Populate OS variants if an api >= 15 is present

[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=W0613,W0201

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

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


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
    self.LogInfo = processor.LogInfo
    self.LogStep = processor.LogStep
    # support for dry-run
    self.dry_run_result = None

    # 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)

    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

    """
    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"
    expanded_name = self.cfg.ExpandInstanceName(self.op.instance_name)
    if expanded_name is None:
      raise errors.OpPrereqError("Instance '%s' not known" %
                                  self.op.instance_name)
    self.needed_locks[locking.LEVEL_INSTANCE] = expanded_name
    self.op.instance_name = expanded_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):
  """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


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.OpProgrammerError: if the nodes parameter is wrong type

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

  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 = []
  for name in nodes:
    node = lu.cfg.ExpandNodeName(name)
    if node is None:
      raise errors.OpPrereqError("No such node name '%s'" % name)
    wanted.append(node)

  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'")

  if instances:
    wanted = []

    for name in instances:
      instance = lu.cfg.ExpandInstanceName(name)
      if instance is None:
        raise errors.OpPrereqError("No such instance name '%s'" % name)
      wanted.append(instance)

  else:
    wanted = utils.NiceSort(lu.cfg.GetInstanceList())
  return wanted


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))


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)))
  setattr(op, name, val)


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)


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)


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 = []
  c_nicparams = lu.cfg.GetClusterInfo().nicparams[constants.PP_DEFAULT]
  for nic in nics:
    ip = nic.ip
    mac = nic.mac
    filled_params = objects.FillDict(c_nicparams, 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)


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",
               ", ".join(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,
                               profile=constants.PP_DEFAULT):
  """Check that the brigdes needed by a list of nics exist.

  """
  c_nicparams = lu.cfg.GetClusterInfo().nicparams[profile]
  paramslist = [objects.FillDict(c_nicparams, 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)


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 _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)

  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))
    instancelist = self.cfg.GetInstanceList()
    if instancelist:
      raise errors.OpPrereqError("There are still %d instance(s) in"
                                 " this cluster." % len(instancelist))

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

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

    # 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:
      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")
    priv_key, pub_key, _ = ssh.GetUserFiles(constants.GANETI_RUNAS)
    utils.CreateBackup(priv_key)
    utils.CreateBackup(pub_key)
    return master


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")
  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")

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

  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, nodeinfo, file_list, local_cksum,
                  node_result, master_files, drbd_map, vg_name):
    """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 nodeinfo: L{objects.Node}
    @param nodeinfo: the node to check
    @param file_list: required list of files
    @param local_cksum: dictionary of local files and their checksums
    @param node_result: the results from the node
    @param master_files: list of files that only masters should have
    @param drbd_map: the useddrbd minors for this node, in
        form of minor: (instance, must_exist) which correspond to instances
        and their running status
    @param vg_name: Ganeti Volume Group (result of self.cfg.GetVGName())

    """
    node = nodeinfo.name
    _ErrorIf = self._ErrorIf

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

    # compares ganeti version
    local_version = constants.PROTOCOL_VERSION
    remote_version = node_result.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

    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

    # 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)

    # checks vg existence and size > 20G
    if vg_name is not None:
      vglist = node_result.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)

    # checks config file checksum

    remote_cksum = node_result.get(constants.NV_FILELIST, None)
    test = not isinstance(remote_cksum, dict)
    _ErrorIf(test, self.ENODEFILECHECK, node,
             "node hasn't returned file checksum data")
    if not test:
      for file_name in file_list:
        node_is_mc = nodeinfo.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)

    # checks ssh to any

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

    hyp_result = node_result.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)

    # check used drbd list
    if vg_name is not None:
      used_minors = node_result.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 not test:
        for minor, (iname, must_exist) in drbd_map.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 drbd_map
          _ErrorIf(test, self.ENODEDRBD, node,
                   "unallocated drbd minor %d is in use", minor)

  def _VerifyInstance(self, instance, instanceconfig, node_vol_is,
                      node_instance, n_offline):
    """Verify an instance.

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

    """
    _ErrorIf = self._ErrorIf
    node_current = instanceconfig.primary_node

    node_vol_should = {}
    instanceconfig.MapLVsByNode(node_vol_should)

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

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

    for node in node_instance:
      if (not node == node_current):
        test = instance in node_instance[node]
        _ErrorIf(test, self.EINSTANCEWRONGNODE, instance,
                 "instance should not run on node %s", node)

  def _VerifyOrphanVolumes(self, node_vol_should, node_vol_is):
    """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 in node_vol_is:
      for volume in node_vol_is[node]:
        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_instance):
    """Verify the list of running instances.

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

    """
    for node in node_instance:
      for o_inst in node_instance[node]:
        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_info, 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, nodeinfo in node_info.iteritems():
      # 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 nodeinfo['sinst-by-pnode'].iteritems():
        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 = nodeinfo['mfree'] < needed_mem
        self._ErrorIf(test, self.ENODEN1, node,
                      "not enough memory on to accommodate"
                      " failovers should peer node %s fail", prinode)

  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")

  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
    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)

    vg_name = self.cfg.GetVGName()
    hypervisors = self.cfg.GetClusterInfo().enabled_hypervisors
    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 = [] # List of offline nodes
    n_drained = [] # List of nodes being drained
    node_volume = {}
    node_instance = {}
    node_info = {}
    instance_cfg = {}

    # FIXME: verify OS list
    # do local checksums
    master_files = [constants.CLUSTER_CONF_FILE]

    file_names = ssconf.SimpleStore().GetFileList()
    file_names.append(constants.SSL_CERT_FILE)
    file_names.append(constants.RAPI_CERT_FILE)
    file_names.extend(master_files)

    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(),
      }
    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_DRBDLIST] = None
    all_nvinfo = self.rpc.call_node_verify(nodelist, node_verify_param,
                                           self.cfg.GetClusterName())

    cluster = self.cfg.GetClusterInfo()
    master_node = self.cfg.GetMasterNode()
    all_drbd_map = self.cfg.ComputeDRBDMap()

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

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

      if node == master_node:
        ntype = "master"
      elif node_i.master_candidate:
        ntype = "master candidate"
      elif node_i.drained:
        ntype = "drained"
        n_drained.append(node)
      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:
        continue

      nresult = all_nvinfo[node].payload
      node_drbd = {}
      for minor, instance in all_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)
      self._VerifyNode(node_i, file_names, local_checksums,
                       nresult, master_files, node_drbd, vg_name)

      lvdata = nresult.get(constants.NV_LVLIST, "Missing LV data")
      if vg_name is None:
        node_volume[node] = {}
      elif isinstance(lvdata, basestring):
        _ErrorIf(True, self.ENODELVM, node, "LVM problem on node: %s",
                 utils.SafeEncode(lvdata))
        node_volume[node] = {}
      elif not isinstance(lvdata, dict):
        _ErrorIf(True, self.ENODELVM, node, "rpc call to node failed (lvlist)")
        continue
      else:
        node_volume[node] = lvdata

      # node_instance
      idata = nresult.get(constants.NV_INSTANCELIST, None)
      test = not isinstance(idata, list)
      _ErrorIf(test, self.ENODEHV, node,
               "rpc call to node failed (instancelist)")
      if test:
        continue

      node_instance[node] = idata

      # node_info
      nodeinfo = nresult.get(constants.NV_HVINFO, None)
      test = not isinstance(nodeinfo, dict)
      _ErrorIf(test, self.ENODEHV, node, "rpc call to node failed (hvinfo)")
      if test:
        continue

      try:
        node_info[node] = {
          "mfree": int(nodeinfo['memory_free']),
          "pinst": [],
          "sinst": [],
          # dictionary holding all instances this node is secondary for,
          # grouped by their primary node. Each key is a cluster node, and each
          # value is a list of instances which have the key as primary and the
          # current node as secondary.  this is handy to calculate N+1 memory
          # availability if you can only failover from a primary to its
          # secondary.
          "sinst-by-pnode": {},
        }
        # 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 test:
            continue
          node_info[node]["dfree"] = int(nresult[constants.NV_VGLIST][vg_name])
      except (ValueError, KeyError):
        _ErrorIf(True, self.ENODERPC, node,
                 "node returned invalid nodeinfo, check lvm/hypervisor")
        continue

    node_vol_should = {}

    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_volume,
                           node_instance, n_offline)
      inst_nodes_offline = []

      inst_config.MapLVsByNode(node_vol_should)

      instance_cfg[instance] = inst_config

      pnode = inst_config.primary_node
      _ErrorIf(pnode not in node_info and pnode not in n_offline,
               self.ENODERPC, pnode, "instance %s, connection to"
               " primary node failed", instance)
      if pnode in node_info:
        node_info[pnode]['pinst'].append(instance)

      if pnode in n_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 len(inst_config.secondary_nodes) == 0:
        i_non_redundant.append(instance)
      _ErrorIf(len(inst_config.secondary_nodes) > 1,
               self.EINSTANCELAYOUT, instance,
               "instance has multiple secondary nodes", code="WARNING")

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

      for snode in inst_config.secondary_nodes:
        _ErrorIf(snode not in node_info and snode not in n_offline,
                 self.ENODERPC, snode,
                 "instance %s, connection to secondary node"
                 "failed", instance)

        if snode in node_info:
          node_info[snode]['sinst'].append(instance)
          if pnode not in node_info[snode]['sinst-by-pnode']:
            node_info[snode]['sinst-by-pnode'][pnode] = []
          node_info[snode]['sinst-by-pnode'][pnode].append(instance)

        if snode in n_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",
               ", ".join(inst_nodes_offline))

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

    feedback_fn("* Verifying remaining instances")
    self._VerifyOrphanInstances(instancelist, node_instance)

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

    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." % len(n_offline))

    if n_drained:
      feedback_fn("  - NOTICE: %d drained node(s) found." % len(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:
        show_node_header = True
        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 test:
          # 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 = 1

      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_inactive, 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'")

    if self.op.instances:
      self.wanted_names = []
      for name in self.op.instances:
        full_name = self.cfg.ExpandInstanceName(name)
        if full_name is None:
          raise errors.OpPrereqError("Instance '%s' not known" % 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)
          changed.append((instance.name, idx, size))
        if self._EnsureChildSizes(disk):
          self.cfg.Update(instance)
          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()
    return env, [mn], [mn]

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

    """
    hostname = utils.HostInfo(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")
    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)

    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)

      # 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

    """
    if not hasattr(self.op, "candidate_pool_size"):
      self.op.candidate_pool_size = 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))
      if self.op.candidate_pool_size < 1:
        raise errors.OpPrereqError("At least one master candidate needed")

  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")

    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))

    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 = objects.FillDict(
        cluster.beparams[constants.PP_DEFAULT], self.op.beparams)

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

    # hypervisor list/parameters
    self.new_hvparams = objects.FillDict(cluster.hvparams, {})
    if self.op.hvparams:
      if not isinstance(self.op.hvparams, dict):
        raise errors.OpPrereqError("Invalid 'hvparams' parameter on input")
      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)

    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")
      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))
    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)

  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.enabled_hypervisors is not None:
      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, [])

    self.cfg.Update(self.cluster)


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.GetNodeList()
  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.HMAC_CLUSTER_KEY,
                   ])

  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())
    _RedistributeAncillaryFiles(self)


def _WaitForSync(lu, instance, oneshot=False, unlock=False):
  """Sleep and poll for an instance's disk to sync.

  """
  if not instance.disks:
    return True

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

  node = instance.primary_node

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

  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, instance.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, instance.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 = "%d estimated seconds remaining" % mstat.estimated_time
          max_time = mstat.estimated_time
        else:
          rem_time = "no time estimate"
        lu.proc.LogInfo("- device %s: %5.2f%% done, %s" %
                        (instance.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")

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

    _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(node_list, rlist):
    """Remaps a per-node return list into an a per-os per-node dictionary

    @param node_list: a list with the names of all nodes
    @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 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))
    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(valid_nodes, node_data)
    output = []
    for os_name, os_data in pol.items():
      row = []
      for field in self.op.output_fields:
        if field == "name":
          val = os_name
        elif field == "valid":
          val = utils.all([osl and osl[0][1] for osl in os_data.values()])
        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
        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()
    if self.op.node_name in all_nodes:
      all_nodes.remove(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.

    """
    node = self.cfg.GetNodeInfo(self.cfg.ExpandNodeName(self.op.node_name))
    if node is None:
      raise errors.OpPrereqError, ("Node '%s' is unknown." % self.op.node_name)

    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.")

    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)
    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)

    # 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:
      h_results = hm.RunPhase(constants.HOOKS_PHASE_POST, [node.name])
    except:
      self.LogWarning("Errors occurred running hooks on %s" % node.name)

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


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

  """
  _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):
      instancelist = self.cfg.GetInstanceList()

      for instance_name in instancelist:
        inst = self.cfg.GetInstanceInfo(instance_name)
        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("node")

  def ExpandNames(self):
    storage_type = self.op.storage_type

    if storage_type not in constants.VALID_STORAGE_FIELDS:
      raise errors.OpPrereqError("Unknown storage type: %s" % storage_type)

    dynamic_fields = constants.VALID_STORAGE_FIELDS[storage_type]

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

    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 as it's only known to the LU
    while "node" in fields:
      fields.remove("node")

    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 == "node":
            val = node
          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):
    node_name = self.cfg.ExpandNodeName(self.op.node_name)
    if node_name is None:
      raise errors.OpPrereqError("Invalid node name '%s'" % self.op.node_name)

    self.op.node_name = node_name

    storage_type = self.op.storage_type
    if storage_type not in constants.VALID_STORAGE_FIELDS:
      raise errors.OpPrereqError("Unknown storage type: %s" % 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)

    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)))

  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 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.HostInfo(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")
    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)
    elif self.op.readd and node not in node_list:
      raise errors.OpPrereqError("Node %s is not in the configuration" % node)

    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.primary_ip != primary_ip or
            existing_node.secondary_ip != secondary_ip):
          raise errors.OpPrereqError("Readded node doesn't have the same IP"
                                     " address configuration as before")
        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)

    # 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")
      else:
        raise errors.OpPrereqError("The master has a private ip but the"
                                   " new node doesn't have one")

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

    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")

    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
      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

    # 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
    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:
      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)
      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)
      # 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)


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):
    node_name = self.cfg.ExpandNodeName(self.op.node_name)
    if node_name is None:
      raise errors.OpPrereqError("Invalid node name '%s'" % self.op.node_name)
    self.op.node_name = node_name
    _CheckBooleanOpField(self.op, 'master_candidate')
    _CheckBooleanOpField(self.op, 'offline')
    _CheckBooleanOpField(self.op, 'drained')
    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")
    if all_mods.count(True) > 1:
      raise errors.OpPrereqError("Can't set the node into more than one"
                                 " state at the same time")

  def ExpandNames(self):
    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")

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

    if (node.master_candidate and
        (self.op.master_candidate == False or offline_or_drain)):
      cp_size = self.cfg.GetClusterInfo().candidate_pool_size
      mc_now, mc_should, mc_max = self.cfg.GetMasterCandidateStats()
      if mc_now <= cp_size:
        msg = ("Not enough master candidates (desired"
               " %d, new value will be %d)" % (cp_size, mc_now-1))
        # Only allow forcing the operation if it's an offline/drain operation,
        # and we could not possibly promote more nodes.
        # FIXME: this can still lead to issues if in any way another node which
        # could be promoted appears in the meantime.
        if self.op.force and offline_or_drain and mc_should == mc_max:
          self.LogWarning(msg)
        else:
          raise errors.OpPrereqError(msg)

    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)

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

    # this will trigger configuration file update, if needed
    self.cfg.Update(node)
    # 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):
    node_name = self.cfg.ExpandNodeName(self.op.node_name)
    if node_name is None:
      raise errors.OpPrereqError("Invalid node name '%s'" % self.op.node_name)
    self.op.node_name = node_name
    if 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")

  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()
    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]),
      "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,
      "ctime": cluster.ctime,
      "mtime": cluster.mtime,
      "uuid": cluster.uuid,
      "tags": list(cluster.GetTags()),
      }

    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":
        return 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, 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 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
  # 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 instance.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 instance.disks:
    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
    device_info.append((instance.primary_node, inst_disk.iv_name,
                        result.payload))

  # 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 instance.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):
  """Shutdown block devices of an instance.

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

  """
  pnode = instance.primary_node
  ins_l = lu.rpc.call_instance_list([pnode], [instance.hypervisor])[pnode]
  ins_l.Raise("Can't contact node %s" % pnode)

  if instance.name in ins_l.payload:
    raise errors.OpExecError("Instance is running, can't shutdown"
                             " block devices.")

  _ShutdownInstanceDisks(lu, instance)


def _ShutdownInstanceDisks(lu, instance, 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
  for disk in instance.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)
  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))
  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))


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), ))
      # 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), ))

      # check hypervisor parameter syntax (locally)
      cluster = self.cfg.GetClusterInfo()
      utils.ForceDictType(self.hvparams, constants.HVS_PARAMETER_TYPES)
      filled_hvp = objects.FillDict(cluster.hvparams[instance.hypervisor],
                                    instance.hvparams)
      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)
    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 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,
      }
    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)
      result.Raise("Could not reboot instance")
    else:
      result = self.rpc.call_instance_shutdown(node_current, instance)
      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 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.

    """
    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
    self.cfg.MarkInstanceDown(instance.name)
    result = self.rpc.call_instance_shutdown(node_current, instance)
    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)
    if instance.admin_up:
      raise errors.OpPrereqError("Instance '%s' is marked to be up" %
                                 self.op.instance_name)
    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)
    if remote_info.payload:
      raise errors.OpPrereqError("Instance '%s' is running on the node %s" %
                                 (self.op.instance_name,
                                  instance.primary_node))

    self.op.os_type = getattr(self.op, "os_type", None)
    if self.op.os_type is not None:
      # OS verification
      pnode = self.cfg.GetNodeInfo(
        self.cfg.ExpandNodeName(instance.primary_node))
      if pnode is None:
        raise errors.OpPrereqError("Primary node '%s' is unknown" %
                                   self.op.pnode)
      result = self.rpc.call_os_get(pnode.name, self.op.os_type)
      result.Raise("OS '%s' not in supported OS list for primary node %s" %
                   (self.op.os_type, pnode.name), prereq=True)

    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)

    _StartInstanceDisks(self, inst, None)
    try:
      feedback_fn("Running the instance OS create scripts...")
      result = self.rpc.call_instance_os_add(inst.primary_node, inst, True)
      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")
    for item in self.op.disks:
      if (not isinstance(item, int) or
          item < 0):
        raise errors.OpPrereqError("Invalid disk specification '%s'" %
                                   str(item))

  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)
    if instance.admin_up:
      raise errors.OpPrereqError("Instance '%s' is marked to be up" %
                                 self.op.instance_name)
    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)
    if remote_info.payload:
      raise errors.OpPrereqError("Instance '%s' is running on the node %s" %
                                 (self.op.instance_name,
                                  instance.primary_node))

    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)

    self.instance = instance

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

    """
    to_skip = []
    for idx, disk 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.

    """
    instance = self.cfg.GetInstanceInfo(
      self.cfg.ExpandInstanceName(self.op.instance_name))
    if instance is None:
      raise errors.OpPrereqError("Instance '%s' not known" %
                                 self.op.instance_name)
    _CheckNodeOnline(self, instance.primary_node)

    if instance.admin_up:
      raise errors.OpPrereqError("Instance '%s' is marked to be up" %
                                 self.op.instance_name)
    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)
    if remote_info.payload:
      raise errors.OpPrereqError("Instance '%s' is running on the node %s" %
                                 (self.op.instance_name,
                                  instance.primary_node))
    self.instance = instance

    # new name verification
    name_info = utils.HostInfo(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)

    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))


  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)
      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 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)
    nl = [self.cfg.GetMasterNode()]
    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

  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)
    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))

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

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

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

    self.cfg.RemoveInstance(instance.name)
    self.remove_locks[locking.LEVEL_INSTANCE] = instance.name


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

  """
  _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] +
                                  ["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.

    """
    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)
      i_be = cluster.FillBE(instance)
      i_nicp = [objects.FillDict(cluster.nicparams[constants.PP_DEFAULT],
                                 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):
          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 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 = {
      "IGNORE_CONSISTENCY": self.op.ignore_consistency,
      }
    env.update(_BuildInstanceHookEnvByObject(self, self.instance))
    nl = [self.cfg.GetMasterNode()] + list(self.instance.secondary_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

    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.")

    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]

    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 instance.admin_up and not self.op.ignore_consistency:
          raise errors.OpExecError("Disk %s is degraded on target node,"
                                   " aborting failover." % dev.iv_name)

    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)
    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)

    # 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
    env = _BuildInstanceHookEnvByObject(self, instance)
    env["MIGRATE_LIVE"] = self.op.live
    env["MIGRATE_CLEANUP"] = self.op.cleanup
    nl = [self.cfg.GetMasterNode()] + list(instance.secondary_nodes)
    return env, nl, nl


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 ExpandNames(self):
    self._ExpandAndLockInstance()
    target_node = self.cfg.ExpandNodeName(self.op.target_node)
    if target_node is None:
      raise errors.OpPrereqError("Node '%s' not known" %
                                  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,
      }
    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))

    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")

    _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)
    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)

    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 = self.cfg.ExpandNodeName(self.op.node_name)
    if self.op.node_name is None:
      raise errors.OpPrereqError("Node '%s' not known" % 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 = self.cfg.GetInstanceInfo(
      self.cfg.ExpandInstanceName(self.instance_name))
    if instance is None:
      raise errors.OpPrereqError("Instance '%s' not known" %
                                 self.instance_name)

    if instance.disk_template != constants.DT_DRBD8:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " drbd8, cannot migrate.")

    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, target_node, "migrating instance %s" %
                         instance.name, i_be[constants.BE_MEMORY],
                         instance.hypervisor)

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

    if not self.cleanup:
      _CheckNodeNotDrained(self, target_node)
      result = self.rpc.call_instance_migratable(instance.primary_node,
                                                 instance)
      result.Raise("Can't migrate, please use failover", prereq=True)

    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)
      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, 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._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._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)

    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()
    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()
  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")

    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", "disk_template",
              "mode", "start",
              "wait_for_sync", "ip_check", "nics",
              "hvparams", "beparams"]
  REQ_BGL = False

  def _ExpandNode(self, node):
    """Expands and checks one node name.

    """
    node_full = self.cfg.ExpandNodeName(node)
    if node_full is None:
      raise errors.OpPrereqError("Unknown node %s" % node)
    return node_full

  def ExpandNames(self):
    """ExpandNames for CreateInstance.

    Figure out the right locks for instance creation.

    """
    self.needed_locks = {}

    # set optional parameters to none if they don't exist
    for attr in ["pnode", "snode", "iallocator", "hypervisor"]:
      if not hasattr(self.op, attr):
        setattr(self.op, attr, None)

    # cheap checks, mostly valid constants given

    # verify creation mode
    if self.op.mode not in (constants.INSTANCE_CREATE,
                            constants.INSTANCE_IMPORT):
      raise errors.OpPrereqError("Invalid instance creation mode '%s'" %
                                 self.op.mode)

    # disk template and mirror node verification
    if self.op.disk_template not in constants.DISK_TEMPLATES:
      raise errors.OpPrereqError("Invalid disk template name")

    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)))

    # check hypervisor parameter syntax (locally)
    utils.ForceDictType(self.op.hvparams, constants.HVS_PARAMETER_TYPES)
    filled_hvp = objects.FillDict(cluster.hvparams[self.op.hypervisor],
                                  self.op.hvparams)
    hv_type = hypervisor.GetHypervisor(self.op.hypervisor)
    hv_type.CheckParameterSyntax(filled_hvp)
    self.hv_full = filled_hvp

    # fill and remember the beparams dict
    utils.ForceDictType(self.op.beparams, constants.BES_PARAMETER_TYPES)
    self.be_full = objects.FillDict(cluster.beparams[constants.PP_DEFAULT],
                                    self.op.beparams)

    #### instance parameters check

    # instance name verification
    hostname1 = utils.HostInfo(self.op.instance_name)
    self.op.instance_name = instance_name = hostname1.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)

    self.add_locks[locking.LEVEL_INSTANCE] = instance_name

    # 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:
        nic_ip = hostname1.ip
      else:
        if not utils.IsValidIP(ip):
          raise errors.OpPrereqError("Given IP address '%s' doesn't look"
                                     " like a valid IP" % ip)
        nic_ip = ip

      # TODO: check the ip for uniqueness !!
      if nic_mode == constants.NIC_MODE_ROUTED and not nic_ip:
        raise errors.OpPrereqError("Routed nic mode requires an ip address")

      # MAC address verification
      mac = nic.get("mac", constants.VALUE_AUTO)
      if mac not in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
        if not utils.IsValidMac(mac.lower()):
          raise errors.OpPrereqError("Invalid MAC address specified: %s" %
                                     mac)
        else:
          # or validate/reserve the current one
          if self.cfg.IsMacInUse(mac):
            raise errors.OpPrereqError("MAC address %s already in use"
                                       " in cluster" % mac)

      # 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")
      elif bridge and nic_mode == constants.NIC_MODE_ROUTED:
        raise errors.OpPrereqError("Cannot pass 'bridge' on a routed nic")
      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 = objects.FillDict(cluster.nicparams[constants.PP_DEFAULT],
                                      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)
      size = disk.get("size", None)
      if size is None:
        raise errors.OpPrereqError("Missing disk size")
      try:
        size = int(size)
      except ValueError:
        raise errors.OpPrereqError("Invalid disk size '%s'" % size)
      self.disks.append({"size": size, "mode": mode})

    # used in CheckPrereq for ip ping check
    self.check_ip = hostname1.ip

    # 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)

    if self.op.file_storage_dir and os.path.isabs(self.op.file_storage_dir):
      raise errors.OpPrereqError("File storage directory path not absolute")

    ### 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")

    if self.op.iallocator:
      self.needed_locks[locking.LEVEL_NODE] = locking.ALL_SET
    else:
      self.op.pnode = self._ExpandNode(self.op.pnode)
      nodelist = [self.op.pnode]
      if self.op.snode is not None:
        self.op.snode = self._ExpandNode(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.")
      else:
        self.op.src_node = src_node = self._ExpandNode(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 = \
            os.path.join(constants.EXPORT_DIR, src_path)

    else: # INSTANCE_CREATE
      if getattr(self.op, "os_type", None) is None:
        raise errors.OpPrereqError("No guest OS specified")

  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))
    if len(ial.nodes) != ial.required_nodes:
      raise errors.OpPrereqError("iallocator '%s' returned invalid number"
                                 " of nodes (%s), required %s" %
                                 (self.op.iallocator, len(ial.nodes),
                                  ial.required_nodes))
    self.op.pnode = ial.nodes[0]
    self.LogInfo("Selected nodes for instance %s via iallocator %s: %s",
                 self.op.instance_name, self.op.iallocator,
                 ", ".join(ial.nodes))
    if ial.required_nodes == 2:
      self.op.snode = ial.nodes[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 CheckPrereq(self):
    """Check prerequisites.

    """
    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")

    if 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 = os.path.join(constants.EXPORT_DIR,
                                                       src_path)
            break
        if not found:
          raise errors.OpPrereqError("No export found for relative path %s" %
                                      src_path)

      _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")

      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))

      # 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))

      self.op.os_type = export_info.get(constants.INISECT_EXP, 'os')
      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 = os.path.join(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')
      # FIXME: int() here could throw a ValueError on broken exports
      exp_nic_count = int(export_info.get(constants.INISECT_INS, 'nic_count'))
      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.start and not self.op.ip_check:
      raise errors.OpPrereqError("Cannot ignore IP address conflicts when"
                                 " adding an instance in start mode")

    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))

    #### 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()

    #### 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)
    if pnode.drained:
      raise errors.OpPrereqError("Cannot use drained primary node '%s'" %
                                 pnode.name)

    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")
      if self.op.snode == pnode.name:
        raise errors.OpPrereqError("The secondary node cannot be"
                                   " the primary node.")
      _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 req_size is not None:
      nodeinfo = self.rpc.call_node_info(nodenames, self.cfg.GetVGName(),
                                         self.op.hypervisor)
      for node in nodenames:
        info = nodeinfo[node]
        info.Raise("Cannot get current information from node %s" % node)
        info = info.payload
        vg_free = info.get('vg_free', None)
        if not isinstance(vg_free, int):
          raise errors.OpPrereqError("Can't compute free disk space on"
                                     " node %s" % node)
        if req_size > vg_free:
          raise errors.OpPrereqError("Not enough disk space on target node %s."
                                     " %d MB available, %d MB required" %
                                     (node, vg_free, req_size))

    _CheckHVParams(self, nodenames, self.op.hypervisor, self.op.hvparams)

    # os verification
    result = self.rpc.call_os_get(pnode.name, self.op.os_type)
    result.Raise("OS '%s' not in supported os list for primary node %s" %
                 (self.op.os_type, pnode.name), prereq=True)

    _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 self.op.vnc_bind_address is None:
    ##  self.op.vnc_bind_address = constants.VNC_DEFAULT_BIND_ADDRESS

    # 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 = os.path.normpath(os.path.join(
                                        self.cfg.GetFileStorageDir(),
                                        string_file_storage_dir, instance))


    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,
                            )

    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)
    # 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")

    feedback_fn("creating os for instance %s on node %s" %
                (instance, pnode_name))

    if iobj.disk_template != constants.DT_DISKLESS:
      if self.op.mode == constants.INSTANCE_CREATE:
        feedback_fn("* running the instance OS create scripts...")
        result = self.rpc.call_instance_os_add(pnode_name, iobj, False)
        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...")
        src_node = self.op.src_node
        src_images = self.src_images
        cluster_name = self.cfg.GetClusterName()
        import_result = self.rpc.call_instance_os_import(pnode_name, iobj,
                                                         src_node, src_images,
                                                         cluster_name)
        msg = import_result.fail_msg
        if msg:
          self.LogWarning("Error while importing the disk images for instance"
                          " %s on node %s: %s" % (instance, pnode_name, 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)
      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

    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 = self.cfg.ExpandNodeName(self.op.remote_node)
      if remote_node is None:
        raise errors.OpPrereqError("Node '%s' not known" %
                                   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)

    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

    TLReplaceDisks.CheckArguments(constants.REPLACE_DISK_CHG,
                                  self.op.remote_node,
                                  self.op.iallocator)

  def ExpandNames(self):
    self.op.node_name = self.cfg.ExpandNodeName(self.op.node_name)
    if self.op.node_name is None:
      raise errors.OpPrereqError("Node '%s' not known" % 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:
      remote_node = self.cfg.ExpandNodeName(self.op.remote_node)
      if remote_node is None:
        raise errors.OpPrereqError("Node '%s' not known" %
                                   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:
      raise errors.OpPrereqError("Invalid parameters")

    # 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, [])
      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):
    """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

    # 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")

      if remote_node is not None and iallocator is not None:
        raise errors.OpPrereqError("Give either the iallocator or the new"
                                   " secondary, not both")

    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")

  @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))

    if len(ial.nodes) != ial.required_nodes:
      raise errors.OpPrereqError("iallocator '%s' returned invalid number"
                                 " of nodes (%s), required %s" %
                                 (len(ial.nodes), ial.required_nodes))

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

    if self.instance.disk_template != constants.DT_DRBD8:
      raise errors.OpPrereqError("Can only run replace disks for DRBD8-based"
                                 " instances")

    if len(self.instance.secondary_nodes) != 1:
      raise errors.OpPrereqError("The instance has a strange layout,"
                                 " expected one secondary but found %d" %
                                 len(self.instance.secondary_nodes))

    secondary_node = self.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,
                                       self.instance.name, secondary_node)

    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.")

    if remote_node == secondary_node:
      raise errors.OpPrereqError("The specified node is already the"
                                 " secondary node of the instance.")

    if self.disks and self.mode in (constants.REPLACE_DISK_AUTO,
                                    constants.REPLACE_DISK_CHG):
      raise errors.OpPrereqError("Cannot specify disks to be replaced")

    if self.mode == constants.REPLACE_DISK_AUTO:
      faulty_primary = self._FindFaultyDisks(self.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)

      if faulty_primary:
        self.disks = faulty_primary
        self.target_node = self.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 = self.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 = self.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 = self.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 = self.instance.primary_node
        self.target_node = secondary_node
        check_nodes = [self.new_node, self.other_node]

        _CheckNodeNotDrained(self.lu, remote_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:
      self.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 not self.disks:
      feedback_fn("No disks need replacement")
      return

    feedback_fn("Replacing disk(s) %s for %s" %
                (", ".join([str(i) for i in 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:
        return self._ExecDrbd8Secondary()
      else:
        return self._ExecDrbd8DiskOnly()

    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, old_lvs, new_lvs) 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, (dev, 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 _ExecDrbd8DiskOnly(self):
    """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)

    # 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(5, steps_total, "Sync devices")
    _WaitForSync(self.lu, self.instance, unlock=True)

    # Check all devices manually
    self._CheckDevices(self.instance.primary_node, iv_names)

    # Step: remove old storage
    self.lu.LogStep(6, steps_total, "Removing old storage")
    self._RemoveOldStorage(self.target_node, iv_names)

  def _ExecDrbd8Secondary(self):
    """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:
        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)

    # 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"))

    # 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(5, steps_total, "Sync devices")
    _WaitForSync(self.lu, self.instance, unlock=True)

    # Check all devices manually
    self._CheckDevices(self.instance.primary_node, iv_names)

    # Step: remove old storage
    self.lu.LogStep(6, 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):
    node_name = self.cfg.ExpandNodeName(self.op.node_name)
    if node_name is None:
      raise errors.OpPrereqError("Invalid node name '%s'" % self.op.node_name)

    self.op.node_name = node_name

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

  def _CheckFaultyDisks(self, instance, node_name):
    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))

  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)

    # Check whether any instance on this node has faulty disks
    for inst in _GetNodeInstances(self.cfg, self.op.node_name):
      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 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(),
      self.instance.primary_node,
      ]
    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.DT_PLAIN, constants.DT_DRBD8):
      raise errors.OpPrereqError("Instance's disk layout does not support"
                                 " growing.")

    self.disk = instance.FindDisk(self.op.disk)

    nodeinfo = self.rpc.call_node_info(nodenames, self.cfg.GetVGName(),
                                       instance.hypervisor)
    for node in nodenames:
      info = nodeinfo[node]
      info.Raise("Cannot get current information from node %s" % node)
      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" % node)
      if self.op.amount > vg_free:
        raise errors.OpPrereqError("Not enough disk space on target node %s:"
                                   " %d MiB available, %d MiB required" %
                                   (node, vg_free, self.op.amount))

  def Exec(self, feedback_fn):
    """Execute disk grow.

    """
    instance = self.instance
    disk = self.disk
    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)
    disk.RecordGrow(self.op.amount)
    self.cfg.Update(instance)
    if self.op.wait_for_sync:
      disk_abort = not _WaitForSync(self, instance)
      if disk_abort:
        self.proc.LogWarning("Warning: disk sync-ing has not returned a good"
                             " status.\nPlease check the instance.")


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'")

    if self.op.instances:
      self.wanted_names = []
      for name in self.op.instances:
        full_name = self.cfg.ExpandInstanceName(name)
        if full_name is None:
          raise errors.OpPrereqError("Instance '%s' not known" % 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),
        "disks": disks,
        "hypervisor": instance.hypervisor,
        "network_port": instance.network_port,
        "hv_instance": instance.hvparams,
        "hv_actual": cluster.FillHV(instance),
        "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 = {}
    self.op.force = getattr(self.op, "force", False)
    if not (self.op.nics or self.op.disks or
            self.op.hvparams or self.op.beparams):
      raise errors.OpPrereqError("No changes submitted")

    # Disk validation
    disk_addremove = 0
    for disk_op, disk_dict in self.op.disks:
      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")
        if not isinstance(disk_dict, dict):
          msg = "Invalid disk value: expected dict, got '%s'" % disk_dict
          raise errors.OpPrereqError(msg)

      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)
        size = disk_dict.get('size', None)
        if size is None:
          raise errors.OpPrereqError("Required disk parameter size missing")
        try:
          size = int(size)
        except ValueError, err:
          raise errors.OpPrereqError("Invalid disk size parameter: %s" %
                                     str(err))
        disk_dict['size'] = size
      else:
        # modification of disk
        if 'size' in disk_dict:
          raise errors.OpPrereqError("Disk size change not possible, use"
                                     " grow-disk")

    if disk_addremove > 1:
      raise errors.OpPrereqError("Only one disk add or remove operation"
                                 " supported at a time")

    # NIC validation
    nic_addremove = 0
    for nic_op, nic_dict in self.op.nics:
      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")
        if not isinstance(nic_dict, dict):
          msg = "Invalid nic value: expected dict, got '%s'" % nic_dict
          raise errors.OpPrereqError(msg)

      # 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)

      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")
      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):
          if not utils.IsValidMac(nic_mac):
            raise errors.OpPrereqError("Invalid MAC address %s" % 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")

    if nic_addremove > 1:
      raise errors.OpPrereqError("Only one NIC add or remove operation"
                                 " supported at a time")

  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, 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)
      c_nicparams = self.cluster.nicparams[constants.PP_DEFAULT]
      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 = objects.FillDict(c_nicparams, 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)
    nl = [self.cfg.GetMasterNode()] + list(self.instance.all_nodes)
    return env, nl, nl

  def _GetUpdatedParams(self, old_params, update_dict,
                        default_values, parameter_types):
    """Return the new params dict for the given params.

    @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
    @type default_values: dict
    @param default_values: default values for the filled parameters
    @type parameter_types: dict
    @param parameter_types: dict mapping target dict keys to types
                            in constants.ENFORCEABLE_TYPES
    @rtype: (dict, dict)
    @return: (new_parameters, filled_parameters)

    """
    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
    utils.ForceDictType(params_copy, parameter_types)
    params_filled = objects.FillDict(default_values, params_copy)
    return (params_copy, params_filled)

  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)

    # hvparams processing
    if self.op.hvparams:
      i_hvdict, hv_new = self._GetUpdatedParams(
                             instance.hvparams, self.op.hvparams,
                             cluster.hvparams[instance.hypervisor],
                             constants.HVS_PARAMETER_TYPES)
      # local check
      hypervisor.GetHypervisor(
        instance.hypervisor).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, be_new = self._GetUpdatedParams(
                             instance.beparams, self.op.beparams,
                             cluster.beparams[constants.PP_DEFAULT],
                             constants.BES_PARAMETER_TYPES)
      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)

      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")
        continue
      if nic_op != constants.DDM_ADD:
        # an existing nic
        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)))
        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, new_filled_nic_params = \
          self._GetUpdatedParams(old_nic_params, update_params_dict,
                                 cluster.nicparams[constants.PP_DEFAULT],
                                 constants.NICS_PARAMETER_TYPES)
      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)
      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')
      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')
        elif nic_mac in (constants.VALUE_AUTO, constants.VALUE_GENERATE):
          # otherwise generate the mac
          nic_dict['mac'] = self.cfg.GenerateMAC()
        else:
          # or validate/reserve the current one
          if self.cfg.IsMacInUse(nic_mac):
            raise errors.OpPrereqError("MAC address %s already in use"
                                       " in cluster" % nic_mac)

    # DISK processing
    if self.op.disks and instance.disk_template == constants.DT_DISKLESS:
      raise errors.OpPrereqError("Disk operations not supported for"
                                 " diskless instances")
    for disk_op, disk_dict 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")
        ins_l = self.rpc.call_instance_list([pnode], [instance.hypervisor])
        ins_l = ins_l[pnode]
        msg = ins_l.fail_msg
        if msg:
          raise errors.OpPrereqError("Can't contact node %s: %s" %
                                     (pnode, msg))
        if instance.name in ins_l.payload:
          raise errors.OpPrereqError("Instance is running, can't 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)
      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)))

    return

  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
    cluster = self.cluster
    # 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']))
    # 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_pnew:
          instance.nics[nic_op].nicparams = self.nic_pnew[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))

    self.cfg.Update(instance)

    return result


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 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 ExpandNames(self):
    self._ExpandAndLockInstance()
    # 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 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_NODE": self.op.target_node,
      "EXPORT_DO_SHUTDOWN": self.op.shutdown,
      }
    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 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)

    self.dst_node = self.cfg.GetNodeInfo(
      self.cfg.ExpandNodeName(self.op.target_node))

    if self.dst_node is None:
      # This is wrong node name, not a non-locked node
      raise errors.OpPrereqError("Wrong node name %s" % self.op.target_node)
    _CheckNodeOnline(self, self.dst_node.name)
    _CheckNodeNotDrained(self, self.dst_node.name)

    # instance disk type verification
    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")

  def Exec(self, feedback_fn):
    """Export an instance to an image in the cluster.

    """
    instance = self.instance
    dst_node = self.dst_node
    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)
      result.Raise("Could not shutdown instance %s on"
                   " node %s" % (instance.name, src_node))

    vgname = self.cfg.GetVGName()

    snap_disks = []

    # 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)

    # per-disk results
    dresults = []
    try:
      for idx, disk in enumerate(instance.disks):
        feedback_fn("Creating a snapshot of disk/%s on node %s" %
                    (idx, src_node))

        # result.payload will be a snapshot of an lvm leaf of the one we passed
        result = self.rpc.call_blockdev_snapshot(src_node, disk)
        msg = result.fail_msg
        if msg:
          self.LogWarning("Could not snapshot disk/%s on node %s: %s",
                          idx, src_node, msg)
          snap_disks.append(False)
        else:
          disk_id = (vgname, result.payload)
          new_dev = objects.Disk(dev_type=constants.LD_LV, size=disk.size,
                                 logical_id=disk_id, physical_id=disk_id,
                                 iv_name=disk.iv_name)
          snap_disks.append(new_dev)

    finally:
      if self.op.shutdown and instance.admin_up:
        feedback_fn("Starting instance %s" % instance.name)
        result = self.rpc.call_instance_start(src_node, instance, None, None)
        msg = result.fail_msg
        if msg:
          _ShutdownInstanceDisks(self, instance)
          raise errors.OpExecError("Could not start instance: %s" % msg)

    # TODO: check for size

    cluster_name = self.cfg.GetClusterName()
    for idx, dev in enumerate(snap_disks):
      feedback_fn("Exporting snapshot %s from %s to %s" %
                  (idx, src_node, dst_node.name))
      if dev:
        result = self.rpc.call_snapshot_export(src_node, dev, dst_node.name,
                                               instance, cluster_name, idx)
        msg = result.fail_msg
        if msg:
          self.LogWarning("Could not export disk/%s from node %s to"
                          " node %s: %s", idx, src_node, dst_node.name, msg)
          dresults.append(False)
        else:
          dresults.append(True)
        msg = self.rpc.call_blockdev_remove(src_node, dev).fail_msg
        if msg:
          self.LogWarning("Could not remove snapshot for disk/%d from node"
                          " %s: %s", idx, src_node, msg)
      else:
        dresults.append(False)

    feedback_fn("Finalizing export on %s" % dst_node.name)
    result = self.rpc.call_finalize_export(dst_node.name, instance, snap_disks)
    fin_resu = True
    msg = result.fail_msg
    if msg:
      self.LogWarning("Could not finalize export for instance %s"
                      " on node %s: %s", instance.name, dst_node.name, msg)
      fin_resu = False

    nodelist = self.cfg.GetNodeList()
    nodelist.remove(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 = 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)
    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):
  """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:
      name = self.cfg.ExpandNodeName(self.op.name)
      if name is None:
        raise errors.OpPrereqError("Invalid node name (%s)" %
                                   (self.op.name,))
      self.op.name = name
      self.needed_locks[locking.LEVEL_NODE] = name
    elif self.op.kind == constants.TAG_INSTANCE:
      name = self.cfg.ExpandInstanceName(self.op.name)
      if name is None:
        raise errors.OpPrereqError("Invalid instance name (%s)" %
                                   (self.op.name,))
      self.op.name = name
      self.needed_locks[locking.LEVEL_INSTANCE] = 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))


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))

  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))
    try:
      self.cfg.Update(self.target)
    except errors.ConfigurationError:
      raise errors.OpRetryError("There has been a modification to the"
                                " config file and the operation has been"
                                " aborted. Please retry.")


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)))

  def Exec(self, feedback_fn):
    """Remove the tag from the object.

    """
    for tag in self.op.tags:
      self.target.RemoveTag(tag)
    try:
      self.cfg.Update(self.target)
    except errors.ConfigurationError:
      raise errors.OpRetryError("There has been a modification to the"
                                " config file and the operation has been"
                                " aborted. Please retry.")


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

  """
  _ALLO_KEYS = [
    "mem_size", "disks", "disk_template",
    "os", "tags", "nics", "vcpus", "hypervisor",
    ]
  _RELO_KEYS = [
    "relocate_from",
    ]

  def __init__(self, cfg, rpc, mode, name, **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.name = name
    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
    # computed fields
    self.required_nodes = None
    # init result fields
    self.success = self.info = self.nodes = None
    if self.mode == constants.IALLOCATOR_MODE_ALLOC:
      keyset = self._ALLO_KEYS
    elif self.mode == constants.IALLOCATOR_MODE_RELOC:
      keyset = self._RELO_KEYS
    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()

  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

    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 = objects.FillDict(
            cluster_info.nicparams[constants.PP_DEFAULT],
            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.

    """
    data = self.in_data

    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 = {
      "type": "allocate",
      "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,
      }
    data["request"] = 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")

    if len(instance.secondary_nodes) != 1:
      raise errors.OpPrereqError("Instance has not exactly one secondary node")

    self.required_nodes = 1
    disk_sizes = [{'size': disk.size} for disk in instance.disks]
    disk_space = _ComputeDiskSize(instance.disk_template, disk_sizes)

    request = {
      "type": "relocate",
      "name": self.name,
      "disk_space_total": disk_space,
      "required_nodes": self.required_nodes,
      "relocate_from": self.relocate_from,
      }
    self.in_data["request"] = request

  def _BuildInputData(self):
    """Build input data structures.

    """
    self._ComputeClusterData()

    if self.mode == constants.IALLOCATOR_MODE_ALLOC:
      self._AddNewInstance()
    else:
      self._AddRelocateInstance()

    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")

    for key in "success", "info", "nodes":
      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["nodes"], list):
      raise errors.OpExecError("Can't parse iallocator results: 'nodes' 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)
      iname = self.cfg.ExpandInstanceName(self.op.name)
      if iname is not None:
        raise errors.OpPrereqError("Instance '%s' already in the cluster" %
                                   iname)
      if not isinstance(self.op.nics, list):
        raise errors.OpPrereqError("Invalid parameter 'nics'")
      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")
      if not isinstance(self.op.disks, list):
        raise errors.OpPrereqError("Invalid parameter 'disks'")
      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")
      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")
      fname = self.cfg.ExpandInstanceName(self.op.name)
      if fname is None:
        raise errors.OpPrereqError("Instance '%s' not found for relocation" %
                                   self.op.name)
      self.op.name = fname
      self.relocate_from = self.cfg.GetInstanceInfo(fname).secondary_nodes
    else:
      raise errors.OpPrereqError("Invalid test allocator mode '%s'" %
                                 self.op.mode)

    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")
    elif self.op.direction != constants.IALLOCATOR_DIR_IN:
      raise errors.OpPrereqError("Wrong allocator test '%s'" %
                                 self.op.direction)

  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,
                       )
    else:
      ial = IAllocator(self.cfg, self.rpc,
                       mode=self.op.mode,
                       name=self.op.name,
                       relocate_from=list(self.relocate_from),
                       )

    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