: L{LogicalUnit}
  @param lu: the logical unit for which we check
  @type nodenames: list
  @param nodenames: the list of nodes on which we should check
  @type hvname: string
  @param hvname: the name of the hypervisor we should use
  @type hvparams: dict
  @param hvparams: the parameters which we need to check
  @raise errors.OpPrereqError: if the parameters are not valid

  """
  hvinfo = lu.rpc.call_hypervisor_validate_params(nodenames,
                                                  hvname,
                                                  hvparams)
  for node in nodenames:
    info = hvinfo[node]
    if info.offline:
      continue
    info.Raise("Hypervisor parameter validation failed on node %s" % node)


class LUCreateInstance(LogicalUnit):
  """Create an instance.

  """
  HPATH = "instance-add"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "disks",
              "mode", "start",
              "wait_for_sync", "ip_check", "nics",
              "hvparams", "beparams"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check arguments.

    """
    # set optional parameters to none if they don't exist
    for attr in ["pnode", "snode", "iallocator", "hypervisor",
                 "disk_template", "identify_defaults"]:
      if not hasattr(self.op, attr):
        setattr(self.op, attr, None)

    # do not require name_check to ease forward/backward compatibility
    # for tools
    if not hasattr(self.op, "name_check"):
      self.op.name_check = True
    if not hasattr(self.op, "no_install"):
      self.op.no_install = False
    if self.op.no_install and self.op.start:
      self.LogInfo("No-installation mode selected, disabling startup")
      self.op.start = False
    # validate/normalize the instance name
    self.op.instance_name = utils.HostInfo.NormalizeName(self.op.instance_name)
    if self.op.ip_check and not self.op.name_check:
      # TODO: make the ip check more flexible and not depend on the name check
      raise errors.OpPrereqError("Cannot do ip checks without a name check",
                                 errors.ECODE_INVAL)

    # check nics' parameter names
    for nic in self.op.nics:
      utils.ForceDictType(nic, constants.INIC_PARAMS_TYPES)

    # check disks. parameter names and consistent adopt/no-adopt strategy
    has_adopt = has_no_adopt = False
    for disk in self.op.disks:
      utils.ForceDictType(disk, constants.IDISK_PARAMS_TYPES)
      if "adopt" in disk:
        has_adopt = True
      else:
        has_no_adopt = True
    if has_adopt and has_no_adopt:
      raise errors.OpPrereqError("Either all disks are adopted or none is",
                                 errors.ECODE_INVAL)
    if has_adopt:
      if self.op.disk_template != constants.DT_PLAIN:
        raise errors.OpPrereqError("Disk adoption is only supported for the"
                                   " 'plain' disk template",
                                   errors.ECODE_INVAL)
      if self.op.iallocator is not None:
        raise errors.OpPrereqError("Disk adoption not allowed with an"
                                   " iallocator script", errors.ECODE_INVAL)
      if self.op.mode == constants.INSTANCE_IMPORT:
        raise errors.OpPrereqError("Disk adoption not allowed for"
                                   " instance import", errors.ECODE_INVAL)

    self.adopt_disks = has_adopt

    # verify creation mode
    if self.op.mode not in constants.INSTANCE_CREATE_MODES:
      raise errors.OpPrereqError("Invalid instance creation mode '%s'" %
                                 self.op.mode, errors.ECODE_INVAL)

    # instance name verification
    if self.op.name_check:
      self.hostname1 = utils.GetHostInfo(self.op.instance_name)
      self.op.instance_name = self.hostname1.name
      # used in CheckPrereq for ip ping check
      self.check_ip = self.hostname1.ip
    elif self.op.mode == constants.INSTANCE_REMOTE_IMPORT:
      raise errors.OpPrereqError("Remote imports require names to be checked" %
                                 errors.ECODE_INVAL)
    else:
      self.check_ip = None

    # file storage checks
    if (self.op.file_driver and
        not self.op.file_driver in constants.FILE_DRIVER):
      raise errors.OpPrereqError("Invalid file driver name '%s'" %
                                 self.op.file_driver, errors.ECODE_INVAL)

    if self.op.file_storage_dir and os.path.isabs(self.op.file_storage_dir):
      raise errors.OpPrereqError("File storage directory path not absolute",
                                 errors.ECODE_INVAL)

    ### Node/iallocator related checks
    if [self.op.iallocator, self.op.pnode].count(None) != 1:
      raise errors.OpPrereqError("One and only one of iallocator and primary"
                                 " node must be given",
                                 errors.ECODE_INVAL)

    self._cds = _GetClusterDomainSecret()

    if self.op.mode == constants.INSTANCE_IMPORT:
      # On import force_variant must be True, because if we forced it at
      # initial install, our only chance when importing it back is that it
      # works again!
      self.op.force_variant = True

      if self.op.no_install:
        self.LogInfo("No-installation mode has no effect during import")

    elif self.op.mode == constants.INSTANCE_CREATE:
      if getattr(self.op, "os_type", None) is None:
        raise errors.OpPrereqError("No guest OS specified",
                                   errors.ECODE_INVAL)
      self.op.force_variant = getattr(self.op, "force_variant", False)
      if self.op.disk_template is None:
        raise errors.OpPrereqError("No disk template specified",
                                   errors.ECODE_INVAL)

    elif self.op.mode == constants.INSTANCE_REMOTE_IMPORT:
      # Check handshake to ensure both clusters have the same domain secret
      src_handshake = getattr(self.op, "source_handshake", None)
      if not src_handshake:
        raise errors.OpPrereqError("Missing source handshake",
                                   errors.ECODE_INVAL)

      errmsg = masterd.instance.CheckRemoteExportHandshake(self._cds,
                                                           src_handshake)
      if errmsg:
        raise errors.OpPrereqError("Invalid handshake: %s" % errmsg,
                                   errors.ECODE_INVAL)

      # Load and check source CA
      self.source_x509_ca_pem = getattr(self.op, "source_x509_ca", None)
      if not self.source_x509_ca_pem:
        raise errors.OpPrereqError("Missing source X509 CA",
                                   errors.ECODE_INVAL)

      try:
        (cert, _) = utils.LoadSignedX509Certificate(self.source_x509_ca_pem,
                                                    self._cds)
      except OpenSSL.crypto.Error, err:
        raise errors.OpPrereqError("Unable to load source X509 CA (%s)" %
                                   (err, ), errors.ECODE_INVAL)

      (errcode, msg) = utils.VerifyX509Certificate(cert, None, None)
      if errcode is not None:
        raise errors.OpPrereqError("Invalid source X509 CA (%s)" % (msg, ),
                                   errors.ECODE_INVAL)

      self.source_x509_ca = cert

      src_instance_name = getattr(self.op, "source_instance_name", None)
      if not src_instance_name:
        raise errors.OpPrereqError("Missing source instance name",
                                   errors.ECODE_INVAL)

      self.source_instance_name = \
        utils.GetHostInfo(utils.HostInfo.NormalizeName(src_instance_name)).name

    else:
      raise errors.OpPrereqError("Invalid instance creation mode %r" %
                                 self.op.mode, errors.ECODE_INVAL)

  def ExpandNames(self):
    """ExpandNames for CreateInstance.

    Figure out the right locks for instance creation.

    """
    self.needed_locks = {}

    instance_name = self.op.instance_name
    # this is just a preventive check, but someone might still add this
    # instance in the meantime, and creation will fail at lock-add time
    if instance_name in self.cfg.GetInstanceList():
      raise errors.OpPrereqError("Instance '%s' is already in the cluster" %
                                 instance_name, errors.ECODE_EXISTS)

    self.add_locks[locking.LEVEL_INSTANCE] = instance_name

    if self.op.iallocator:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET
    else:
      self.op.pnode = _ExpandNodeName(self.cfg, self.op.pnode)
      nodelist = [self.op.pnode]
      if self.op.snode is not None:
        self.op.snode = _ExpandNodeName(self.cfg, self.op.snode)
        nodelist.append(self.op.snode)
      self.needed_locks[locking.LEVEL_NODE] = nodelist

    # in case of import lock the source node too
    if self.op.mode == constants.INSTANCE_IMPORT:
      src_node = getattr(self.op, "src_node", None)
      src_path = getattr(self.op, "src_path", None)

      if src_path is None:
        self.op.src_path = src_path = self.op.instance_name

      if src_node is None:
        self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET
        self.op.src_node = None
        if os.path.isabs(src_path):
          raise errors.OpPrereqError("Importing an instance from an absolute"
                                     " path requires a source node option.",
                                     errors.ECODE_INVAL)
      else:
        self.op.src_node = src_node = _ExpandNodeName(self.cfg, src_node)
        if self.needed_locks[locking.LEVEL_NODE] is not locking.ALL_SET:
          self.needed_locks[locking.LEVEL_NODE].append(src_node)
        if not os.path.isabs(src_path):
          self.op.src_path = src_path = \
            utils.PathJoin(constants.EXPORT_DIR, src_path)

  def _RunAllocator(self):
    """Run the allocator based on input opcode.

    """
    nics = [n.ToDict() for n in self.nics]
    ial = IAllocator(self.cfg, self.rpc,
                     mode=constants.IALLOCATOR_MODE_ALLOC,
                     name=self.op.instance_name,
                     disk_template=self.op.disk_template,
                     tags=[],
                     os=self.op.os_type,
                     vcpus=self.be_full[constants.BE_VCPUS],
                     mem_size=self.be_full[constants.BE_MEMORY],
                     disks=self.disks,
                     nics=nics,
                     hypervisor=self.op.hypervisor,
                     )

    ial.Run(self.op.iallocator)

    if not ial.success:
      raise errors.OpPrereqError("Can't compute nodes using"
                                 " iallocator '%s': %s" %
                                 (self.op.iallocator, ial.info),
                                 errors.ECODE_NORES)
    if len(ial.result) != ial.required_nodes:
      raise errors.OpPrereqError("iallocator '%s' returned invalid number"
                                 " of nodes (%s), required %s" %
                                 (self.op.iallocator, len(ial.result),
                                  ial.required_nodes), errors.ECODE_FAULT)
    self.op.pnode = ial.result[0]
    self.LogInfo("Selected nodes for instance %s via iallocator %s: %s",
                 self.op.instance_name, self.op.iallocator,
                 utils.CommaJoin(ial.result))
    if ial.required_nodes == 2:
      self.op.snode = ial.result[1]

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on master, primary and secondary nodes of the instance.

    """
    env = {
      "ADD_MODE": self.op.mode,
      }
    if self.op.mode == constants.INSTANCE_IMPORT:
      env["SRC_NODE"] = self.op.src_node
      env["SRC_PATH"] = self.op.src_path
      env["SRC_IMAGES"] = self.src_images

    env.update(_BuildInstanceHookEnv(
      name=self.op.instance_name,
      primary_node=self.op.pnode,
      secondary_nodes=self.secondaries,
      status=self.op.start,
      os_type=self.op.os_type,
      memory=self.be_full[constants.BE_MEMORY],
      vcpus=self.be_full[constants.BE_VCPUS],
      nics=_NICListToTuple(self, self.nics),
      disk_template=self.op.disk_template,
      disks=[(d["size"], d["mode"]) for d in self.disks],
      bep=self.be_full,
      hvp=self.hv_full,
      hypervisor_name=self.op.hypervisor,
    ))

    nl = ([self.cfg.GetMasterNode(), self.op.pnode] +
          self.secondaries)
    return env, nl, nl

  def _ReadExportInfo(self):
    """Reads the export information from disk.

    It will override the opcode source node and path with the actual
    information, if these two were not specified before.

    @return: the export information

    """
    assert self.op.mode == constants.INSTANCE_IMPORT

    src_node = self.op.src_node
    src_path = self.op.src_path

    if src_node is None:
      locked_nodes = self.acquired_locks[locking.LEVEL_NODE]
      exp_list = self.rpc.call_export_list(locked_nodes)
      found = False
      for node in exp_list:
        if exp_list[node].fail_msg:
          continue
        if src_path in exp_list[node].payload:
          found = True
          self.op.src_node = src_node = node
          self.op.src_path = src_path = utils.PathJoin(constants.EXPORT_DIR,
                                                       src_path)
          break
      if not found:
        raise errors.OpPrereqError("No export found for relative path %s" %
                                    src_path, errors.ECODE_INVAL)

    _CheckNodeOnline(self, src_node)
    result = self.rpc.call_export_info(src_node, src_path)
    result.Raise("No export or invalid export found in dir %s" % src_path)

    export_info = objects.SerializableConfigParser.Loads(str(result.payload))
    if not export_info.has_section(constants.INISECT_EXP):
      raise errors.ProgrammerError("Corrupted export config",
                                   errors.ECODE_ENVIRON)

    ei_version = export_info.get(constants.INISECT_EXP, "version")
    if (int(ei_version) != constants.EXPORT_VERSION):
      raise errors.OpPrereqError("Wrong export version %s (wanted %d)" %
                                 (ei_version, constants.EXPORT_VERSION),
                                 errors.ECODE_ENVIRON)
    return export_info

  def _ReadExportParams(self, einfo):
    """Use export parameters as defaults.

    In case the opcode doesn't specify (as in override) some instance
    parameters, then try to use them from the export information, if
    that declares them.

    """
    self.op.os_type = einfo.get(constants.INISECT_EXP, "os")

    if self.op.disk_template is None:
      if einfo.has_option(constants.INISECT_INS, "disk_template"):
        self.op.disk_template = einfo.get(constants.INISECT_INS,
                                          "disk_template")
      else:
        raise errors.OpPrereqError("No disk template specified and the export"
                                   " is missing the disk_template information",
                                   errors.ECODE_INVAL)

    if not self.op.disks:
      if einfo.has_option(constants.INISECT_INS, "disk_count"):
        disks = []
        # TODO: import the disk iv_name too
        for idx in range(einfo.getint(constants.INISECT_INS, "disk_count")):
          disk_sz = einfo.getint(constants.INISECT_INS, "disk%d_size" % idx)
          disks.append({"size": disk_sz})
        self.op.disks = disks
      else:
        raise errors.OpPrereqError("No disk info specified and the export"
                                   " is missing the disk information",
                                   errors.ECODE_INVAL)

    if (not self.op.nics and
        einfo.has_option(constants.INISECT_INS, "nic_count")):
      nics = []
      for idx in range(einfo.getint(constants.INISECT_INS, "nic_count")):
        ndict = {}
        for name in list(constants.NICS_PARAMETERS) + ["ip", "mac"]:
          v = einfo.get(constants.INISECT_INS, "nic%d_%s" % (idx, name))
          ndict[name] = v
        nics.append(ndict)
      self.op.nics = nics

    if (self.op.hypervisor is None and
        einfo.has_option(constants.INISECT_INS, "hypervisor")):
      self.op.hypervisor = einfo.get(constants.INISECT_INS, "hypervisor")
    if einfo.has_section(constants.INISECT_HYP):
      # use the export parameters but do not override the ones
      # specified by the user
      for name, value in einfo.items(constants.INISECT_HYP):
        if name not in self.op.hvparams:
          self.op.hvparams[name] = value

    if einfo.has_section(constants.INISECT_BEP):
      # use the parameters, without overriding
      for name, value in einfo.items(constants.INISECT_BEP):
        if name not in self.op.beparams:
          self.op.beparams[name] = value
    else:
      # try to read the parameters old style, from the main section
      for name in constants.BES_PARAMETERS:
        if (name not in self.op.beparams and
            einfo.has_option(constants.INISECT_INS, name)):
          self.op.beparams[name] = einfo.get(constants.INISECT_INS, name)

  def _RevertToDefaults(self, cluster):
    """Revert the instance parameters to the default values.

    """
    # hvparams
    hv_defs = cluster.SimpleFillHV(self.op.hypervisor, self.op.os_type, {})
    for name in self.op.hvparams.keys():
      if name in hv_defs and hv_defs[name] == self.op.hvparams[name]:
        del self.op.hvparams[name]
    # beparams
    be_defs = cluster.SimpleFillBE({})
    for name in self.op.beparams.keys():
      if name in be_defs and be_defs[name] == self.op.beparams[name]:
        del self.op.beparams[name]
    # nic params
    nic_defs = cluster.SimpleFillNIC({})
    for nic in self.op.nics:
      for name in constants.NICS_PARAMETERS:
        if name in nic and name in nic_defs and nic[name] == nic_defs[name]:
          del nic[name]

  def CheckPrereq(self):
    """Check prerequisites.

    """
    if self.op.mode == constants.INSTANCE_IMPORT:
      export_info = self._ReadExportInfo()
      self._ReadExportParams(export_info)

    _CheckDiskTemplate(self.op.disk_template)

    if (not self.cfg.GetVGName() and
        self.op.disk_template not in constants.DTS_NOT_LVM):
      raise errors.OpPrereqError("Cluster does not support lvm-based"
                                 " instances", errors.ECODE_STATE)

    if self.op.hypervisor is None:
      self.op.hypervisor = self.cfg.GetHypervisorType()

    cluster = self.cfg.GetClusterInfo()
    enabled_hvs = cluster.enabled_hypervisors
    if self.op.hypervisor not in enabled_hvs:
      raise errors.OpPrereqError("Selected hypervisor (%s) not enabled in the"
                                 " cluster (%s)" % (self.op.hypervisor,
                                  ",".join(enabled_hvs)),
                                 errors.ECODE_STATE)

    # check hypervisor parameter syntax (locally)
    utils.ForceDictType(self.op.hvparams, constants.HVS_PARAMETER_TYPES)
    filled_hvp = cluster.SimpleFillHV(self.op.hypervisor, self.op.os_type,
                                      self.op.hvparams)
    hv_type = hypervisor.GetHypervisor(self.op.hypervisor)
    hv_type.CheckParameterSyntax(filled_hvp)
    self.hv_full = filled_hvp
    # check that we don't specify global parameters on an instance
    _CheckGlobalHvParams(self.op.hvparams)

    # fill and remember the beparams dict
    utils.ForceDictType(self.op.beparams, constants.BES_PARAMETER_TYPES)
    self.be_full = cluster.SimpleFillBE(self.op.beparams)

    # now that hvp/bep are in final format, let's reset to defaults,
    # if told to do so
    if self.op.identify_defaults:
      self._RevertToDefaults(cluster)

    # NIC buildup
    self.nics = []
    for idx, nic in enumerate(self.op.nics):
      nic_mode_req = nic.get("mode", None)
      nic_mode = nic_mode_req
      if nic_mode is None:
        nic_mode = cluster.nicparams[constants.PP_DEFAULT][constants.NIC_MODE]

      # in routed mode, for the first nic, the default ip is 'auto'
      if nic_mode == constants.NIC_MODE_ROUTED and idx == 0:
        default_ip_mode = constants.VALUE_AUTO
      else:
        default_ip_mode = constants.VALUE_NONE

      # ip validity checks
      ip = nic.get("ip", default_ip_mode)
      if ip is None or ip.lower() == constants.VALUE_NONE:
        nic_ip = None
      elif ip.lower() == constants.VALUE_AUTO:
        if not self.op.name_check:
          raise errors.OpPrereqError("IP address set to auto but name checks"
                                     " have been skipped. Aborting.",
                                     errors.ECODE_INVAL)
        nic_ip = self.hostname1.ip
      else:
        if not utils.IsValidIP(ip):
          raise errors.OpPrereqError("Given IP address '%s' doesn't look"
                                     " like a valid IP" % ip,
                                     errors.ECODE_INVAL)
        nic_ip = ip

      # TODO: check the ip address for uniqueness
      if nic_mode == constants.NIC_MODE_ROUTED and not nic_ip:
        raise errors.OpPrereqError("Routed nic mode requires an ip address",
                                   errors.ECODE_INVAL)

      # MAC address verification
      mac = nic.get("mac", constants.VALUE_AUTO)
      if mac not in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
        mac = utils.NormalizeAndValidateMac(mac)

        try:
          self.cfg.ReserveMAC(mac, self.proc.GetECId())
        except errors.ReservationError:
          raise errors.OpPrereqError("MAC address %s already in use"
                                     " in cluster" % mac,
                                     errors.ECODE_NOTUNIQUE)

      # bridge verification
      bridge = nic.get("bridge", None)
      link = nic.get("link", None)
      if bridge and link:
        raise errors.OpPrereqError("Cannot pass 'bridge' and 'link'"
                                   " at the same time", errors.ECODE_INVAL)
      elif bridge and nic_mode == constants.NIC_MODE_ROUTED:
        raise errors.OpPrereqError("Cannot pass 'bridge' on a routed nic",
                                   errors.ECODE_INVAL)
      elif bridge:
        link = bridge

      nicparams = {}
      if nic_mode_req:
        nicparams[constants.NIC_MODE] = nic_mode_req
      if link:
        nicparams[constants.NIC_LINK] = link

      check_params = cluster.SimpleFillNIC(nicparams)
      objects.NIC.CheckParameterSyntax(check_params)
      self.nics.append(objects.NIC(mac=mac, ip=nic_ip, nicparams=nicparams))

    # disk checks/pre-build
    self.disks = []
    for disk in self.op.disks:
      mode = disk.get("mode", constants.DISK_RDWR)
      if mode not in constants.DISK_ACCESS_SET:
        raise errors.OpPrereqError("Invalid disk access mode '%s'" %
                                   mode, errors.ECODE_INVAL)
      size = disk.get("size", None)
      if size is None:
        raise errors.OpPrereqError("Missing disk size", errors.ECODE_INVAL)
      try:
        size = int(size)
      except (TypeError, ValueError):
        raise errors.OpPrereqError("Invalid disk size '%s'" % size,
                                   errors.ECODE_INVAL)
      new_disk = {"size": size, "mode": mode}
      if "adopt" in disk:
        new_disk["adopt"] = disk["adopt"]
      self.disks.append(new_disk)

    if self.op.mode == constants.INSTANCE_IMPORT:

      # Check that the new instance doesn't have less disks than the export
      instance_disks = len(self.disks)
      export_disks = export_info.getint(constants.INISECT_INS, 'disk_count')
      if instance_disks < export_disks:
        raise errors.OpPrereqError("Not enough disks to import."
                                   " (instance: %d, export: %d)" %
                                   (instance_disks, export_disks),
                                   errors.ECODE_INVAL)

      disk_images = []
      for idx in range(export_disks):
        option = 'disk%d_dump' % idx
        if export_info.has_option(constants.INISECT_INS, option):
          # FIXME: are the old os-es, disk sizes, etc. useful?
          export_name = export_info.get(constants.INISECT_INS, option)
          image = utils.PathJoin(self.op.src_path, export_name)
          disk_images.append(image)
        else:
          disk_images.append(False)

      self.src_images = disk_images

      old_name = export_info.get(constants.INISECT_INS, 'name')
      try:
        exp_nic_count = export_info.getint(constants.INISECT_INS, 'nic_count')
      except (TypeError, ValueError), err:
        raise errors.OpPrereqError("Invalid export file, nic_count is not"
                                   " an integer: %s" % str(err),
                                   errors.ECODE_STATE)
      if self.op.instance_name == old_name:
        for idx, nic in enumerate(self.nics):
          if nic.mac == constants.VALUE_AUTO and exp_nic_count >= idx:
            nic_mac_ini = 'nic%d_mac' % idx
            nic.mac = export_info.get(constants.INISECT_INS, nic_mac_ini)

    # ENDIF: self.op.mode == constants.INSTANCE_IMPORT

    # ip ping checks (we use the same ip that was resolved in ExpandNames)
    if self.op.ip_check:
      if utils.TcpPing(self.check_ip, constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("IP %s of instance %s already in use" %
                                   (self.check_ip, self.op.instance_name),
                                   errors.ECODE_NOTUNIQUE)

    #### mac address generation
    # By generating here the mac address both the allocator and the hooks get
    # the real final mac address rather than the 'auto' or 'generate' value.
    # There is a race condition between the generation and the instance object
    # creation, which means that we know the mac is valid now, but we're not
    # sure it will be when we actually add the instance. If things go bad
    # adding the instance will abort because of a duplicate mac, and the
    # creation job will fail.
    for nic in self.nics:
      if nic.mac in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
        nic.mac = self.cfg.GenerateMAC(self.proc.GetECId())

    #### allocator run

    if self.op.iallocator is not None:
      self._RunAllocator()

    #### node related checks

    # check primary node
    self.pnode = pnode = self.cfg.GetNodeInfo(self.op.pnode)
    assert self.pnode is not None, \
      "Cannot retrieve locked node %s" % self.op.pnode
    if pnode.offline:
      raise errors.OpPrereqError("Cannot use offline primary node '%s'" %
                                 pnode.name, errors.ECODE_STATE)
    if pnode.drained:
      raise errors.OpPrereqError("Cannot use drained primary node '%s'" %
                                 pnode.name, errors.ECODE_STATE)

    self.secondaries = []

    # mirror node verification
    if self.op.disk_template in constants.DTS_NET_MIRROR:
      if self.op.snode is None:
        raise errors.OpPrereqError("The networked disk templates need"
                                   " a mirror node", errors.ECODE_INVAL)
      if self.op.snode == pnode.name:
        raise errors.OpPrereqError("The secondary node cannot be the"
                                   " primary node.", errors.ECODE_INVAL)
      _CheckNodeOnline(self, self.op.snode)
      _CheckNodeNotDrained(self, self.op.snode)
      self.secondaries.append(self.op.snode)

    nodenames = [pnode.name] + self.secondaries

    req_size = _ComputeDiskSize(self.op.disk_template,
                                self.disks)

    # Check lv size requirements, if not adopting
    if req_size is not None and not self.adopt_disks:
      _CheckNodesFreeDisk(self, nodenames, req_size)

    if self.adopt_disks: # instead, we must check the adoption data
      all_lvs = set([i["adopt"] for i in self.disks])
      if len(all_lvs) != len(self.disks):
        raise errors.OpPrereqError("Duplicate volume names given for adoption",
                                   errors.ECODE_INVAL)
      for lv_name in all_lvs:
        try:
          self.cfg.ReserveLV(lv_name, self.proc.GetECId())
        except errors.ReservationError:
          raise errors.OpPrereqError("LV named %s used by another instance" %
                                     lv_name, errors.ECODE_NOTUNIQUE)

      node_lvs = self.rpc.call_lv_list([pnode.name],
                                       self.cfg.GetVGName())[pnode.name]
      node_lvs.Raise("Cannot get LV information from node %s" % pnode.name)
      node_lvs = node_lvs.payload
      delta = all_lvs.difference(node_lvs.keys())
      if delta:
        raise errors.OpPrereqError("Missing logical volume(s): %s" %
                                   utils.CommaJoin(delta),
                                   errors.ECODE_INVAL)
      online_lvs = [lv for lv in all_lvs if node_lvs[lv][2]]
      if online_lvs:
        raise errors.OpPrereqError("Online logical volumes found, cannot"
                                   " adopt: %s" % utils.CommaJoin(online_lvs),
                                   errors.ECODE_STATE)
      # update the size of disk based on what is found
      for dsk in self.disks:
        dsk["size"] = int(float(node_lvs[dsk["adopt"]][0]))

    _CheckHVParams(self, nodenames, self.op.hypervisor, self.op.hvparams)

    _CheckNodeHasOS(self, pnode.name, self.op.os_type, self.op.force_variant)

    _CheckNicsBridgesExist(self, self.nics, self.pnode.name)

    # memory check on primary node
    if self.op.start:
      _CheckNodeFreeMemory(self, self.pnode.name,
                           "creating instance %s" % self.op.instance_name,
                           self.be_full[constants.BE_MEMORY],
                           self.op.hypervisor)

    self.dry_run_result = list(nodenames)

  def Exec(self, feedback_fn):
    """Create and add the instance to the cluster.

    """
    instance = self.op.instance_name
    pnode_name = self.pnode.name

    ht_kind = self.op.hypervisor
    if ht_kind in constants.HTS_REQ_PORT:
      network_port = self.cfg.AllocatePort()
    else:
      network_port = None

    if constants.ENABLE_FILE_STORAGE:
      # this is needed because os.path.join does not accept None arguments
      if self.op.file_storage_dir is None:
        string_file_storage_dir = ""
      else:
        string_file_storage_dir = self.op.file_storage_dir

      # build the full file storage dir path
      file_storage_dir = utils.PathJoin(self.cfg.GetFileStorageDir(),
                                        string_file_storage_dir, instance)
    else:
      file_storage_dir = ""

    disks = _GenerateDiskTemplate(self,
                                  self.op.disk_template,
                                  instance, pnode_name,
                                  self.secondaries,
                                  self.disks,
                                  file_storage_dir,
                                  self.op.file_driver,
                                  0)

    iobj = objects.Instance(name=instance, os=self.op.os_type,
                            primary_node=pnode_name,
                            nics=self.nics, disks=disks,
                            disk_template=self.op.disk_template,
                            admin_up=False,
                            network_port=network_port,
                            beparams=self.op.beparams,
                            hvparams=self.op.hvparams,
                            hypervisor=self.op.hypervisor,
                            )

    if self.adopt_disks:
      # rename LVs to the newly-generated names; we need to construct
      # 'fake' LV disks with the old data, plus the new unique_id
      tmp_disks = [objects.Disk.FromDict(v.ToDict()) for v in disks]
      rename_to = []
      for t_dsk, a_dsk in zip (tmp_disks, self.disks):
        rename_to.append(t_dsk.logical_id)
        t_dsk.logical_id = (t_dsk.logical_id[0], a_dsk["adopt"])
        self.cfg.SetDiskID(t_dsk, pnode_name)
      result = self.rpc.call_blockdev_rename(pnode_name,
                                             zip(tmp_disks, rename_to))
      result.Raise("Failed to rename adoped LVs")
    else:
      feedback_fn("* creating instance disks...")
      try:
        _CreateDisks(self, iobj)
      except errors.OpExecError:
        self.LogWarning("Device creation failed, reverting...")
        try:
          _RemoveDisks(self, iobj)
        finally:
          self.cfg.ReleaseDRBDMinors(instance)
          raise

    feedback_fn("adding instance %s to cluster config" % instance)

    self.cfg.AddInstance(iobj, self.proc.GetECId())

    # Declare that we don't want to remove the instance lock anymore, as we've
    # added the instance to the config
    del self.remove_locks[locking.LEVEL_INSTANCE]
    # Unlock all the nodes
    if self.op.mode == constants.INSTANCE_IMPORT:
      nodes_keep = [self.op.src_node]
      nodes_release = [node for node in self.acquired_locks[locking.LEVEL_NODE]
                       if node != self.op.src_node]
      self.context.glm.release(locking.LEVEL_NODE, nodes_release)
      self.acquired_locks[locking.LEVEL_NODE] = nodes_keep
    else:
      self.context.glm.release(locking.LEVEL_NODE)
      del self.acquired_locks[locking.LEVEL_NODE]

    if self.op.wait_for_sync:
      disk_abort = not _WaitForSync(self, iobj)
    elif iobj.disk_template in constants.DTS_NET_MIRROR:
      # make sure the disks are not degraded (still sync-ing is ok)
      time.sleep(15)
      feedback_fn("* checking mirrors status")
      disk_abort = not _WaitForSync(self, iobj, oneshot=True)
    else:
      disk_abort = False

    if disk_abort:
      _RemoveDisks(self, iobj)
      self.cfg.RemoveInstance(iobj.name)
      # Make sure the instance lock gets removed
      self.remove_locks[locking.LEVEL_INSTANCE] = iobj.name
      raise errors.OpExecError("There are some degraded disks for"
                               " this instance")

    if iobj.disk_template != constants.DT_DISKLESS and not self.adopt_disks:
      if self.op.mode == constants.INSTANCE_CREATE:
        if not self.op.no_install:
          feedback_fn("* running the instance OS create scripts...")
          # FIXME: pass debug option from opcode to backend
          result = self.rpc.call_instance_os_add(pnode_name, iobj, False,
                                                 self.op.debug_level)
          result.Raise("Could not add os for instance %s"
                       " on node %s" % (instance, pnode_name))

      elif self.op.mode == constants.INSTANCE_IMPORT:
        feedback_fn("* running the instance OS import scripts...")

        transfers = []

        for idx, image in enumerate(self.src_images):
          if not image:
            continue

          # FIXME: pass debug option from opcode to backend
          dt = masterd.instance.DiskTransfer("disk/%s" % idx,
                                             constants.IEIO_FILE, (image, ),
                                             constants.IEIO_SCRIPT,
                                             (iobj.disks[idx], idx),
                                             None)
          transfers.append(dt)

        import_result = \
          masterd.instance.TransferInstanceData(self, feedback_fn,
                                                self.op.src_node, pnode_name,
                                                self.pnode.secondary_ip,
                                                iobj, transfers)
        if not compat.all(import_result):
          self.LogWarning("Some disks for instance %s on node %s were not"
                          " imported successfully" % (instance, pnode_name))

      elif self.op.mode == constants.INSTANCE_REMOTE_IMPORT:
        feedback_fn("* preparing remote import...")
        connect_timeout = constants.RIE_CONNECT_TIMEOUT
        timeouts = masterd.instance.ImportExportTimeouts(connect_timeout)

        disk_results = masterd.instance.RemoteImport(self, feedback_fn, iobj,
                                                     self.source_x509_ca,
                                                     self._cds, timeouts)
        if not compat.all(disk_results):
          # TODO: Should the instance still be started, even if some disks
          # failed to import (valid for local imports, too)?
          self.LogWarning("Some disks for instance %s on node %s were not"
                          " imported successfully" % (instance, pnode_name))

        # Run rename script on newly imported instance
        assert iobj.name == instance
        feedback_fn("Running rename script for %s" % instance)
        result = self.rpc.call_instance_run_rename(pnode_name, iobj,
                                                   self.source_instance_name,
                                                   self.op.debug_level)
        if result.fail_msg:
          self.LogWarning("Failed to run rename script for %s on node"
                          " %s: %s" % (instance, pnode_name, result.fail_msg))

      else:
        # also checked in the prereq part
        raise errors.ProgrammerError("Unknown OS initialization mode '%s'"
                                     % self.op.mode)

    if self.op.start:
      iobj.admin_up = True
      self.cfg.Update(iobj, feedback_fn)
      logging.info("Starting instance %s on node %s", instance, pnode_name)
      feedback_fn("* starting instance...")
      result = self.rpc.call_instance_start(pnode_name, iobj, None, None)
      result.Raise("Could not start instance")

    return list(iobj.all_nodes)


class LUConnectConsole(NoHooksLU):
  """Connect to an instance's console.

  This is somewhat special in that it returns the command line that
  you need to run on the master node in order to connect to the
  console.

  """
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, self.instance.primary_node)

  def Exec(self, feedback_fn):
    """Connect to the console of an instance

    """
    instance = self.instance
    node = instance.primary_node

    node_insts = self.rpc.call_instance_list([node],
                                             [instance.hypervisor])[node]
    node_insts.Raise("Can't get node information from %s" % node)

    if instance.name not in node_insts.payload:
      raise errors.OpExecError("Instance %s is not running." % instance.name)

    logging.debug("Connecting to console of %s on %s", instance.name, node)

    hyper = hypervisor.GetHypervisor(instance.hypervisor)
    cluster = self.cfg.GetClusterInfo()
    # beparams and hvparams are passed separately, to avoid editing the
    # instance and then saving the defaults in the instance itself.
    hvparams = cluster.FillHV(instance)
    beparams = cluster.FillBE(instance)
    console_cmd = hyper.GetShellCommandForConsole(instance, hvparams, beparams)

    # build ssh cmdline
    return self.ssh.BuildCmd(node, "root", console_cmd, batch=True, tty=True)


class LUReplaceDisks(LogicalUnit):
  """Replace the disks of an instance.

  """
  HPATH = "mirrors-replace"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "mode", "disks"]
  REQ_BGL = False

  def CheckArguments(self):
    if not hasattr(self.op, "remote_node"):
      self.op.remote_node = None
    if not hasattr(self.op, "iallocator"):
      self.op.iallocator = None
    if not hasattr(self.op, "early_release"):
      self.op.early_release = False

    TLReplaceDisks.CheckArguments(self.op.mode, self.op.remote_node,
                                  self.op.iallocator)

  def ExpandNames(self):
    self._ExpandAndLockInstance()

    if self.op.iallocator is not None:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

    elif self.op.remote_node is not None:
      remote_node = _ExpandNodeName(self.cfg, self.op.remote_node)
      self.op.remote_node = remote_node

      # Warning: do not remove the locking of the new secondary here
      # unless DRBD8.AddChildren is changed to work in parallel;
      # currently it doesn't since parallel invocations of
      # FindUnusedMinor will conflict
      self.needed_locks[locking.LEVEL_NODE] = [remote_node]
      self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_APPEND

    else:
      self.needed_locks[locking.LEVEL_NODE] = []
      self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

    self.replacer = TLReplaceDisks(self, self.op.instance_name, self.op.mode,
                                   self.op.iallocator, self.op.remote_node,
                                   self.op.disks, False, self.op.early_release)

    self.tasklets = [self.replacer]

  def DeclareLocks(self, level):
    # If we're not already locking all nodes in the set we have to declare the
    # instance's primary/secondary nodes.
    if (level == locking.LEVEL_NODE and
        self.needed_locks[locking.LEVEL_NODE] is not locking.ALL_SET):
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master, the primary and all the secondaries.

    """
    instance = self.replacer.instance
    env = {
      "MODE": self.op.mode,
      "NEW_SECONDARY": self.op.remote_node,
      "OLD_SECONDARY": instance.secondary_nodes[0],
      }
    env.update(_BuildInstanceHookEnvByObject(self, instance))
    nl = [
      self.cfg.GetMasterNode(),
      instance.primary_node,
      ]
    if self.op.remote_node is not None:
      nl.append(self.op.remote_node)
    return env, nl, nl


class LUEvacuateNode(LogicalUnit):
  """Relocate the secondary instances from a node.

  """
  HPATH = "node-evacuate"
  HTYPE = constants.HTYPE_NODE
  _OP_REQP = ["node_name"]
  REQ_BGL = False

  def CheckArguments(self):
    if not hasattr(self.op, "remote_node"):
      self.op.remote_node = None
    if not hasattr(self.op, "iallocator"):
      self.op.iallocator = None
    if not hasattr(self.op, "early_release"):
      self.op.early_release = False

    TLReplaceDisks.CheckArguments(constants.REPLACE_DISK_CHG,
                                  self.op.remote_node,
                                  self.op.iallocator)

  def ExpandNames(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)

    self.needed_locks = {}

    # Declare node locks
    if self.op.iallocator is not None:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

    elif self.op.remote_node is not None:
      self.op.remote_node = _ExpandNodeName(self.cfg, self.op.remote_node)

      # Warning: do not remove the locking of the new secondary here
      # unless DRBD8.AddChildren is changed to work in parallel;
      # currently it doesn't since parallel invocations of
      # FindUnusedMinor will conflict
      self.needed_locks[locking.LEVEL_NODE] = [self.op.remote_node]
      self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_APPEND

    else:
      raise errors.OpPrereqError("Invalid parameters", errors.ECODE_INVAL)

    # Create tasklets for replacing disks for all secondary instances on this
    # node
    names = []
    tasklets = []

    for inst in _GetNodeSecondaryInstances(self.cfg, self.op.node_name):
      logging.debug("Replacing disks for instance %s", inst.name)
      names.append(inst.name)

      replacer = TLReplaceDisks(self, inst.name, constants.REPLACE_DISK_CHG,
                                self.op.iallocator, self.op.remote_node, [],
                                True, self.op.early_release)
      tasklets.append(replacer)

    self.tasklets = tasklets
    self.instance_names = names

    # Declare instance locks
    self.needed_locks[locking.LEVEL_INSTANCE] = self.instance_names

  def DeclareLocks(self, level):
    # If we're not already locking all nodes in the set we have to declare the
    # instance's primary/secondary nodes.
    if (level == locking.LEVEL_NODE and
        self.needed_locks[locking.LEVEL_NODE] is not locking.ALL_SET):
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "NODE_NAME": self.op.node_name,
      }

    nl = [self.cfg.GetMasterNode()]

    if self.op.remote_node is not None:
      env["NEW_SECONDARY"] = self.op.remote_node
      nl.append(self.op.remote_node)

    return (env, nl, nl)


class TLReplaceDisks(Tasklet):
  """Replaces disks for an instance.

  Note: Locking is not within the scope of this class.

  """
  def __init__(self, lu, instance_name, mode, iallocator_name, remote_node,
               disks, delay_iallocator, early_release):
    """Initializes this class.

    """
    Tasklet.__init__(self, lu)

    # Parameters
    self.instance_name = instance_name
    self.mode = mode
    self.iallocator_name = iallocator_name
    self.remote_node = remote_node
    self.disks = disks
    self.delay_iallocator = delay_iallocator
    self.early_release = early_release

    # Runtime data
    self.instance = None
    self.new_node = None
    self.target_node = None
    self.other_node = None
    self.remote_node_info = None
    self.node_secondary_ip = None

  @staticmethod
  def CheckArguments(mode, remote_node, iallocator):
    """Helper function for users of this class.

    """
    # check for valid parameter combination
    if mode == constants.REPLACE_DISK_CHG:
      if remote_node is None and iallocator is None:
        raise errors.OpPrereqError("When changing the secondary either an"
                                   " iallocator script must be used or the"
                                   " new node given", errors.ECODE_INVAL)

      if remote_node is not None and iallocator is not None:
        raise errors.OpPrereqError("Give either the iallocator or the new"
                                   " secondary, not both", errors.ECODE_INVAL)

    elif remote_node is not None or iallocator is not None:
      # Not replacing the secondary
      raise errors.OpPrereqError("The iallocator and new node options can"
                                 " only be used when changing the"
                                 " secondary node", errors.ECODE_INVAL)

  @staticmethod
  def _RunAllocator(lu, iallocator_name, instance_name, relocate_from):
    """Compute a new secondary node using an IAllocator.

    """
    ial = IAllocator(lu.cfg, lu.rpc,
                     mode=constants.IALLOCATOR_MODE_RELOC,
                     name=instance_name,
                     relocate_from=relocate_from)

    ial.Run(iallocator_name)

    if not ial.success:
      raise errors.OpPrereqError("Can't compute nodes using iallocator '%s':"
                                 " %s" % (iallocator_name, ial.info),
                                 errors.ECODE_NORES)

    if len(ial.result) != ial.required_nodes:
      raise errors.OpPrereqError("iallocator '%s' returned invalid number"
                                 " of nodes (%s), required %s" %
                                 (iallocator_name,
                                  len(ial.result), ial.required_nodes),
                                 errors.ECODE_FAULT)

    remote_node_name = ial.result[0]

    lu.LogInfo("Selected new secondary for instance '%s': %s",
               instance_name, remote_node_name)

    return remote_node_name

  def _FindFaultyDisks(self, node_name):
    return _FindFaultyInstanceDisks(self.cfg, self.rpc, self.instance,
                                    node_name, True)

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    self.instance = instance = self.cfg.GetInstanceInfo(self.instance_name)
    assert instance is not None, \
      "Cannot retrieve locked instance %s" % self.instance_name

    if instance.disk_template != constants.DT_DRBD8:
      raise errors.OpPrereqError("Can only run replace disks for DRBD8-based"
                                 " instances", errors.ECODE_INVAL)

    if len(instance.secondary_nodes) != 1:
      raise errors.OpPrereqError("The instance has a strange layout,"
                                 " expected one secondary but found %d" %
                                 len(instance.secondary_nodes),
                                 errors.ECODE_FAULT)

    if not self.delay_iallocator:
      self._CheckPrereq2()

  def _CheckPrereq2(self):
    """Check prerequisites, second part.

    This function should always be part of CheckPrereq. It was separated and is
    now called from Exec because during node evacuation iallocator was only
    called with an unmodified cluster model, not taking planned changes into
    account.

    """
    instance = self.instance
    secondary_node = instance.secondary_nodes[0]

    if self.iallocator_name is None:
      remote_node = self.remote_node
    else:
      remote_node = self._RunAllocator(self.lu, self.iallocator_name,
                                       instance.name, instance.secondary_nodes)

    if remote_node is not None:
      self.remote_node_info = self.cfg.GetNodeInfo(remote_node)
      assert self.remote_node_info is not None, \
        "Cannot retrieve locked node %s" % remote_node
    else:
      self.remote_node_info = None

    if remote_node == self.instance.primary_node:
      raise errors.OpPrereqError("The specified node is the primary node of"
                                 " the instance.", errors.ECODE_INVAL)

    if remote_node == secondary_node:
      raise errors.OpPrereqError("The specified node is already the"
                                 " secondary node of the instance.",
                                 errors.ECODE_INVAL)

    if self.disks and self.mode in (constants.REPLACE_DISK_AUTO,
                                    constants.REPLACE_DISK_CHG):
      raise errors.OpPrereqError("Cannot specify disks to be replaced",
                                 errors.ECODE_INVAL)

    if self.mode == constants.REPLACE_DISK_AUTO:
      faulty_primary = self._FindFaultyDisks(instance.primary_node)
      faulty_secondary = self._FindFaultyDisks(secondary_node)

      if faulty_primary and faulty_secondary:
        raise errors.OpPrereqError("Instance %s has faulty disks on more than"
                                   " one node and can not be repaired"
                                   " automatically" % self.instance_name,
                                   errors.ECODE_STATE)

      if faulty_primary:
        self.disks = faulty_primary
        self.target_node = instance.primary_node
        self.other_node = secondary_node
        check_nodes = [self.target_node, self.other_node]
      elif faulty_secondary:
        self.disks = faulty_secondary
        self.target_node = secondary_node
        self.other_node = instance.primary_node
        check_nodes = [self.target_node, self.other_node]
      else:
        self.disks = []
        check_nodes = []

    else:
      # Non-automatic modes
      if self.mode == constants.REPLACE_DISK_PRI:
        self.target_node = instance.primary_node
        self.other_node = secondary_node
        check_nodes = [self.target_node, self.other_node]

      elif self.mode == constants.REPLACE_DISK_SEC:
        self.target_node = secondary_node
        self.other_node = instance.primary_node
        check_nodes = [self.target_node, self.other_node]

      elif self.mode == constants.REPLACE_DISK_CHG:
        self.new_node = remote_node
        self.other_node = instance.primary_node
        self.target_node = secondary_node
        check_nodes = [self.new_node, self.other_node]

        _CheckNodeNotDrained(self.lu, remote_node)

        old_node_info = self.cfg.GetNodeInfo(secondary_node)
        assert old_node_info is not None
        if old_node_info.offline and not self.early_release:
          # doesn't make sense to delay the release
          self.early_release = True
          self.lu.LogInfo("Old secondary %s is offline, automatically enabling"
                          " early-release mode", secondary_node)

      else:
        raise errors.ProgrammerError("Unhandled disk replace mode (%s)" %
                                     self.mode)

      # If not specified all disks should be replaced
      if not self.disks:
        self.disks = range(len(self.instance.disks))

    for node in check_nodes:
      _CheckNodeOnline(self.lu, node)

    # Check whether disks are valid
    for disk_idx in self.disks:
      instance.FindDisk(disk_idx)

    # Get secondary node IP addresses
    node_2nd_ip = {}

    for node_name in [self.target_node, self.other_node, self.new_node]:
      if node_name is not None:
        node_2nd_ip[node_name] = self.cfg.GetNodeInfo(node_name).secondary_ip

    self.node_secondary_ip = node_2nd_ip

  def Exec(self, feedback_fn):
    """Execute disk replacement.

    This dispatches the disk replacement to the appropriate handler.

    """
    if self.delay_iallocator:
      self._CheckPrereq2()

    if not self.disks:
      feedback_fn("No disks need replacement")
      return

    feedback_fn("Replacing disk(s) %s for %s" %
                (utils.CommaJoin(self.disks), self.instance.name))

    activate_disks = (not self.instance.admin_up)

    # Activate the instance disks if we're replacing them on a down instance
    if activate_disks:
      _StartInstanceDisks(self.lu, self.instance, True)

    try:
      # Should we replace the secondary node?
      if self.new_node is not None:
        fn = self._ExecDrbd8Secondary
      else:
        fn = self._ExecDrbd8DiskOnly

      return fn(feedback_fn)

    finally:
      # Deactivate the instance disks if we're replacing them on a
      # down instance
      if activate_disks:
        _SafeShutdownInstanceDisks(self.lu, self.instance)

  def _CheckVolumeGroup(self, nodes):
    self.lu.LogInfo("Checking volume groups")

    vgname = self.cfg.GetVGName()

    # Make sure volume group exists on all involved nodes
    results = self.rpc.call_vg_list(nodes)
    if not results:
      raise errors.OpExecError("Can't list volume groups on the nodes")

    for node in nodes:
      res = results[node]
      res.Raise("Error checking node %s" % node)
      if vgname not in res.payload:
        raise errors.OpExecError("Volume group '%s' not found on node %s" %
                                 (vgname, node))

  def _CheckDisksExistence(self, nodes):
    # Check disk existence
    for idx, dev in enumerate(self.instance.disks):
      if idx not in self.disks:
        continue

      for node in nodes:
        self.lu.LogInfo("Checking disk/%d on %s" % (idx, node))
        self.cfg.SetDiskID(dev, node)

        result = self.rpc.call_blockdev_find(node, dev)

        msg = result.fail_msg
        if msg or not result.payload:
          if not msg:
            msg = "disk not found"
          raise errors.OpExecError("Can't find disk/%d on node %s: %s" %
                                   (idx, node, msg))

  def _CheckDisksConsistency(self, node_name, on_primary, ldisk):
    for idx, dev in enumerate(self.instance.disks):
      if idx not in self.disks:
        continue

      self.lu.LogInfo("Checking disk/%d consistency on node %s" %
                      (idx, node_name))

      if not _CheckDiskConsistency(self.lu, dev, node_name, on_primary,
                                   ldisk=ldisk):
        raise errors.OpExecError("Node %s has degraded storage, unsafe to"
                                 " replace disks for instance %s" %
                                 (node_name, self.instance.name))

  def _CreateNewStorage(self, node_name):
    vgname = self.cfg.GetVGName()
    iv_names = {}

    for idx, dev in enumerate(self.instance.disks):
      if idx not in self.disks:
        continue

      self.lu.LogInfo("Adding storage on %s for disk/%d" % (node_name, idx))

      self.cfg.SetDiskID(dev, node_name)

      lv_names = [".disk%d_%s" % (idx, suffix) for suffix in ["data", "meta"]]
      names = _GenerateUniqueNames(self.lu, lv_names)

      lv_data = objects.Disk(dev_type=constants.LD_LV, size=dev.size,
                             logical_id=(vgname, names[0]))
      lv_meta = objects.Disk(dev_type=constants.LD_LV, size=128,
                             logical_id=(vgname, names[1]))

      new_lvs = [lv_data, lv_meta]
      old_lvs = dev.children
      iv_names[dev.iv_name] = (dev, old_lvs, new_lvs)

      # we pass force_create=True to force the LVM creation
      for new_lv in new_lvs:
        _CreateBlockDev(self.lu, node_name, self.instance, new_lv, True,
                        _GetInstanceInfoText(self.instance), False)

    return iv_names

  def _CheckDevices(self, node_name, iv_names):
    for name, (dev, _, _) in iv_names.iteritems():
      self.cfg.SetDiskID(dev, node_name)

      result = self.rpc.call_blockdev_find(node_name, dev)

      msg = result.fail_msg
      if msg or not result.payload:
        if not msg:
          msg = "disk not found"
        raise errors.OpExecError("Can't find DRBD device %s: %s" %
                                 (name, msg))

      if result.payload.is_degraded:
        raise errors.OpExecError("DRBD device %s is degraded!" % name)

  def _RemoveOldStorage(self, node_name, iv_names):
    for name, (_, old_lvs, _) in iv_names.iteritems():
      self.lu.LogInfo("Remove logical volumes for %s" % name)

      for lv in old_lvs:
        self.cfg.SetDiskID(lv, node_name)

        msg = self.rpc.call_blockdev_remove(node_name, lv).fail_msg
        if msg:
          self.lu.LogWarning("Can't remove old LV: %s" % msg,
                             hint="remove unused LVs manually")

  def _ReleaseNodeLock(self, node_name):
    """Releases the lock for a given node."""
    self.lu.context.glm.release(locking.LEVEL_NODE, node_name)

  def _ExecDrbd8DiskOnly(self, feedback_fn):
    """Replace a disk on the primary or secondary for DRBD 8.

    The algorithm for replace is quite complicated:

      1. for each disk to be replaced:

        1. create new LVs on the target node with unique names
        1. detach old LVs from the drbd device
        1. rename old LVs to name_replaced.<time_t>
        1. rename new LVs to old LVs
        1. attach the new LVs (with the old names now) to the drbd device

      1. wait for sync across all devices

      1. for each modified disk:

        1. remove old LVs (which have the name name_replaces.<time_t>)

    Failures are not very well handled.

    """
    steps_total = 6

    # Step: check device activation
    self.lu.LogStep(1, steps_total, "Check device existence")
    self._CheckDisksExistence([self.other_node, self.target_node])
    self._CheckVolumeGroup([self.target_node, self.other_node])

    # Step: check other node consistency
    self.lu.LogStep(2, steps_total, "Check peer consistency")
    self._CheckDisksConsistency(self.other_node,
                                self.other_node == self.instance.primary_node,
                                False)

    # Step: create new storage
    self.lu.LogStep(3, steps_total, "Allocate new storage")
    iv_names = self._CreateNewStorage(self.target_node)

    # Step: for each lv, detach+rename*2+attach
    self.lu.LogStep(4, steps_total, "Changing drbd configuration")
    for dev, old_lvs, new_lvs in iv_names.itervalues():
      self.lu.LogInfo("Detaching %s drbd from local storage" % dev.iv_name)

      result = self.rpc.call_blockdev_removechildren(self.target_node, dev,
                                                     old_lvs)
      result.Raise("Can't detach drbd from local storage on node"
                   " %s for device %s" % (self.target_node, dev.iv_name))
      #dev.children = []
      #cfg.Update(instance)

      # ok, we created the new LVs, so now we know we have the needed
      # storage; as such, we proceed on the target node to rename
      # old_lv to _old, and new_lv to old_lv; note that we rename LVs
      # using the assumption that logical_id == physical_id (which in
      # turn is the unique_id on that node)

      # FIXME(iustin): use a better name for the replaced LVs
      temp_suffix = int(time.time())
      ren_fn = lambda d, suff: (d.physical_id[0],
                                d.physical_id[1] + "_replaced-%s" % suff)

      # Build the rename list based on what LVs exist on the node
      rename_old_to_new = []
      for to_ren in old_lvs:
        result = self.rpc.call_blockdev_find(self.target_node, to_ren)
        if not result.fail_msg and result.payload:
          # device exists
          rename_old_to_new.append((to_ren, ren_fn(to_ren, temp_suffix)))

      self.lu.LogInfo("Renaming the old LVs on the target node")
      result = self.rpc.call_blockdev_rename(self.target_node,
                                             rename_old_to_new)
      result.Raise("Can't rename old LVs on node %s" % self.target_node)

      # Now we rename the new LVs to the old LVs
      self.lu.LogInfo("Renaming the new LVs on the target node")
      rename_new_to_old = [(new, old.physical_id)
                           for old, new in zip(old_lvs, new_lvs)]
      result = self.rpc.call_blockdev_rename(self.target_node,
                                             rename_new_to_old)
      result.Raise("Can't rename new LVs on node %s" % self.target_node)

      for old, new in zip(old_lvs, new_lvs):
        new.logical_id = old.logical_id
        self.cfg.SetDiskID(new, self.target_node)

      for disk in old_lvs:
        disk.logical_id = ren_fn(disk, temp_suffix)
        self.cfg.SetDiskID(disk, self.target_node)

      # Now that the new lvs have the old name, we can add them to the device
      self.lu.LogInfo("Adding new mirror component on %s" % self.target_node)
      result = self.rpc.call_blockdev_addchildren(self.target_node, dev,
                                                  new_lvs)
      msg = result.fail_msg
      if msg:
        for new_lv in new_lvs:
          msg2 = self.rpc.call_blockdev_remove(self.target_node,
                                               new_lv).fail_msg
          if msg2:
            self.lu.LogWarning("Can't rollback device %s: %s", dev, msg2,
                               hint=("cleanup manually the unused logical"
                                     "volumes"))
        raise errors.OpExecError("Can't add local storage to drbd: %s" % msg)

      dev.children = new_lvs

      self.cfg.Update(self.instance, feedback_fn)

    cstep = 5
    if self.early_release:
      self.lu.LogStep(cstep, steps_total, "Removing old storage")
      cstep += 1
      self._RemoveOldStorage(self.target_node, iv_names)
      # WARNING: we release both node locks here, do not do other RPCs
      # than WaitForSync to the primary node
      self._ReleaseNodeLock([self.target_node, self.other_node])

    # Wait for sync
    # This can fail as the old devices are degraded and _WaitForSync
    # does a combined result over all disks, so we don't check its return value
    self.lu.LogStep(cstep, steps_total, "Sync devices")
    cstep += 1
    _WaitForSync(self.lu, self.instance)

    # Check all devices manually
    self._CheckDevices(self.instance.primary_node, iv_names)

    # Step: remove old storage
    if not self.early_release:
      self.lu.LogStep(cstep, steps_total, "Removing old storage")
      cstep += 1
      self._RemoveOldStorage(self.target_node, iv_names)

  def _ExecDrbd8Secondary(self, feedback_fn):
    """Replace the secondary node for DRBD 8.

    The algorithm for replace is quite complicated:
      - for all disks of the instance:
        - create new LVs on the new node with same names
        - shutdown the drbd device on the old secondary
        - disconnect the drbd network on the primary
        - create the drbd device on the new secondary
        - network attach the drbd on the primary, using an artifice:
          the drbd code for Attach() will connect to the network if it
          finds a device which is connected to the good local disks but
          not network enabled
      - wait for sync across all devices
      - remove all disks from the old secondary

    Failures are not very well handled.

    """
    steps_total = 6

    # Step: check device activation
    self.lu.LogStep(1, steps_total, "Check device existence")
    self._CheckDisksExistence([self.instance.primary_node])
    self._CheckVolumeGroup([self.instance.primary_node])

    # Step: check other node consistency
    self.lu.LogStep(2, steps_total, "Check peer consistency")
    self._CheckDisksConsistency(self.instance.primary_node, True, True)

    # Step: create new storage
    self.lu.LogStep(3, steps_total, "Allocate new storage")
    for idx, dev in enumerate(self.instance.disks):
      self.lu.LogInfo("Adding new local storage on %s for disk/%d" %
                      (self.new_node, idx))
      # we pass force_create=True to force LVM creation
      for new_lv in dev.children:
        _CreateBlockDev(self.lu, self.new_node, self.instance, new_lv, True,
                        _GetInstanceInfoText(self.instance), False)

    # Step 4: dbrd minors and drbd setups changes
    # after this, we must manually remove the drbd minors on both the
    # error and the success paths
    self.lu.LogStep(4, steps_total, "Changing drbd configuration")
    minors = self.cfg.AllocateDRBDMinor([self.new_node
                                         for dev in self.instance.disks],
                                        self.instance.name)
    logging.debug("Allocated minors %r", minors)

    iv_names = {}
    for idx, (dev, new_minor) in enumerate(zip(self.instance.disks, minors)):
      self.lu.LogInfo("activating a new drbd on %s for disk/%d" %
                      (self.new_node, idx))
      # create new devices on new_node; note that we create two IDs:
      # one without port, so the drbd will be activated without
      # networking information on the new node at this stage, and one
      # with network, for the latter activation in step 4
      (o_node1, o_node2, o_port, o_minor1, o_minor2, o_secret) = dev.logical_id
      if self.instance.primary_node == o_node1:
        p_minor = o_minor1
      else:
        assert self.instance.primary_node == o_node2, "Three-node instance?"
        p_minor = o_minor2

      new_alone_id = (self.instance.primary_node, self.new_node, None,
                      p_minor, new_minor, o_secret)
      new_net_id = (self.instance.primary_node, self.new_node, o_port,
                    p_minor, new_minor, o_secret)

      iv_names[idx] = (dev, dev.children, new_net_id)
      logging.debug("Allocated new_minor: %s, new_logical_id: %s", new_minor,
                    new_net_id)
      new_drbd = objects.Disk(dev_type=constants.LD_DRBD8,
                              logical_id=new_alone_id,
                              children=dev.children,
                              size=dev.size)
      try:
        _CreateSingleBlockDev(self.lu, self.new_node, self.instance, new_drbd,
                              _GetInstanceInfoText(self.instance), False)
      except errors.GenericError:
        self.cfg.ReleaseDRBDMinors(self.instance.name)
        raise

    # We have new devices, shutdown the drbd on the old secondary
    for idx, dev in enumerate(self.instance.disks):
      self.lu.LogInfo("Shutting down drbd for disk/%d on old node" % idx)
      self.cfg.SetDiskID(dev, self.target_node)
      msg = self.rpc.call_blockdev_shutdown(self.target_node, dev).fail_msg
      if msg:
        self.lu.LogWarning("Failed to shutdown drbd for disk/%d on old"
                           "node: %s" % (idx, msg),
                           hint=("Please cleanup this device manually as"
                                 " soon as possible"))

    self.lu.LogInfo("Detaching primary drbds from the network (=> standalone)")
    result = self.rpc.call_drbd_disconnect_net([self.instance.primary_node],
                                               self.node_secondary_ip,
                                               self.instance.disks)\
                                              [self.instance.primary_node]

    msg = result.fail_msg
    if msg:
      # detaches didn't succeed (unlikely)
      self.cfg.ReleaseDRBDMinors(self.instance.name)
      raise errors.OpExecError("Can't detach the disks from the network on"
                               " old node: %s" % (msg,))

    # if we managed to detach at least one, we update all the disks of
    # the instance to point to the new secondary
    self.lu.LogInfo("Updating instance configuration")
    for dev, _, new_logical_id in iv_names.itervalues():
      dev.logical_id = new_logical_id
      self.cfg.SetDiskID(dev, self.instance.primary_node)

    self.cfg.Update(self.instance, feedback_fn)

    # and now perform the drbd attach
    self.lu.LogInfo("Attaching primary drbds to new secondary"
                    " (standalone => connected)")
    result = self.rpc.call_drbd_attach_net([self.instance.primary_node,
                                            self.new_node],
                                           self.node_secondary_ip,
                                           self.instance.disks,
                                           self.instance.name,
                                           False)
    for to_node, to_result in result.items():
      msg = to_result.fail_msg
      if msg:
        self.lu.LogWarning("Can't attach drbd disks on node %s: %s",
                           to_node, msg,
                           hint=("please do a gnt-instance info to see the"
                                 " status of disks"))
    cstep = 5
    if self.early_release:
      self.lu.LogStep(cstep, steps_total, "Removing old storage")
      cstep += 1
      self._RemoveOldStorage(self.target_node, iv_names)
      # WARNING: we release all node locks here, do not do other RPCs
      # than WaitForSync to the primary node
      self._ReleaseNodeLock([self.instance.primary_node,
                             self.target_node,
                             self.new_node])

    # Wait for sync
    # This can fail as the old devices are degraded and _WaitForSync
    # does a combined result over all disks, so we don't check its return value
    self.lu.LogStep(cstep, steps_total, "Sync devices")
    cstep += 1
    _WaitForSync(self.lu, self.instance)

    # Check all devices manually
    self._CheckDevices(self.instance.primary_node, iv_names)

    # Step: remove old storage
    if not self.early_release:
      self.lu.LogStep(cstep, steps_total, "Removing old storage")
      self._RemoveOldStorage(self.target_node, iv_names)


class LURepairNodeStorage(NoHooksLU):
  """Repairs the volume group on a node.

  """
  _OP_REQP = ["node_name"]
  REQ_BGL = False

  def CheckArguments(self):
    self.op.node_name = _ExpandNodeName(self.cfg, self.op.node_name)

    _CheckStorageType(self.op.storage_type)

  def ExpandNames(self):
    self.needed_locks = {
      locking.LEVEL_NODE: [self.op.node_name],
      }

  def _CheckFaultyDisks(self, instance, node_name):
    """Ensure faulty disks abort the opcode or at least warn."""
    try:
      if _FindFaultyInstanceDisks(self.cfg, self.rpc, instance,
                                  node_name, True):
        raise errors.OpPrereqError("Instance '%s' has faulty disks on"
                                   " node '%s'" % (instance.name, node_name),
                                   errors.ECODE_STATE)
    except errors.OpPrereqError, err:
      if self.op.ignore_consistency:
        self.proc.LogWarning(str(err.args[0]))
      else:
        raise

  def CheckPrereq(self):
    """Check prerequisites.

    """
    storage_type = self.op.storage_type

    if (constants.SO_FIX_CONSISTENCY not in
        constants.VALID_STORAGE_OPERATIONS.get(storage_type, [])):
      raise errors.OpPrereqError("Storage units of type '%s' can not be"
                                 " repaired" % storage_type,
                                 errors.ECODE_INVAL)

    # Check whether any instance on this node has faulty disks
    for inst in _GetNodeInstances(self.cfg, self.op.node_name):
      if not inst.admin_up:
        continue
      check_nodes = set(inst.all_nodes)
      check_nodes.discard(self.op.node_name)
      for inst_node_name in check_nodes:
        self._CheckFaultyDisks(inst, inst_node_name)

  def Exec(self, feedback_fn):
    feedback_fn("Repairing storage unit '%s' on %s ..." %
                (self.op.name, self.op.node_name))

    st_args = _GetStorageTypeArgs(self.cfg, self.op.storage_type)
    result = self.rpc.call_storage_execute(self.op.node_name,
                                           self.op.storage_type, st_args,
                                           self.op.name,
                                           constants.SO_FIX_CONSISTENCY)
    result.Raise("Failed to repair storage unit '%s' on %s" %
                 (self.op.name, self.op.node_name))


class LUNodeEvacuationStrategy(NoHooksLU):
  """Computes the node evacuation strategy.

  """
  _OP_REQP = ["nodes"]
  REQ_BGL = False

  def CheckArguments(self):
    if not hasattr(self.op, "remote_node"):
      self.op.remote_node = None
    if not hasattr(self.op, "iallocator"):
      self.op.iallocator = None
    if self.op.remote_node is not None and self.op.iallocator is not None:
      raise errors.OpPrereqError("Give either the iallocator or the new"
                                 " secondary, not both", errors.ECODE_INVAL)

  def ExpandNames(self):
    self.op.nodes = _GetWantedNodes(self, self.op.nodes)
    self.needed_locks = locks = {}
    if self.op.remote_node is None:
      locks[locking.LEVEL_NODE] = locking.ALL_SET
    else:
      self.op.remote_node = _ExpandNodeName(self.cfg, self.op.remote_node)
      locks[locking.LEVEL_NODE] = self.op.nodes + [self.op.remote_node]

  def CheckPrereq(self):
    pass

  def Exec(self, feedback_fn):
    if self.op.remote_node is not None:
      instances = []
      for node in self.op.nodes:
        instances.extend(_GetNodeSecondaryInstances(self.cfg, node))
      result = []
      for i in instances:
        if i.primary_node == self.op.remote_node:
          raise errors.OpPrereqError("Node %s is the primary node of"
                                     " instance %s, cannot use it as"
                                     " secondary" %
                                     (self.op.remote_node, i.name),
                                     errors.ECODE_INVAL)
        result.append([i.name, self.op.remote_node])
    else:
      ial = IAllocator(self.cfg, self.rpc,
                       mode=constants.IALLOCATOR_MODE_MEVAC,
                       evac_nodes=self.op.nodes)
      ial.Run(self.op.iallocator, validate=True)
      if not ial.success:
        raise errors.OpExecError("No valid evacuation solution: %s" % ial.info,
                                 errors.ECODE_NORES)
      result = ial.result
    return result


class LUGrowDisk(LogicalUnit):
  """Grow a disk of an instance.

  """
  HPATH = "disk-grow"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "disk", "amount", "wait_for_sync"]
  REQ_BGL = False

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "DISK": self.op.disk,
      "AMOUNT": self.op.amount,
      }
    env.update(_BuildInstanceHookEnvByObject(self, self.instance))
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance is in the cluster.

    """
    instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    assert instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    nodenames = list(instance.all_nodes)
    for node in nodenames:
      _CheckNodeOnline(self, node)


    self.instance = instance

    if instance.disk_template not in constants.DTS_GROWABLE:
      raise errors.OpPrereqError("Instance's disk layout does not support"
                                 " growing.", errors.ECODE_INVAL)

    self.disk = instance.FindDisk(self.op.disk)

    if instance.disk_template != constants.DT_FILE:
      # TODO: check the free disk space for file, when that feature will be
      # supported
      _CheckNodesFreeDisk(self, nodenames, self.op.amount)

  def Exec(self, feedback_fn):
    """Execute disk grow.

    """
    instance = self.instance
    disk = self.disk

    disks_ok, _ = _AssembleInstanceDisks(self, self.instance, disks=[disk])
    if not disks_ok:
      raise errors.OpExecError("Cannot activate block device to grow")

    for node in instance.all_nodes:
      self.cfg.SetDiskID(disk, node)
      result = self.rpc.call_blockdev_grow(node, disk, self.op.amount)
      result.Raise("Grow request failed to node %s" % node)

      # TODO: Rewrite code to work properly
      # DRBD goes into sync mode for a short amount of time after executing the
      # "resize" command. DRBD 8.x below version 8.0.13 contains a bug whereby
      # calling "resize" in sync mode fails. Sleeping for a short amount of
      # time is a work-around.
      time.sleep(5)

    disk.RecordGrow(self.op.amount)
    self.cfg.Update(instance, feedback_fn)
    if self.op.wait_for_sync:
      disk_abort = not _WaitForSync(self, instance, disks=[disk])
      if disk_abort:
        self.proc.LogWarning("Warning: disk sync-ing has not returned a good"
                             " status.\nPlease check the instance.")
      if not instance.admin_up:
        _SafeShutdownInstanceDisks(self, instance, disks=[disk])
    elif not instance.admin_up:
      self.proc.LogWarning("Not shutting down the disk even if the instance is"
                           " not supposed to be running because no wait for"
                           " sync mode was requested.")


class LUQueryInstanceData(NoHooksLU):
  """Query runtime instance data.

  """
  _OP_REQP = ["instances", "static"]
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {}
    self.share_locks = dict.fromkeys(locking.LEVELS, 1)

    if not isinstance(self.op.instances, list):
      raise errors.OpPrereqError("Invalid argument type 'instances'",
                                 errors.ECODE_INVAL)

    if self.op.instances:
      self.wanted_names = []
      for name in self.op.instances:
        full_name = _ExpandInstanceName(self.cfg, name)
        self.wanted_names.append(full_name)
      self.needed_locks[locking.LEVEL_INSTANCE] = self.wanted_names
    else:
      self.wanted_names = None
      self.needed_locks[locking.LEVEL_INSTANCE] = locking.ALL_SET

    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()

  def CheckPrereq(self):
    """Check prerequisites.

    This only checks the optional instance list against the existing names.

    """
    if self.wanted_names is None:
      self.wanted_names = self.acquired_locks[locking.LEVEL_INSTANCE]

    self.wanted_instances = [self.cfg.GetInstanceInfo(name) for name
                             in self.wanted_names]
    return

  def _ComputeBlockdevStatus(self, node, instance_name, dev):
    """Returns the status of a block device

    """
    if self.op.static or not node:
      return None

    self.cfg.SetDiskID(dev, node)

    result = self.rpc.call_blockdev_find(node, dev)
    if result.offline:
      return None

    result.Raise("Can't compute disk status for %s" % instance_name)

    status = result.payload
    if status is None:
      return None

    return (status.dev_path, status.major, status.minor,
            status.sync_percent, status.estimated_time,
            status.is_degraded, status.ldisk_status)

  def _ComputeDiskStatus(self, instance, snode, dev):
    """Compute block device status.

    """
    if dev.dev_type in constants.LDS_DRBD:
      # we change the snode then (otherwise we use the one passed in)
      if dev.logical_id[0] == instance.primary_node:
        snode = dev.logical_id[1]
      else:
        snode = dev.logical_id[0]

    dev_pstatus = self._ComputeBlockdevStatus(instance.primary_node,
                                              instance.name, dev)
    dev_sstatus = self._ComputeBlockdevStatus(snode, instance.name, dev)

    if dev.children:
      dev_children = [self._ComputeDiskStatus(instance, snode, child)
                      for child in dev.children]
    else:
      dev_children = []

    data = {
      "iv_name": dev.iv_name,
      "dev_type": dev.dev_type,
      "logical_id": dev.logical_id,
      "physical_id": dev.physical_id,
      "pstatus": dev_pstatus,
      "sstatus": dev_sstatus,
      "children": dev_children,
      "mode": dev.mode,
      "size": dev.size,
      }

    return data

  def Exec(self, feedback_fn):
    """Gather and return data"""
    result = {}

    cluster = self.cfg.GetClusterInfo()

    for instance in self.wanted_instances:
      if not self.op.static:
        remote_info = self.rpc.call_instance_info(instance.primary_node,
                                                  instance.name,
                                                  instance.hypervisor)
        remote_info.Raise("Error checking node %s" % instance.primary_node)
        remote_info = remote_info.payload
        if remote_info and "state" in remote_info:
          remote_state = "up"
        else:
          remote_state = "down"
      else:
        remote_state = None
      if instance.admin_up:
        config_state = "up"
      else:
        config_state = "down"

      disks = [self._ComputeDiskStatus(instance, None, device)
               for device in instance.disks]

      idict = {
        "name": instance.name,
        "config_state": config_state,
        "run_state": remote_state,
        "pnode": instance.primary_node,
        "snodes": instance.secondary_nodes,
        "os": instance.os,
        # this happens to be the same format used for hooks
        "nics": _NICListToTuple(self, instance.nics),
        "disk_template": instance.disk_template,
        "disks": disks,
        "hypervisor": instance.hypervisor,
        "network_port": instance.network_port,
        "hv_instance": instance.hvparams,
        "hv_actual": cluster.FillHV(instance, skip_globals=True),
        "be_instance": instance.beparams,
        "be_actual": cluster.FillBE(instance),
        "serial_no": instance.serial_no,
        "mtime": instance.mtime,
        "ctime": instance.ctime,
        "uuid": instance.uuid,
        }

      result[instance.name] = idict

    return result


class LUSetInstanceParams(LogicalUnit):
  """Modifies an instances's parameters.

  """
  HPATH = "instance-modify"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def CheckArguments(self):
    if not hasattr(self.op, 'nics'):
      self.op.nics = []
    if not hasattr(self.op, 'disks'):
      self.op.disks = []
    if not hasattr(self.op, 'beparams'):
      self.op.beparams = {}
    if not hasattr(self.op, 'hvparams'):
      self.op.hvparams = {}
    if not hasattr(self.op, "disk_template"):
      self.op.disk_template = None
    if not hasattr(self.op, "remote_node"):
      self.op.remote_node = None
    if not hasattr(self.op, "os_name"):
      self.op.os_name = None
    if not hasattr(self.op, "force_variant"):
      self.op.force_variant = False
    self.op.force = getattr(self.op, "force", False)
    if not (self.op.nics or self.op.disks or self.op.disk_template or
            self.op.hvparams or self.op.beparams or self.op.os_name):
      raise errors.OpPrereqError("No changes submitted", errors.ECODE_INVAL)

    if self.op.hvparams:
      _CheckGlobalHvParams(self.op.hvparams)

    # Disk validation
    disk_addremove = 0
    for disk_op, disk_dict in self.op.disks:
      utils.ForceDictType(disk_dict, constants.IDISK_PARAMS_TYPES)
      if disk_op == constants.DDM_REMOVE:
        disk_addremove += 1
        continue
      elif disk_op == constants.DDM_ADD:
        disk_addremove += 1
      else:
        if not isinstance(disk_op, int):
          raise errors.OpPrereqError("Invalid disk index", errors.ECODE_INVAL)
        if not isinstance(disk_dict, dict):
          msg = "Invalid disk value: expected dict, got '%s'" % disk_dict
          raise errors.OpPrereqError(msg, errors.ECODE_INVAL)

      if disk_op == constants.DDM_ADD:
        mode = disk_dict.setdefault('mode', constants.DISK_RDWR)
        if mode not in constants.DISK_ACCESS_SET:
          raise errors.OpPrereqError("Invalid disk access mode '%s'" % mode,
                                     errors.ECODE_INVAL)
        size = disk_dict.get('size', None)
        if size is None:
          raise errors.OpPrereqError("Required disk parameter size missing",
                                     errors.ECODE_INVAL)
        try:
          size = int(size)
        except (TypeError, ValueError), err:
          raise errors.OpPrereqError("Invalid disk size parameter: %s" %
                                     str(err), errors.ECODE_INVAL)
        disk_dict['size'] = size
      else:
        # modification of disk
        if 'size' in disk_dict:
          raise errors.OpPrereqError("Disk size change not possible, use"
                                     " grow-disk", errors.ECODE_INVAL)

    if disk_addremove > 1:
      raise errors.OpPrereqError("Only one disk add or remove operation"
                                 " supported at a time", errors.ECODE_INVAL)

    if self.op.disks and self.op.disk_template is not None:
      raise errors.OpPrereqError("Disk template conversion and other disk"
                                 " changes not supported at the same time",
                                 errors.ECODE_INVAL)

    if self.op.disk_template:
      _CheckDiskTemplate(self.op.disk_template)
      if (self.op.disk_template in constants.DTS_NET_MIRROR and
          self.op.remote_node is None):
        raise errors.OpPrereqError("Changing the disk template to a mirrored"
                                   " one requires specifying a secondary node",
                                   errors.ECODE_INVAL)

    # NIC validation
    nic_addremove = 0
    for nic_op, nic_dict in self.op.nics:
      utils.ForceDictType(nic_dict, constants.INIC_PARAMS_TYPES)
      if nic_op == constants.DDM_REMOVE:
        nic_addremove += 1
        continue
      elif nic_op == constants.DDM_ADD:
        nic_addremove += 1
      else:
        if not isinstance(nic_op, int):
          raise errors.OpPrereqError("Invalid nic index", errors.ECODE_INVAL)
        if not isinstance(nic_dict, dict):
          msg = "Invalid nic value: expected dict, got '%s'" % nic_dict
          raise errors.OpPrereqError(msg, errors.ECODE_INVAL)

      # nic_dict should be a dict
      nic_ip = nic_dict.get('ip', None)
      if nic_ip is not None:
        if nic_ip.lower() == constants.VALUE_NONE:
          nic_dict['ip'] = None
        else:
          if not utils.IsValidIP(nic_ip):
            raise errors.OpPrereqError("Invalid IP address '%s'" % nic_ip,
                                       errors.ECODE_INVAL)

      nic_bridge = nic_dict.get('bridge', None)
      nic_link = nic_dict.get('link', None)
      if nic_bridge and nic_link:
        raise errors.OpPrereqError("Cannot pass 'bridge' and 'link'"
                                   " at the same time", errors.ECODE_INVAL)
      elif nic_bridge and nic_bridge.lower() == constants.VALUE_NONE:
        nic_dict['bridge'] = None
      elif nic_link and nic_link.lower() == constants.VALUE_NONE:
        nic_dict['link'] = None

      if nic_op == constants.DDM_ADD:
        nic_mac = nic_dict.get('mac', None)
        if nic_mac is None:
          nic_dict['mac'] = constants.VALUE_AUTO

      if 'mac' in nic_dict:
        nic_mac = nic_dict['mac']
        if nic_mac not in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
          nic_mac = utils.NormalizeAndValidateMac(nic_mac)

        if nic_op != constants.DDM_ADD and nic_mac == constants.VALUE_AUTO:
          raise errors.OpPrereqError("'auto' is not a valid MAC address when"
                                     " modifying an existing nic",
                                     errors.ECODE_INVAL)

    if nic_addremove > 1:
      raise errors.OpPrereqError("Only one NIC add or remove operation"
                                 " supported at a time", errors.ECODE_INVAL)

  def ExpandNames(self):
    self._ExpandAndLockInstance()
    self.needed_locks[locking.LEVEL_NODE] = []
    self.recalculate_locks[locking.LEVEL_NODE] = constants.LOCKS_REPLACE

  def DeclareLocks(self, level):
    if level == locking.LEVEL_NODE:
      self._LockInstancesNodes()
      if self.op.disk_template and self.op.remote_node:
        self.op.remote_node = _ExpandNodeName(self.cfg, self.op.remote_node)
        self.needed_locks[locking.LEVEL_NODE].append(self.op.remote_node)

  def BuildHooksEnv(self):
    """Build hooks env.

    This runs on the master, primary and secondaries.

    """
    args = dict()
    if constants.BE_MEMORY in self.be_new:
      args['memory'] = self.be_new[constants.BE_MEMORY]
    if constants.BE_VCPUS in self.be_new:
      args['vcpus'] = self.be_new[constants.BE_VCPUS]
    # TODO: export disk changes. Note: _BuildInstanceHookEnv* don't export disk
    # information at all.
    if self.op.nics:
      args['nics'] = []
      nic_override = dict(self.op.nics)
      for idx, nic in enumerate(self.instance.nics):
        if idx in nic_override:
          this_nic_override = nic_override[idx]
        else:
          this_nic_override = {}
        if 'ip' in this_nic_override:
          ip = this_nic_override['ip']
        else:
          ip = nic.ip
        if 'mac' in this_nic_override:
          mac = this_nic_override['mac']
        else:
          mac = nic.mac
        if idx in self.nic_pnew:
          nicparams = self.nic_pnew[idx]
        else:
          nicparams = self.cluster.SimpleFillNIC(nic.nicparams)
        mode = nicparams[constants.NIC_MODE]
        link = nicparams[constants.NIC_LINK]
        args['nics'].append((ip, mac, mode, link))
      if constants.DDM_ADD in nic_override:
        ip = nic_override[constants.DDM_ADD].get('ip', None)
        mac = nic_override[constants.DDM_ADD]['mac']
        nicparams = self.nic_pnew[constants.DDM_ADD]
        mode = nicparams[constants.NIC_MODE]
        link = nicparams[constants.NIC_LINK]
        args['nics'].append((ip, mac, mode, link))
      elif constants.DDM_REMOVE in nic_override:
        del args['nics'][-1]

    env = _BuildInstanceHookEnvByObject(self, self.instance, override=args)
    if self.op.disk_template:
      env["NEW_DISK_TEMPLATE"] = self.op.disk_template
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This only checks the instance list against the existing names.

    """
    self.force = self.op.force

    # checking the new params on the primary/secondary nodes

    instance = self.instance = self.cfg.GetInstanceInfo(self.op.instance_name)
    cluster = self.cluster = self.cfg.GetClusterInfo()
    assert self.instance is not None, \
      "Cannot retrieve locked instance %s" % self.op.instance_name
    pnode = instance.primary_node
    nodelist = list(instance.all_nodes)

    if self.op.disk_template:
      if instance.disk_template == self.op.disk_template:
        raise errors.OpPrereqError("Instance already has disk template %s" %
                                   instance.disk_template, errors.ECODE_INVAL)

      if (instance.disk_template,
          self.op.disk_template) not in self._DISK_CONVERSIONS:
        raise errors.OpPrereqError("Unsupported disk template conversion from"
                                   " %s to %s" % (instance.disk_template,
                                                  self.op.disk_template),
                                   errors.ECODE_INVAL)
      if self.op.disk_template in constants.DTS_NET_MIRROR:
        _CheckNodeOnline(self, self.op.remote_node)
        _CheckNodeNotDrained(self, self.op.remote_node)
        disks = [{"size": d.size} for d in instance.disks]
        required = _ComputeDiskSize(self.op.disk_template, disks)
        _CheckNodesFreeDisk(self, [self.op.remote_node], required)
        _CheckInstanceDown(self, instance, "cannot change disk template")

    # hvparams processing
    if self.op.hvparams:
      hv_type = instance.hypervisor
      i_hvdict = _GetUpdatedParams(instance.hvparams, self.op.hvparams)
      utils.ForceDictType(i_hvdict, constants.HVS_PARAMETER_TYPES)
      hv_new = cluster.SimpleFillHV(hv_type, instance.os, i_hvdict)

      # local check
      hypervisor.GetHypervisor(hv_type).CheckParameterSyntax(hv_new)
      _CheckHVParams(self, nodelist, instance.hypervisor, hv_new)
      self.hv_new = hv_new # the new actual values
      self.hv_inst = i_hvdict # the new dict (without defaults)
    else:
      self.hv_new = self.hv_inst = {}

    # beparams processing
    if self.op.beparams:
      i_bedict = _GetUpdatedParams(instance.beparams, self.op.beparams)
      utils.ForceDictType(i_bedict, constants.BES_PARAMETER_TYPES)
      be_new = cluster.SimpleFillBE(i_bedict)
      self.be_new = be_new # the new actual values
      self.be_inst = i_bedict # the new dict (without defaults)
    else:
      self.be_new = self.be_inst = {}

    self.warn = []

    if constants.BE_MEMORY in self.op.beparams and not self.force:
      mem_check_list = [pnode]
      if be_new[constants.BE_AUTO_BALANCE]:
        # either we changed auto_balance to yes or it was from before
        mem_check_list.extend(instance.secondary_nodes)
      instance_info = self.rpc.call_instance_info(pnode, instance.name,
                                                  instance.hypervisor)
      nodeinfo = self.rpc.call_node_info(mem_check_list, self.cfg.GetVGName(),
                                         instance.hypervisor)
      pninfo = nodeinfo[pnode]
      msg = pninfo.fail_msg
      if msg:
        # Assume the primary node is unreachable and go ahead
        self.warn.append("Can't get info from primary node %s: %s" %
                         (pnode,  msg))
      elif not isinstance(pninfo.payload.get('memory_free', None), int):
        self.warn.append("Node data from primary node %s doesn't contain"
                         " free memory information" % pnode)
      elif instance_info.fail_msg:
        self.warn.append("Can't get instance runtime information: %s" %
                        instance_info.fail_msg)
      else:
        if instance_info.payload:
          current_mem = int(instance_info.payload['memory'])
        else:
          # Assume instance not running
          # (there is a slight race condition here, but it's not very probable,
          # and we have no other way to check)
          current_mem = 0
        miss_mem = (be_new[constants.BE_MEMORY] - current_mem -
                    pninfo.payload['memory_free'])
        if miss_mem > 0:
          raise errors.OpPrereqError("This change will prevent the instance"
                                     " from starting, due to %d MB of memory"
                                     " missing on its primary node" % miss_mem,
                                     errors.ECODE_NORES)

      if be_new[constants.BE_AUTO_BALANCE]:
        for node, nres in nodeinfo.items():
          if node not in instance.secondary_nodes:
            continue
          msg = nres.fail_msg
          if msg:
            self.warn.append("Can't get info from secondary node %s: %s" %
                             (node, msg))
          elif not isinstance(nres.payload.get('memory_free', None), int):
            self.warn.append("Secondary node %s didn't return free"
                             " memory information" % node)
          elif be_new[constants.BE_MEMORY] > nres.payload['memory_free']:
            self.warn.append("Not enough memory to failover instance to"
                             " secondary node %s" % node)

    # NIC processing
    self.nic_pnew = {}
    self.nic_pinst = {}
    for nic_op, nic_dict in self.op.nics:
      if nic_op == constants.DDM_REMOVE:
        if not instance.nics:
          raise errors.OpPrereqError("Instance has no NICs, cannot remove",
                                     errors.ECODE_INVAL)
        continue
      if nic_op != constants.DDM_ADD:
        # an existing nic
        if not instance.nics:
          raise errors.OpPrereqError("Invalid NIC index %s, instance has"
                                     " no NICs" % nic_op,
                                     errors.ECODE_INVAL)
        if nic_op < 0 or nic_op >= len(instance.nics):
          raise errors.OpPrereqError("Invalid NIC index %s, valid values"
                                     " are 0 to %d" %
                                     (nic_op, len(instance.nics) - 1),
                                     errors.ECODE_INVAL)
        old_nic_params = instance.nics[nic_op].nicparams
        old_nic_ip = instance.nics[nic_op].ip
      else:
        old_nic_params = {}
        old_nic_ip = None

      update_params_dict = dict([(key, nic_dict[key])
                                 for key in constants.NICS_PARAMETERS
                                 if key in nic_dict])

      if 'bridge' in nic_dict:
        update_params_dict[constants.NIC_LINK] = nic_dict['bridge']

      new_nic_params = _GetUpdatedParams(old_nic_params,
                                         update_params_dict)
      utils.ForceDictType(new_nic_params, constants.NICS_PARAMETER_TYPES)
      new_filled_nic_params = cluster.SimpleFillNIC(new_nic_params)
      objects.NIC.CheckParameterSyntax(new_filled_nic_params)
      self.nic_pinst[nic_op] = new_nic_params
      self.nic_pnew[nic_op] = new_filled_nic_params
      new_nic_mode = new_filled_nic_params[constants.NIC_MODE]

      if new_nic_mode == constants.NIC_MODE_BRIDGED:
        nic_bridge = new_filled_nic_params[constants.NIC_LINK]
        msg = self.rpc.call_bridges_exist(pnode, [nic_bridge]).fail_msg
        if msg:
          msg = "Error checking bridges on node %s: %s" % (pnode, msg)
          if self.force:
            self.warn.append(msg)
          else:
            raise errors.OpPrereqError(msg, errors.ECODE_ENVIRON)
      if new_nic_mode == constants.NIC_MODE_ROUTED:
        if 'ip' in nic_dict:
          nic_ip = nic_dict['ip']
        else:
          nic_ip = old_nic_ip
        if nic_ip is None:
          raise errors.OpPrereqError('Cannot set the nic ip to None'
                                     ' on a routed nic', errors.ECODE_INVAL)
      if 'mac' in nic_dict:
        nic_mac = nic_dict['mac']
        if nic_mac is None:
          raise errors.OpPrereqError('Cannot set the nic mac to None',
                                     errors.ECODE_INVAL)
        elif nic_mac in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
          # otherwise generate the mac
          nic_dict['mac'] = self.cfg.GenerateMAC(self.proc.GetECId())
        else:
          # or validate/reserve the current one
          try:
            self.cfg.ReserveMAC(nic_mac, self.proc.GetECId())
          except errors.ReservationError:
            raise errors.OpPrereqError("MAC address %s already in use"
                                       " in cluster" % nic_mac,
                                       errors.ECODE_NOTUNIQUE)

    # DISK processing
    if self.op.disks and instance.disk_template == constants.DT_DISKLESS:
      raise errors.OpPrereqError("Disk operations not supported for"
                                 " diskless instances",
                                 errors.ECODE_INVAL)
    for disk_op, _ in self.op.disks:
      if disk_op == constants.DDM_REMOVE:
        if len(instance.disks) == 1:
          raise errors.OpPrereqError("Cannot remove the last disk of"
                                     " an instance", errors.ECODE_INVAL)
        _CheckInstanceDown(self, instance, "cannot remove disks")

      if (disk_op == constants.DDM_ADD and
          len(instance.nics) >= constants.MAX_DISKS):
        raise errors.OpPrereqError("Instance has too many disks (%d), cannot"
                                   " add more" % constants.MAX_DISKS,
                                   errors.ECODE_STATE)
      if disk_op not in (constants.DDM_ADD, constants.DDM_REMOVE):
        # an existing disk
        if disk_op < 0 or disk_op >= len(instance.disks):
          raise errors.OpPrereqError("Invalid disk index %s, valid values"
                                     " are 0 to %d" %
                                     (disk_op, len(instance.disks)),
                                     errors.ECODE_INVAL)

    # OS change
    if self.op.os_name and not self.op.force:
      _CheckNodeHasOS(self, instance.primary_node, self.op.os_name,
                      self.op.force_variant)

    return

  def _ConvertPlainToDrbd(self, feedback_fn):
    """Converts an instance from plain to drbd.

    """
    feedback_fn("Converting template to drbd")
    instance = self.instance
    pnode = instance.primary_node
    snode = self.op.remote_node

    # create a fake disk info for _GenerateDiskTemplate
    disk_info = [{"size": d.size, "mode": d.mode} for d in instance.disks]
    new_disks = _GenerateDiskTemplate(self, self.op.disk_template,
                                      instance.name, pnode, [snode],
                                      disk_info, None, None, 0)
    info = _GetInstanceInfoText(instance)
    feedback_fn("Creating aditional volumes...")
    # first, create the missing data and meta devices
    for disk in new_disks:
      # unfortunately this is... not too nice
      _CreateSingleBlockDev(self, pnode, instance, disk.children[1],
                            info, True)
      for child in disk.children:
        _CreateSingleBlockDev(self, snode, instance, child, info, True)
    # at this stage, all new LVs have been created, we can rename the
    # old ones
    feedback_fn("Renaming original volumes...")
    rename_list = [(o, n.children[0].logical_id)
                   for (o, n) in zip(instance.disks, new_disks)]
    result = self.rpc.call_blockdev_rename(pnode, rename_list)
    result.Raise("Failed to rename original LVs")

    feedback_fn("Initializing DRBD devices...")
    # all child devices are in place, we can now create the DRBD devices
    for disk in new_disks:
      for node in [pnode, snode]:
        f_create = node == pnode
        _CreateSingleBlockDev(self, node, instance, disk, info, f_create)

    # at this point, the instance has been modified
    instance.disk_template = constants.DT_DRBD8
    instance.disks = new_disks
    self.cfg.Update(instance, feedback_fn)

    # disks are created, waiting for sync
    disk_abort = not _WaitForSync(self, instance)
    if disk_abort:
      raise errors.OpExecError("There are some degraded disks for"
                               " this instance, please cleanup manually")

  def _ConvertDrbdToPlain(self, feedback_fn):
    """Converts an instance from drbd to plain.

    """
    instance = self.instance
    assert len(instance.secondary_nodes) == 1
    pnode = instance.primary_node
    snode = instance.secondary_nodes[0]
    feedback_fn("Converting template to plain")

    old_disks = instance.disks
    new_disks = [d.children[0] for d in old_disks]

    # copy over size and mode
    for parent, child in zip(old_disks, new_disks):
      child.size = parent.size
      child.mode = parent.mode

    # update instance structure
    instance.disks = new_disks
    instance.disk_template = constants.DT_PLAIN
    self.cfg.Update(instance, feedback_fn)

    feedback_fn("Removing volumes on the secondary node...")
    for disk in old_disks:
      self.cfg.SetDiskID(disk, snode)
      msg = self.rpc.call_blockdev_remove(snode, disk).fail_msg
      if msg:
        self.LogWarning("Could not remove block device %s on node %s,"
                        " continuing anyway: %s", disk.iv_name, snode, msg)

    feedback_fn("Removing unneeded volumes on the primary node...")
    for idx, disk in enumerate(old_disks):
      meta = disk.children[1]
      self.cfg.SetDiskID(meta, pnode)
      msg = self.rpc.call_blockdev_remove(pnode, meta).fail_msg
      if msg:
        self.LogWarning("Could not remove metadata for disk %d on node %s,"
                        " continuing anyway: %s", idx, pnode, msg)


  def Exec(self, feedback_fn):
    """Modifies an instance.

    All parameters take effect only at the next restart of the instance.

    """
    # Process here the warnings from CheckPrereq, as we don't have a
    # feedback_fn there.
    for warn in self.warn:
      feedback_fn("WARNING: %s" % warn)

    result = []
    instance = self.instance
    # disk changes
    for disk_op, disk_dict in self.op.disks:
      if disk_op == constants.DDM_REMOVE:
        # remove the last disk
        device = instance.disks.pop()
        device_idx = len(instance.disks)
        for node, disk in device.ComputeNodeTree(instance.primary_node):
          self.cfg.SetDiskID(disk, node)
          msg = self.rpc.call_blockdev_remove(node, disk).fail_msg
          if msg:
            self.LogWarning("Could not remove disk/%d on node %s: %s,"
                            " continuing anyway", device_idx, node, msg)
        result.append(("disk/%d" % device_idx, "remove"))
      elif disk_op == constants.DDM_ADD:
        # add a new disk
        if instance.disk_template == constants.DT_FILE:
          file_driver, file_path = instance.disks[0].logical_id
          file_path = os.path.dirname(file_path)
        else:
          file_driver = file_path = None
        disk_idx_base = len(instance.disks)
        new_disk = _GenerateDiskTemplate(self,
                                         instance.disk_template,
                                         instance.name, instance.primary_node,
                                         instance.secondary_nodes,
                                         [disk_dict],
                                         file_path,
                                         file_driver,
                                         disk_idx_base)[0]
        instance.disks.append(new_disk)
        info = _GetInstanceInfoText(instance)

        logging.info("Creating volume %s for instance %s",
                     new_disk.iv_name, instance.name)
        # Note: this needs to be kept in sync with _CreateDisks
        #HARDCODE
        for node in instance.all_nodes:
          f_create = node == instance.primary_node
          try:
            _CreateBlockDev(self, node, instance, new_disk,
                            f_create, info, f_create)
          except errors.OpExecError, err:
            self.LogWarning("Failed to create volume %s (%s) on"
                            " node %s: %s",
                            new_disk.iv_name, new_disk, node, err)
        result.append(("disk/%d" % disk_idx_base, "add:size=%s,mode=%s" %
                       (new_disk.size, new_disk.mode)))
      else:
        # change a given disk
        instance.disks[disk_op].mode = disk_dict['mode']
        result.append(("disk.mode/%d" % disk_op, disk_dict['mode']))

    if self.op.disk_template:
      r_shut = _ShutdownInstanceDisks(self, instance)
      if not r_shut:
        raise errors.OpExecError("Cannot shutdow instance disks, unable to"
                                 " proceed with disk template conversion")
      mode = (instance.disk_template, self.op.disk_template)
      try:
        self._DISK_CONVERSIONS[mode](self, feedback_fn)
      except:
        self.cfg.ReleaseDRBDMinors(instance.name)
        raise
      result.append(("disk_template", self.op.disk_template))

    # NIC changes
    for nic_op, nic_dict in self.op.nics:
      if nic_op == constants.DDM_REMOVE:
        # remove the last nic
        del instance.nics[-1]
        result.append(("nic.%d" % len(instance.nics), "remove"))
      elif nic_op == constants.DDM_ADD:
        # mac and bridge should be set, by now
        mac = nic_dict['mac']
        ip = nic_dict.get('ip', None)
        nicparams = self.nic_pinst[constants.DDM_ADD]
        new_nic = objects.NIC(mac=mac, ip=ip, nicparams=nicparams)
        instance.nics.append(new_nic)
        result.append(("nic.%d" % (len(instance.nics) - 1),
                       "add:mac=%s,ip=%s,mode=%s,link=%s" %
                       (new_nic.mac, new_nic.ip,
                        self.nic_pnew[constants.DDM_ADD][constants.NIC_MODE],
                        self.nic_pnew[constants.DDM_ADD][constants.NIC_LINK]
                       )))
      else:
        for key in 'mac', 'ip':
          if key in nic_dict:
            setattr(instance.nics[nic_op], key, nic_dict[key])
        if nic_op in self.nic_pinst:
          instance.nics[nic_op].nicparams = self.nic_pinst[nic_op]
        for key, val in nic_dict.iteritems():
          result.append(("nic.%s/%d" % (key, nic_op), val))

    # hvparams changes
    if self.op.hvparams:
      instance.hvparams = self.hv_inst
      for key, val in self.op.hvparams.iteritems():
        result.append(("hv/%s" % key, val))

    # beparams changes
    if self.op.beparams:
      instance.beparams = self.be_inst
      for key, val in self.op.beparams.iteritems():
        result.append(("be/%s" % key, val))

    # OS change
    if self.op.os_name:
      instance.os = self.op.os_name

    self.cfg.Update(instance, feedback_fn)

    return result

  _DISK_CONVERSIONS = {
    (constants.DT_PLAIN, constants.DT_DRBD8): _ConvertPlainToDrbd,
    (constants.DT_DRBD8, constants.DT_PLAIN): _ConvertDrbdToPlain,
    }


class LUQueryExports(NoHooksLU):
  """Query the exports list

  """
  _OP_REQP = ['nodes']
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1
    if not self.op.nodes:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET
    else:
      self.needed_locks[locking.LEVEL_NODE] = \
        _GetWantedNodes(self, self.op.nodes)

  def CheckPrereq(self):
    """Check prerequisites.

    """
    self.nodes = self.acquired_locks[locking.LEVEL_NODE]

  def Exec(self, feedback_fn):
    """Compute the list of all the exported system images.

    @rtype: dict
    @return: a dictionary with the structure node->(export-list)
        where export-list is a list of the instances exported on
        that node.

    """
    rpcresult = self.rpc.call_export_list(self.nodes)
    result = {}
    for node in rpcresult:
      if rpcresult[node].fail_msg:
        result[node] = False
      else:
        result[node] = rpcresult[node].payload

    return result


class LUPrepareExport(NoHooksLU):
  """Prepares an instance for an export and returns useful information.

  """
  _OP_REQP = ["instance_name", "mode"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    if self.op.mode not in constants.EXPORT_MODES:
      raise errors.OpPrereqError("Invalid export mode %r" % self.op.mode,
                                 errors.ECODE_INVAL)

  def ExpandNames(self):
    self._ExpandAndLockInstance()

  def CheckPrereq(self):
    """Check prerequisites.

    """
    instance_name = self.op.instance_name

    self.instance = self.cfg.GetInstanceInfo(instance_name)
    assert self.instance is not None, \
          "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, self.instance.primary_node)

    self._cds = _GetClusterDomainSecret()

  def Exec(self, feedback_fn):
    """Prepares an instance for an export.

    """
    instance = self.instance

    if self.op.mode == constants.EXPORT_MODE_REMOTE:
      salt = utils.GenerateSecret(8)

      feedback_fn("Generating X509 certificate on %s" % instance.primary_node)
      result = self.rpc.call_x509_cert_create(instance.primary_node,
                                              constants.RIE_CERT_VALIDITY)
      result.Raise("Can't create X509 key and certificate on %s" % result.node)

      (name, cert_pem) = result.payload

      cert = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM,
                                             cert_pem)

      return {
        "handshake": masterd.instance.ComputeRemoteExportHandshake(self._cds),
        "x509_key_name": (name, utils.Sha1Hmac(self._cds, name, salt=salt),
                          salt),
        "x509_ca": utils.SignX509Certificate(cert, self._cds, salt),
        }

    return None


class LUExportInstance(LogicalUnit):
  """Export an instance to an image in the cluster.

  """
  HPATH = "instance-export"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "target_node", "shutdown"]
  REQ_BGL = False

  def CheckArguments(self):
    """Check the arguments.

    """
    _CheckBooleanOpField(self.op, "remove_instance")
    _CheckBooleanOpField(self.op, "ignore_remove_failures")

    self.shutdown_timeout = getattr(self.op, "shutdown_timeout",
                                    constants.DEFAULT_SHUTDOWN_TIMEOUT)
    self.remove_instance = getattr(self.op, "remove_instance", False)
    self.ignore_remove_failures = getattr(self.op, "ignore_remove_failures",
                                          False)
    self.export_mode = getattr(self.op, "mode", constants.EXPORT_MODE_LOCAL)
    self.x509_key_name = getattr(self.op, "x509_key_name", None)
    self.dest_x509_ca_pem = getattr(self.op, "destination_x509_ca", None)

    if self.remove_instance and not self.op.shutdown:
      raise errors.OpPrereqError("Can not remove instance without shutting it"
                                 " down before")

    if self.export_mode not in constants.EXPORT_MODES:
      raise errors.OpPrereqError("Invalid export mode %r" % self.export_mode,
                                 errors.ECODE_INVAL)

    if self.export_mode == constants.EXPORT_MODE_REMOTE:
      if not self.x509_key_name:
        raise errors.OpPrereqError("Missing X509 key name for encryption",
                                   errors.ECODE_INVAL)

      if not self.dest_x509_ca_pem:
        raise errors.OpPrereqError("Missing destination X509 CA",
                                   errors.ECODE_INVAL)

  def ExpandNames(self):
    self._ExpandAndLockInstance()

    # Lock all nodes for local exports
    if self.export_mode == constants.EXPORT_MODE_LOCAL:
      # FIXME: lock only instance primary and destination node
      #
      # Sad but true, for now we have do lock all nodes, as we don't know where
      # the previous export might be, and in this LU we search for it and
      # remove it from its current node. In the future we could fix this by:
      #  - making a tasklet to search (share-lock all), then create the new one,
      #    then one to remove, after
      #  - removing the removal operation altogether
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

  def DeclareLocks(self, level):
    """Last minute lock declaration."""
    # All nodes are locked anyway, so nothing to do here.

  def BuildHooksEnv(self):
    """Build hooks env.

    This will run on the master, primary node and target node.

    """
    env = {
      "EXPORT_MODE": self.export_mode,
      "EXPORT_NODE": self.op.target_node,
      "EXPORT_DO_SHUTDOWN": self.op.shutdown,
      "SHUTDOWN_TIMEOUT": self.shutdown_timeout,
      # TODO: Generic function for boolean env variables
      "REMOVE_INSTANCE": str(bool(self.remove_instance)),
      }

    env.update(_BuildInstanceHookEnvByObject(self, self.instance))

    nl = [self.cfg.GetMasterNode(), self.instance.primary_node]

    if self.export_mode == constants.EXPORT_MODE_LOCAL:
      nl.append(self.op.target_node)

    return env, nl, nl

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that the instance and node names are valid.

    """
    instance_name = self.op.instance_name

    self.instance = self.cfg.GetInstanceInfo(instance_name)
    assert self.instance is not None, \
          "Cannot retrieve locked instance %s" % self.op.instance_name
    _CheckNodeOnline(self, self.instance.primary_node)

    if self.export_mode == constants.EXPORT_MODE_LOCAL:
      self.op.target_node = _ExpandNodeName(self.cfg, self.op.target_node)
      self.dst_node = self.cfg.GetNodeInfo(self.op.target_node)
      assert self.dst_node is not None

      _CheckNodeOnline(self, self.dst_node.name)
      _CheckNodeNotDrained(self, self.dst_node.name)

      self._cds = None
      self.dest_disk_info = None
      self.dest_x509_ca = None

    elif self.export_mode == constants.EXPORT_MODE_REMOTE:
      self.dst_node = None

      if len(self.op.target_node) != len(self.instance.disks):
        raise errors.OpPrereqError(("Received destination information for %s"
                                    " disks, but instance %s has %s disks") %
                                   (len(self.op.target_node), instance_name,
                                    len(self.instance.disks)),
                                   errors.ECODE_INVAL)

      cds = _GetClusterDomainSecret()

      # Check X509 key name
      try:
        (key_name, hmac_digest, hmac_salt) = self.x509_key_name
      except (TypeError, ValueError), err:
        raise errors.OpPrereqError("Invalid data for X509 key name: %s" % err)

      if not utils.VerifySha1Hmac(cds, key_name, hmac_digest, salt=hmac_salt):
        raise errors.OpPrereqError("HMAC for X509 key name is wrong",
                                   errors.ECODE_INVAL)

      # Load and verify CA
      try:
        (cert, _) = utils.LoadSignedX509Certificate(self.dest_x509_ca_pem, cds)
      except OpenSSL.crypto.Error, err:
        raise errors.OpPrereqError("Unable to load destination X509 CA (%s)" %
                                   (err, ), errors.ECODE_INVAL)

      (errcode, msg) = utils.VerifyX509Certificate(cert, None, None)
      if errcode is not None:
        raise errors.OpPrereqError("Invalid destination X509 CA (%s)" % (msg, ),
                                   errors.ECODE_INVAL)

      self.dest_x509_ca = cert

      # Verify target information
      disk_info = []
      for idx, disk_data in enumerate(self.op.target_node):
        try:
          (host, port, magic) = \
            masterd.instance.CheckRemoteExportDiskInfo(cds, idx, disk_data)
        except errors.GenericError, err:
          raise errors.OpPrereqError("Target info for disk %s: %s" % (idx, err),
                                     errors.ECODE_INVAL)

        disk_info.append((host, port, magic))

      assert len(disk_info) == len(self.op.target_node)
      self.dest_disk_info = disk_info

    else:
      raise errors.ProgrammerError("Unhandled export mode %r" %
                                   self.export_mode)

    # instance disk type verification
    # TODO: Implement export support for file-based disks
    for disk in self.instance.disks:
      if disk.dev_type == constants.LD_FILE:
        raise errors.OpPrereqError("Export not supported for instances with"
                                   " file-based disks", errors.ECODE_INVAL)

  def _CleanupExports(self, feedback_fn):
    """Removes exports of current instance from all other nodes.

    If an instance in a cluster with nodes A..D was exported to node C, its
    exports will be removed from the nodes A, B and D.

    """
    assert self.export_mode != constants.EXPORT_MODE_REMOTE

    nodelist = self.cfg.GetNodeList()
    nodelist.remove(self.dst_node.name)

    # on one-node clusters nodelist will be empty after the removal
    # if we proceed the backup would be removed because OpQueryExports
    # substitutes an empty list with the full cluster node list.
    iname = self.instance.name
    if nodelist:
      feedback_fn("Removing old exports for instance %s" % iname)
      exportlist = self.rpc.call_export_list(nodelist)
      for node in exportlist:
        if exportlist[node].fail_msg:
          continue
        if iname in exportlist[node].payload:
          msg = self.rpc.call_export_remove(node, iname).fail_msg
          if msg:
            self.LogWarning("Could not remove older export for instance %s"
                            " on node %s: %s", iname, node, msg)

  def Exec(self, feedback_fn):
    """Export an instance to an image in the cluster.

    """
    assert self.export_mode in constants.EXPORT_MODES

    instance = self.instance
    src_node = instance.primary_node

    if self.op.shutdown:
      # shutdown the instance, but not the disks
      feedback_fn("Shutting down instance %s" % instance.name)
      result = self.rpc.call_instance_shutdown(src_node, instance,
                                               self.shutdown_timeout)
      # TODO: Maybe ignore failures if ignore_remove_failures is set
      result.Raise("Could not shutdown instance %s on"
                   " node %s" % (instance.name, src_node))

    # set the disks ID correctly since call_instance_start needs the
    # correct drbd minor to create the symlinks
    for disk in instance.disks:
      self.cfg.SetDiskID(disk, src_node)

    activate_disks = (not instance.admin_up)

    if activate_disks:
      # Activate the instance disks if we'exporting a stopped instance
      feedback_fn("Activating disks for %s" % instance.name)
      _StartInstanceDisks(self, instance, None)

    try:
      helper = masterd.instance.ExportInstanceHelper(self, feedback_fn,
                                                     instance)

      helper.CreateSnapshots()
      try:
        if (self.op.shutdown and instance.admin_up and
            not self.remove_instance):
          assert not activate_disks
          feedback_fn("Starting instance %s" % instance.name)
          result = self.rpc.call_instance_start(src_node, instance, None, None)
          msg = result.fail_msg
          if msg:
            feedback_fn("Failed to start instance: %s" % msg)
            _ShutdownInstanceDisks(self, instance)
            raise errors.OpExecError("Could not start instance: %s" % msg)

        if self.export_mode == constants.EXPORT_MODE_LOCAL:
          (fin_resu, dresults) = helper.LocalExport(self.dst_node)
        elif self.export_mode == constants.EXPORT_MODE_REMOTE:
          connect_timeout = constants.RIE_CONNECT_TIMEOUT
          timeouts = masterd.instance.ImportExportTimeouts(connect_timeout)

          (key_name, _, _) = self.x509_key_name

          dest_ca_pem = \
            OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_PEM,
                                            self.dest_x509_ca)

          (fin_resu, dresults) = helper.RemoteExport(self.dest_disk_info,
                                                     key_name, dest_ca_pem,
                                                     timeouts)
      finally:
        helper.Cleanup()

      # Check for backwards compatibility
      assert len(dresults) == len(instance.disks)
      assert compat.all(isinstance(i, bool) for i in dresults), \
             "Not all results are boolean: %r" % dresults

    finally:
      if activate_disks:
        feedback_fn("Deactivating disks for %s" % instance.name)
        _ShutdownInstanceDisks(self, instance)

    # Remove instance if requested
    if self.remove_instance:
      if not (compat.all(dresults) and fin_resu):
        feedback_fn("Not removing instance %s as parts of the export failed" %
                    instance.name)
      else:
        feedback_fn("Removing instance %s" % instance.name)
        _RemoveInstance(self, feedback_fn, instance,
                        self.ignore_remove_failures)

    if self.export_mode == constants.EXPORT_MODE_LOCAL:
      self._CleanupExports(feedback_fn)

    return fin_resu, dresults


class LURemoveExport(NoHooksLU):
  """Remove exports related to the named instance.

  """
  _OP_REQP = ["instance_name"]
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {}
    # We need all nodes to be locked in order for RemoveExport to work, but we
    # don't need to lock the instance itself, as nothing will happen to it (and
    # we can remove exports also for a removed instance)
    self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET

  def CheckPrereq(self):
    """Check prerequisites.
    """
    pass

  def Exec(self, feedback_fn):
    """Remove any export.

    """
    instance_name = self.cfg.ExpandInstanceName(self.op.instance_name)
    # If the instance was not found we'll try with the name that was passed in.
    # This will only work if it was an FQDN, though.
    fqdn_warn = False
    if not instance_name:
      fqdn_warn = True
      instance_name = self.op.instance_name

    locked_nodes = self.acquired_locks[locking.LEVEL_NODE]
    exportlist = self.rpc.call_export_list(locked_nodes)
    found = False
    for node in exportlist:
      msg = exportlist[node].fail_msg
      if msg:
        self.LogWarning("Failed to query node %s (continuing): %s", node, msg)
        continue
      if instance_name in exportlist[node].payload:
        found = True
        result = self.rpc.call_export_remove(node, instance_name)
        msg = result.fail_msg
        if msg:
          logging.error("Could not remove export for instance %s"
                        " on node %s: %s", instance_name, node, msg)

    if fqdn_warn and not found:
      feedback_fn("Export not found. If trying to remove an export belonging"
                  " to a deleted instance please use its Fully Qualified"
                  " Domain Name.")


class TagsLU(NoHooksLU): # pylint: disable-msg=W0223
  """Generic tags LU.

  This is an abstract class which is the parent of all the other tags LUs.

  """

  def ExpandNames(self):
    self.needed_locks = {}
    if self.op.kind == constants.TAG_NODE:
      self.op.name = _ExpandNodeName(self.cfg, self.op.name)
      self.needed_locks[locking.LEVEL_NODE] = self.op.name
    elif self.op.kind == constants.TAG_INSTANCE:
      self.op.name = _ExpandInstanceName(self.cfg, self.op.name)
      self.needed_locks[locking.LEVEL_INSTANCE] = self.op.name

  def CheckPrereq(self):
    """Check prerequisites.

    """
    if self.op.kind == constants.TAG_CLUSTER:
      self.target = self.cfg.GetClusterInfo()
    elif self.op.kind == constants.TAG_NODE:
      self.target = self.cfg.GetNodeInfo(self.op.name)
    elif self.op.kind == constants.TAG_INSTANCE:
      self.target = self.cfg.GetInstanceInfo(self.op.name)
    else:
      raise errors.OpPrereqError("Wrong tag type requested (%s)" %
                                 str(self.op.kind), errors.ECODE_INVAL)


class LUGetTags(TagsLU):
  """Returns the tags of a given object.

  """
  _OP_REQP = ["kind", "name"]
  REQ_BGL = False

  def Exec(self, feedback_fn):
    """Returns the tag list.

    """
    return list(self.target.GetTags())


class LUSearchTags(NoHooksLU):
  """Searches the tags for a given pattern.

  """
  _OP_REQP = ["pattern"]
  REQ_BGL = False

  def ExpandNames(self):
    self.needed_locks = {}

  def CheckPrereq(self):
    """Check prerequisites.

    This checks the pattern passed for validity by compiling it.

    """
    try:
      self.re = re.compile(self.op.pattern)
    except re.error, err:
      raise errors.OpPrereqError("Invalid search pattern '%s': %s" %
                                 (self.op.pattern, err), errors.ECODE_INVAL)

  def Exec(self, feedback_fn):
    """Returns the tag list.

    """
    cfg = self.cfg
    tgts = [("/cluster", cfg.GetClusterInfo())]
    ilist = cfg.GetAllInstancesInfo().values()
    tgts.extend([("/instances/%s" % i.name, i) for i in ilist])
    nlist = cfg.GetAllNodesInfo().values()
    tgts.extend([("/nodes/%s" % n.name, n) for n in nlist])
    results = []
    for path, target in tgts:
      for tag in target.GetTags():
        if self.re.search(tag):
          results.append((path, tag))
    return results


class LUAddTags(TagsLU):
  """Sets a tag on a given object.

  """
  _OP_REQP = ["kind", "name", "tags"]
  REQ_BGL = False

  def CheckPrereq(self):
    """Check prerequisites.

    This checks the type and length of the tag name and value.

    """
    TagsLU.CheckPrereq(self)
    for tag in self.op.tags:
      objects.TaggableObject.ValidateTag(tag)

  def Exec(self, feedback_fn):
    """Sets the tag.

    """
    try:
      for tag in self.op.tags:
        self.target.AddTag(tag)
    except errors.TagError, err:
      raise errors.OpExecError("Error while setting tag: %s" % str(err))
    self.cfg.Update(self.target, feedback_fn)


class LUDelTags(TagsLU):
  """Delete a list of tags from a given object.

  """
  _OP_REQP = ["kind", "name", "tags"]
  REQ_BGL = False

  def CheckPrereq(self):
    """Check prerequisites.

    This checks that we have the given tag.

    """
    TagsLU.CheckPrereq(self)
    for tag in self.op.tags:
      objects.TaggableObject.ValidateTag(tag)
    del_tags = frozenset(self.op.tags)
    cur_tags = self.target.GetTags()
    if not del_tags <= cur_tags:
      diff_tags = del_tags - cur_tags
      diff_names = ["'%s'" % tag for tag in diff_tags]
      diff_names.sort()
      raise errors.OpPrereqError("Tag(s) %s not found" %
                                 (",".join(diff_names)), errors.ECODE_NOENT)

  def Exec(self, feedback_fn):
    """Remove the tag from the object.

    """
    for tag in self.op.tags:
      self.target.RemoveTag(tag)
    self.cfg.Update(self.target, feedback_fn)


class LUTestDelay(NoHooksLU):
  """Sleep for a specified amount of time.

  This LU sleeps on the master and/or nodes for a specified amount of
  time.

  """
  _OP_REQP = ["duration", "on_master", "on_nodes"]
  REQ_BGL = False

  def ExpandNames(self):
    """Expand names and set required locks.

    This expands the node list, if any.

    """
    self.needed_locks = {}
    if self.op.on_nodes:
      # _GetWantedNodes can be used here, but is not always appropriate to use
      # this way in ExpandNames. Check LogicalUnit.ExpandNames docstring for
      # more information.
      self.op.on_nodes = _GetWantedNodes(self, self.op.on_nodes)
      self.needed_locks[locking.LEVEL_NODE] = self.op.on_nodes

  def CheckPrereq(self):
    """Check prerequisites.

    """

  def Exec(self, feedback_fn):
    """Do the actual sleep.

    """
    if self.op.on_master:
      if not utils.TestDelay(self.op.duration):
        raise errors.OpExecError("Error during master delay test")
    if self.op.on_nodes:
      result = self.rpc.call_test_delay(self.op.on_nodes, self.op.duration)
      for node, node_result in result.items():
        node_result.Raise("Failure during rpc call to node %s" % node)


class IAllocator(object):
  """IAllocator framework.

  An IAllocator instance has three sets of attributes:
    - cfg that is needed to query the cluster
    - input data (all members of the _KEYS class attribute are required)
    - four buffer attributes (in|out_data|text), that represent the
      input (to the external script) in text and data structure format,
      and the output from it, again in two formats
    - the result variables from the script (success, info, nodes) for
      easy usage

  """
  # pylint: disable-msg=R0902
  # lots of instance attributes
  _ALLO_KEYS = [
    "name", "mem_size", "disks", "disk_template",
    "os", "tags", "nics", "vcpus", "hypervisor",
    ]
  _RELO_KEYS = [
    "name", "relocate_from",
    ]
  _EVAC_KEYS = [
    "evac_nodes",
    ]

  def __init__(self, cfg, rpc, mode, **kwargs):
    self.cfg = cfg
    self.rpc = rpc
    # init buffer variables
    self.in_text = self.out_text = self.in_data = self.out_data = None
    # init all input fields so that pylint is happy
    self.mode = mode
    self.mem_size = self.disks = self.disk_template = None
    self.os = self.tags = self.nics = self.vcpus = None
    self.hypervisor = None
    self.relocate_from = None
    self.name = None
    self.evac_nodes = None
    # computed fields
    self.required_nodes = None
    # init result fields
    self.success = self.info = self.result = None
    if self.mode == constants.IALLOCATOR_MODE_ALLOC:
      keyset = self._ALLO_KEYS
      fn = self._AddNewInstance
    elif self.mode == constants.IALLOCATOR_MODE_RELOC:
      keyset = self._RELO_KEYS
      fn = self._AddRelocateInstance
    elif self.mode == constants.IALLOCATOR_MODE_MEVAC:
      keyset = self._EVAC_KEYS
      fn = self._AddEvacuateNodes
    else:
      raise errors.ProgrammerError("Unknown mode '%s' passed to the"
                                   " IAllocator" % self.mode)
    for key in kwargs:
      if key not in keyset:
        raise errors.ProgrammerError("Invalid input parameter '%s' to"
                                     " IAllocator" % key)
      setattr(self, key, kwargs[key])

    for key in keyset:
      if key not in kwargs:
        raise errors.ProgrammerError("Missing input parameter '%s' to"
                                     " IAllocator" % key)
    self._BuildInputData(fn)

  def _ComputeClusterData(self):
    """Compute the generic allocator input data.

    This is the data that is independent of the actual operation.

    """
    cfg = self.cfg
    cluster_info = cfg.GetClusterInfo()
    # cluster data
    data = {
      "version": constants.IALLOCATOR_VERSION,
      "cluster_name": cfg.GetClusterName(),
      "cluster_tags": list(cluster_info.GetTags()),
      "enabled_hypervisors": list(cluster_info.enabled_hypervisors),
      # we don't have job IDs
      }
    iinfo = cfg.GetAllInstancesInfo().values()
    i_list = [(inst, cluster_info.FillBE(inst)) for inst in iinfo]

    # node data
    node_results = {}
    node_list = cfg.GetNodeList()

    if self.mode == constants.IALLOCATOR_MODE_ALLOC:
      hypervisor_name = self.hypervisor
    elif self.mode == constants.IALLOCATOR_MODE_RELOC:
      hypervisor_name = cfg.GetInstanceInfo(self.name).hypervisor
    elif self.mode == constants.IALLOCATOR_MODE_MEVAC:
      hypervisor_name = cluster_info.enabled_hypervisors[0]

    node_data = self.rpc.call_node_info(node_list, cfg.GetVGName(),
                                        hypervisor_name)
    node_iinfo = \
      self.rpc.call_all_instances_info(node_list,
                                       cluster_info.enabled_hypervisors)
    for nname, nresult in node_data.items():
      # first fill in static (config-based) values
      ninfo = cfg.GetNodeInfo(nname)
      pnr = {
        "tags": list(ninfo.GetTags()),
        "primary_ip": ninfo.primary_ip,
        "secondary_ip": ninfo.secondary_ip,
        "offline": ninfo.offline,
        "drained": ninfo.drained,
        "master_candidate": ninfo.master_candidate,
        }

      if not (ninfo.offline or ninfo.drained):
        nresult.Raise("Can't get data for node %s" % nname)
        node_iinfo[nname].Raise("Can't get node instance info from node %s" %
                                nname)
        remote_info = nresult.payload

        for attr in ['memory_total', 'memory_free', 'memory_dom0',
                     'vg_size', 'vg_free', 'cpu_total']:
          if attr not in remote_info:
            raise errors.OpExecError("Node '%s' didn't return attribute"
                                     " '%s'" % (nname, attr))
          if not isinstance(remote_info[attr], int):
            raise errors.OpExecError("Node '%s' returned invalid value"
                                     " for '%s': %s" %
                                     (nname, attr, remote_info[attr]))
        # compute memory used by primary instances
        i_p_mem = i_p_up_mem = 0
        for iinfo, beinfo in i_list:
          if iinfo.primary_node == nname:
            i_p_mem += beinfo[constants.BE_MEMORY]
            if iinfo.name not in node_iinfo[nname].payload:
              i_used_mem = 0
            else:
              i_used_mem = int(node_iinfo[nname].payload[iinfo.name]['memory'])
            i_mem_diff = beinfo[constants.BE_MEMORY] - i_used_mem
            remote_info['memory_free'] -= max(0, i_mem_diff)

            if iinfo.admin_up:
              i_p_up_mem += beinfo[constants.BE_MEMORY]

        # compute memory used by instances
        pnr_dyn = {
          "total_memory": remote_info['memory_total'],
          "reserved_memory": remote_info['memory_dom0'],
          "free_memory": remote_info['memory_free'],
          "total_disk": remote_info['vg_size'],
          "free_disk": remote_info['vg_free'],
          "total_cpus": remote_info['cpu_total'],
          "i_pri_memory": i_p_mem,
          "i_pri_up_memory": i_p_up_mem,
          }
        pnr.update(pnr_dyn)

      node_results[nname] = pnr
    data["nodes"] = node_results

    # instance data
    instance_data = {}
    for iinfo, beinfo in i_list:
      nic_data = []
      for nic in iinfo.nics:
        filled_params = cluster_info.SimpleFillNIC(nic.nicparams)
        nic_dict = {"mac": nic.mac,
                    "ip": nic.ip,
                    "mode": filled_params[constants.NIC_MODE],
                    "link": filled_params[constants.NIC_LINK],
                   }
        if filled_params[constants.NIC_MODE] == constants.NIC_MODE_BRIDGED:
          nic_dict["bridge"] = filled_params[constants.NIC_LINK]
        nic_data.append(nic_dict)
      pir = {
        "tags": list(iinfo.GetTags()),
        "admin_up": iinfo.admin_up,
        "vcpus": beinfo[constants.BE_VCPUS],
        "memory": beinfo[constants.BE_MEMORY],
        "os": iinfo.os,
        "nodes": [iinfo.primary_node] + list(iinfo.secondary_nodes),
        "nics": nic_data,
        "disks": [{"size": dsk.size, "mode": dsk.mode} for dsk in iinfo.disks],
        "disk_template": iinfo.disk_template,
        "hypervisor": iinfo.hypervisor,
        }
      pir["disk_space_total"] = _ComputeDiskSize(iinfo.disk_template,
                                                 pir["disks"])
      instance_data[iinfo.name] = pir

    data["instances"] = instance_data

    self.in_data = data

  def _AddNewInstance(self):
    """Add new instance data to allocator structure.

    This in combination with _AllocatorGetClusterData will create the
    correct structure needed as input for the allocator.

    The checks for the completeness of the opcode must have already been
    done.

    """
    disk_space = _ComputeDiskSize(self.disk_template, self.disks)

    if self.disk_template in constants.DTS_NET_MIRROR:
      self.required_nodes = 2
    else:
      self.required_nodes = 1
    request = {
      "name": self.name,
      "disk_template": self.disk_template,
      "tags": self.tags,
      "os": self.os,
      "vcpus": self.vcpus,
      "memory": self.mem_size,
      "disks": self.disks,
      "disk_space_total": disk_space,
      "nics": self.nics,
      "required_nodes": self.required_nodes,
      }
    return request

  def _AddRelocateInstance(self):
    """Add relocate instance data to allocator structure.

    This in combination with _IAllocatorGetClusterData will create the
    correct structure needed as input for the allocator.

    The checks for the completeness of the opcode must have already been
    done.

    """
    instance = self.cfg.GetInstanceInfo(self.name)
    if instance is None:
      raise errors.ProgrammerError("Unknown instance '%s' passed to"
                                   " IAllocator" % self.name)

    if instance.disk_template not in constants.DTS_NET_MIRROR:
      raise errors.OpPrereqError("Can't relocate non-mirrored instances",
                                 errors.ECODE_INVAL)

    if len(instance.secondary_nodes) != 1:
      raise errors.OpPrereqError("Instance has not exactly one secondary node",
                                 errors.ECODE_STATE)

    self.required_nodes = 1
    disk_sizes = [{'size': disk.size} for disk in instance.disks]
    disk_space = _ComputeDiskSize(instance.disk_template, disk_sizes)

    request = {
      "name": self.name,
      "disk_space_total": disk_space,
      "required_nodes": self.required_nodes,
      "relocate_from": self.relocate_from,
      }
    return request

  def _AddEvacuateNodes(self):
    """Add evacuate nodes data to allocator structure.

    """
    request = {
      "evac_nodes": self.evac_nodes
      }
    return request

  def _BuildInputData(self, fn):
    """Build input data structures.

    """
    self._ComputeClusterData()

    request = fn()
    request["type"] = self.mode
    self.in_data["request"] = request

    self.in_text = serializer.Dump(self.in_data)

  def Run(self, name, validate=True, call_fn=None):
    """Run an instance allocator and return the results.

    """
    if call_fn is None:
      call_fn = self.rpc.call_iallocator_runner

    result = call_fn(self.cfg.GetMasterNode(), name, self.in_text)
    result.Raise("Failure while running the iallocator script")

    self.out_text = result.payload
    if validate:
      self._ValidateResult()

  def _ValidateResult(self):
    """Process the allocator results.

    This will process and if successful save the result in
    self.out_data and the other parameters.

    """
    try:
      rdict = serializer.Load(self.out_text)
    except Exception, err:
      raise errors.OpExecError("Can't parse iallocator results: %s" % str(err))

    if not isinstance(rdict, dict):
      raise errors.OpExecError("Can't parse iallocator results: not a dict")

    # TODO: remove backwards compatiblity in later versions
    if "nodes" in rdict and "result" not in rdict:
      rdict["result"] = rdict["nodes"]
      del rdict["nodes"]

    for key in "success", "info", "result":
      if key not in rdict:
        raise errors.OpExecError("Can't parse iallocator results:"
                                 " missing key '%s'" % key)
      setattr(self, key, rdict[key])

    if not isinstance(rdict["result"], list):
      raise errors.OpExecError("Can't parse iallocator results: 'result' key"
                               " is not a list")
    self.out_data = rdict


class LUTestAllocator(NoHooksLU):
  """Run allocator tests.

  This LU runs the allocator tests

  """
  _OP_REQP = ["direction", "mode", "name"]

  def CheckPrereq(self):
    """Check prerequisites.

    This checks the opcode parameters depending on the director and mode test.

    """
    if self.op.mode == constants.IALLOCATOR_MODE_ALLOC:
      for attr in ["name", "mem_size", "disks", "disk_template",
                   "os", "tags", "nics", "vcpus"]:
        if not hasattr(self.op, attr):
          raise errors.OpPrereqError("Missing attribute '%s' on opcode input" %
                                     attr, errors.ECODE_INVAL)
      iname = self.cfg.ExpandInstanceName(self.op.name)
      if iname is not None:
        raise errors.OpPrereqError("Instance '%s' already in the cluster" %
                                   iname, errors.ECODE_EXISTS)
      if not isinstance(self.op.nics, list):
        raise errors.OpPrereqError("Invalid parameter 'nics'",
                                   errors.ECODE_INVAL)
      for row in self.op.nics:
        if (not isinstance(row, dict) or
            "mac" not in row or
            "ip" not in row or
            "bridge" not in row):
          raise errors.OpPrereqError("Invalid contents of the 'nics'"
                                     " parameter", errors.ECODE_INVAL)
      if not isinstance(self.op.disks, list):
        raise errors.OpPrereqError("Invalid parameter 'disks'",
                                   errors.ECODE_INVAL)
      for row in self.op.disks:
        if (not isinstance(row, dict) or
            "size" not in row or
            not isinstance(row["size"], int) or
            "mode" not in row or
            row["mode"] not in ['r', 'w']):
          raise errors.OpPrereqError("Invalid contents of the 'disks'"
                                     " parameter", errors.ECODE_INVAL)
      if not hasattr(self.op, "hypervisor") or self.op.hypervisor is None:
        self.op.hypervisor = self.cfg.GetHypervisorType()
    elif self.op.mode == constants.IALLOCATOR_MODE_RELOC:
      if not hasattr(self.op, "name"):
        raise errors.OpPrereqError("Missing attribute 'name' on opcode input",
                                   errors.ECODE_INVAL)
      fname = _ExpandInstanceName(self.cfg, self.op.name)
      self.op.name = fname
      self.relocate_from = self.cfg.GetInstanceInfo(fname).secondary_nodes
    elif self.op.mode == constants.IALLOCATOR_MODE_MEVAC:
      if not hasattr(self.op, "evac_nodes"):
        raise errors.OpPrereqError("Missing attribute 'evac_nodes' on"
                                   " opcode input", errors.ECODE_INVAL)
    else:
      raise errors.OpPrereqError("Invalid test allocator mode '%s'" %
                                 self.op.mode, errors.ECODE_INVAL)

    if self.op.direction == constants.IALLOCATOR_DIR_OUT:
      if not hasattr(self.op, "allocator") or self.op.allocator is None:
        raise errors.OpPrereqError("Missing allocator name",
                                   errors.ECODE_INVAL)
    elif self.op.direction != constants.IALLOCATOR_DIR_IN:
      raise errors.OpPrereqError("Wrong allocator test '%s'" %
                                 self.op.direction, errors.ECODE_INVAL)

  def Exec(self, feedback_fn):
    """Run the allocator test.

    """
    if self.op.mode == constants.IALLOCATOR_MODE_ALLOC:
      ial = IAllocator(self.cfg, self.rpc,
                       mode=self.op.mode,
                       name=self.op.name,
                       mem_size=self.op.mem_size,
                       disks=self.op.disks,
                       disk_template=self.op.disk_template,
                       os=self.op.os,
                       tags=self.op.tags,
                       nics=self.op.nics,
                       vcpus=self.op.vcpus,
                       hypervisor=self.op.hypervisor,
                       )
    elif self.op.mode == constants.IALLOCATOR_MODE_RELOC:
      ial = IAllocator(self.cfg, self.rpc,
                       mode=self.op.mode,
                       name=self.op.name,
                       relocate_from=list(self.relocate_from),
                       )
    elif self.op.mode == constants.IALLOCATOR_MODE_MEVAC:
      ial = IAllocator(self.cfg, self.rpc,
                       mode=self.op.mode,
                       evac_nodes=self.op.evac_nodes)
    else:
      raise errors.ProgrammerError("Uncatched mode %s in"
                                   " LUTestAllocator.Exec", self.op.mode)

    if self.op.direction == constants.IALLOCATOR_DIR_IN:
      result = ial.in_text
    else:
      ial.Run(self.op.allocator, validate=False)
      result = ial.out_text
    return result