Allow instance MAC address to be set.

[ganeti-local] / lib / cmdlib.py

#
#

# Copyright (C) 2006, 2007 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 sha
import time
import tempfile
import re
import platform

from ganeti import rpc
from ganeti import ssh
from ganeti import logger
from ganeti import utils
from ganeti import errors
from ganeti import hypervisor
from ganeti import config
from ganeti import constants
from ganeti import objects
from ganeti import opcodes
from ganeti import ssconf

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

  Subclasses must follow these rules:
    - implement CheckPrereq which also fills in the opcode instance
      with all the fields (even if as None)
    - implement Exec
    - implement BuildHooksEnv
    - redefine HPATH and HTYPE
    - optionally redefine their run requirements (REQ_CLUSTER,
      REQ_MASTER); note that all commands require root permissions

  """
  HPATH = None
  HTYPE = None
  _OP_REQP = []
  REQ_CLUSTER = True
  REQ_MASTER = True

  def __init__(self, processor, op, cfg, sstore):
    """Constructor for LogicalUnit.

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

    """
    self.proc = processor
    self.op = op
    self.cfg = cfg
    self.sstore = sstore
    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)
    if self.REQ_CLUSTER:
      if not cfg.IsCluster():
        raise errors.OpPrereqError("Cluster not initialized yet,"
                                   " use 'gnt-cluster init' first.")
      if self.REQ_MASTER:
        master = sstore.GetMasterNode()
        if master != utils.HostInfo().name:
          raise errors.OpPrereqError("Commands must be run on the master"
                                     " node %s" % master)

  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; e.g. a short node name must be fully
    expanded after this method has successfully completed (so that
    hooks, logging, etc. work correctly).

    """
    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.

    """
    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.

    As for the node lists, the master should not be included in the
    them, as it will be added by the hooks runner in case this LU
    requires a cluster to run on (otherwise we don't have a node
    list). 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


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

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

    This is a no-op, since we don't run hooks.

    """
    return {}, [], []


def _AddHostToEtcHosts(hostname):
  """Wrapper around utils.SetEtcHostsEntry.

  """
  hi = utils.HostInfo(name=hostname)
  utils.SetEtcHostsEntry(constants.ETC_HOSTS, hi.ip, hi.name, [hi.ShortName()])


def _RemoveHostFromEtcHosts(hostname):
  """Wrapper around utils.RemoveEtcHostsEntry.

  """
  hi = utils.HostInfo(name=hostname)
  utils.RemoveEtcHostsEntry(constants.ETC_HOSTS, hi.name)
  utils.RemoveEtcHostsEntry(constants.ETC_HOSTS, hi.ShortName())


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

  Args:
    nodes: List of nodes (strings) or None for all

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

  if nodes:
    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)

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


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

  Args:
    instances: List of instances (strings) or None for all

  """
  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 = lu.cfg.GetInstanceList()
  return utils.NiceSort(wanted)


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

  Args:
    static: Static fields
    dynamic: Dynamic fields

  """
  static_fields = frozenset(static)
  dynamic_fields = frozenset(dynamic)

  all_fields = static_fields | dynamic_fields

  if not all_fields.issuperset(selected):
    raise errors.OpPrereqError("Unknown output fields selected: %s"
                               % ",".join(frozenset(selected).
                                          difference(all_fields)))


def _BuildInstanceHookEnv(name, primary_node, secondary_nodes, os_type, status,
                          memory, vcpus, nics):
  """Builds instance related env variables for hooks from single variables.

  Args:
    secondary_nodes: List of secondary nodes as strings
  """
  env = {
    "OP_TARGET": name,
    "INSTANCE_NAME": name,
    "INSTANCE_PRIMARY": primary_node,
    "INSTANCE_SECONDARIES": " ".join(secondary_nodes),
    "INSTANCE_OS_TYPE": os_type,
    "INSTANCE_STATUS": status,
    "INSTANCE_MEMORY": memory,
    "INSTANCE_VCPUS": vcpus,
  }

  if nics:
    nic_count = len(nics)
    for idx, (ip, bridge) in enumerate(nics):
      if ip is None:
        ip = ""
      env["INSTANCE_NIC%d_IP" % idx] = ip
      env["INSTANCE_NIC%d_BRIDGE" % idx] = bridge
  else:
    nic_count = 0

  env["INSTANCE_NIC_COUNT"] = nic_count

  return env


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

  Args:
    instance: objects.Instance object of instance
    override: dict of values to override
  """
  args = {
    'name': instance.name,
    'primary_node': instance.primary_node,
    'secondary_nodes': instance.secondary_nodes,
    'os_type': instance.os,
    'status': instance.os,
    'memory': instance.memory,
    'vcpus': instance.vcpus,
    'nics': [(nic.ip, nic.bridge) for nic in instance.nics],
  }
  if override:
    args.update(override)
  return _BuildInstanceHookEnv(**args)


def _UpdateKnownHosts(fullnode, ip, pubkey):
  """Ensure a node has a correct known_hosts entry.

  Args:
    fullnode - Fully qualified domain name of host. (str)
    ip       - IPv4 address of host (str)
    pubkey   - the public key of the cluster

  """
  if os.path.exists(constants.SSH_KNOWN_HOSTS_FILE):
    f = open(constants.SSH_KNOWN_HOSTS_FILE, 'r+')
  else:
    f = open(constants.SSH_KNOWN_HOSTS_FILE, 'w+')

  inthere = False

  save_lines = []
  add_lines = []
  removed = False

  for rawline in f:
    logger.Debug('read %s' % (repr(rawline),))

    parts = rawline.rstrip('\r\n').split()

    # Ignore unwanted lines
    if len(parts) >= 3 and not rawline.lstrip()[0] == '#':
      fields = parts[0].split(',')
      key = parts[2]

      haveall = True
      havesome = False
      for spec in [ ip, fullnode ]:
        if spec not in fields:
          haveall = False
        if spec in fields:
          havesome = True

      logger.Debug("key, pubkey = %s." % (repr((key, pubkey)),))
      if haveall and key == pubkey:
        inthere = True
        save_lines.append(rawline)
        logger.Debug("Keeping known_hosts '%s'." % (repr(rawline),))
        continue

      if havesome and (not haveall or key != pubkey):
        removed = True
        logger.Debug("Discarding known_hosts '%s'." % (repr(rawline),))
        continue

    save_lines.append(rawline)

  if not inthere:
    add_lines.append('%s,%s ssh-rsa %s\n' % (fullnode, ip, pubkey))
    logger.Debug("Adding known_hosts '%s'." % (repr(add_lines[-1]),))

  if removed:
    save_lines = save_lines + add_lines

    # Write a new file and replace old.
    fd, tmpname = tempfile.mkstemp('.tmp', 'known_hosts.',
                                   constants.DATA_DIR)
    newfile = os.fdopen(fd, 'w')
    try:
      newfile.write(''.join(save_lines))
    finally:
      newfile.close()
    logger.Debug("Wrote new known_hosts.")
    os.rename(tmpname, constants.SSH_KNOWN_HOSTS_FILE)

  elif add_lines:
    # Simply appending a new line will do the trick.
    f.seek(0, 2)
    for add in add_lines:
      f.write(add)

  f.close()


def _HasValidVG(vglist, vgname):
  """Checks if the volume group list is valid.

  A non-None return value means there's an error, and the return value
  is the error message.

  """
  vgsize = vglist.get(vgname, None)
  if vgsize is None:
    return "volume group '%s' missing" % vgname
  elif vgsize < 20480:
    return ("volume group '%s' too small (20480MiB required, %dMib found)" %
            (vgname, vgsize))
  return None


def _InitSSHSetup(node):
  """Setup the SSH configuration for the cluster.


  This generates a dsa keypair for root, adds the pub key to the
  permitted hosts and adds the hostkey to its own known hosts.

  Args:
    node: the name of this host as a fqdn

  """
  priv_key, pub_key, auth_keys = ssh.GetUserFiles(constants.GANETI_RUNAS)

  for name in priv_key, pub_key:
    if os.path.exists(name):
      utils.CreateBackup(name)
    utils.RemoveFile(name)

  result = utils.RunCmd(["ssh-keygen", "-t", "dsa",
                         "-f", priv_key,
                         "-q", "-N", ""])
  if result.failed:
    raise errors.OpExecError("Could not generate ssh keypair, error %s" %
                             result.output)

  f = open(pub_key, 'r')
  try:
    utils.AddAuthorizedKey(auth_keys, f.read(8192))
  finally:
    f.close()


def _InitGanetiServerSetup(ss):
  """Setup the necessary configuration for the initial node daemon.

  This creates the nodepass file containing the shared password for
  the cluster and also generates the SSL certificate.

  """
  # Create pseudo random password
  randpass = sha.new(os.urandom(64)).hexdigest()
  # and write it into sstore
  ss.SetKey(ss.SS_NODED_PASS, randpass)

  result = utils.RunCmd(["openssl", "req", "-new", "-newkey", "rsa:1024",
                         "-days", str(365*5), "-nodes", "-x509",
                         "-keyout", constants.SSL_CERT_FILE,
                         "-out", constants.SSL_CERT_FILE, "-batch"])
  if result.failed:
    raise errors.OpExecError("could not generate server ssl cert, command"
                             " %s had exitcode %s and error message %s" %
                             (result.cmd, result.exit_code, result.output))

  os.chmod(constants.SSL_CERT_FILE, 0400)

  result = utils.RunCmd([constants.NODE_INITD_SCRIPT, "restart"])

  if result.failed:
    raise errors.OpExecError("Could not start the node daemon, command %s"
                             " had exitcode %s and error %s" %
                             (result.cmd, result.exit_code, result.output))


def _CheckInstanceBridgesExist(instance):
  """Check that the brigdes needed by an instance exist.

  """
  # check bridges existance
  brlist = [nic.bridge for nic in instance.nics]
  if not rpc.call_bridges_exist(instance.primary_node, brlist):
    raise errors.OpPrereqError("one or more target bridges %s does not"
                               " exist on destination node '%s'" %
                               (brlist, instance.primary_node))


class LUInitCluster(LogicalUnit):
  """Initialise the cluster.

  """
  HPATH = "cluster-init"
  HTYPE = constants.HTYPE_CLUSTER
  _OP_REQP = ["cluster_name", "hypervisor_type", "vg_name", "mac_prefix",
              "def_bridge", "master_netdev"]
  REQ_CLUSTER = False

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

    Notes: Since we don't require a cluster, we must manually add
    ourselves in the post-run node list.

    """
    env = {"OP_TARGET": self.op.cluster_name}
    return env, [], [self.hostname.name]

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

    """
    if config.ConfigWriter.IsCluster():
      raise errors.OpPrereqError("Cluster is already initialised")

    if self.op.hypervisor_type == constants.HT_XEN_HVM31:
      if not os.path.exists(constants.VNC_PASSWORD_FILE):
        raise errors.OpPrereqError("Please prepare the cluster VNC"
                                   "password file %s" %
                                   constants.VNC_PASSWORD_FILE)

    self.hostname = hostname = utils.HostInfo()

    if hostname.ip.startswith("127."):
      raise errors.OpPrereqError("This host's IP resolves to the private"
                                 " range (%s). Please fix DNS or /etc/hosts." %
                                 (hostname.ip,))

    self.clustername = clustername = utils.HostInfo(self.op.cluster_name)

    if not utils.TcpPing(constants.LOCALHOST_IP_ADDRESS, hostname.ip,
                         constants.DEFAULT_NODED_PORT):
      raise errors.OpPrereqError("Inconsistency: this host's name resolves"
                                 " to %s,\nbut this ip address does not"
                                 " belong to this host."
                                 " Aborting." % hostname.ip)

    secondary_ip = getattr(self.op, "secondary_ip", None)
    if secondary_ip and not utils.IsValidIP(secondary_ip):
      raise errors.OpPrereqError("Invalid secondary ip given")
    if (secondary_ip and
        secondary_ip != hostname.ip and
        (not utils.TcpPing(constants.LOCALHOST_IP_ADDRESS, secondary_ip,
                           constants.DEFAULT_NODED_PORT))):
      raise errors.OpPrereqError("You gave %s as secondary IP,"
                                 " but it does not belong to this host." %
                                 secondary_ip)
    self.secondary_ip = secondary_ip

    # checks presence of the volume group given
    vgstatus = _HasValidVG(utils.ListVolumeGroups(), self.op.vg_name)

    if vgstatus:
      raise errors.OpPrereqError("Error: %s" % vgstatus)

    if not re.match("^[0-9a-z]{2}:[0-9a-z]{2}:[0-9a-z]{2}$",
                    self.op.mac_prefix):
      raise errors.OpPrereqError("Invalid mac prefix given '%s'" %
                                 self.op.mac_prefix)

    if self.op.hypervisor_type not in constants.HYPER_TYPES:
      raise errors.OpPrereqError("Invalid hypervisor type given '%s'" %
                                 self.op.hypervisor_type)

    result = utils.RunCmd(["ip", "link", "show", "dev", self.op.master_netdev])
    if result.failed:
      raise errors.OpPrereqError("Invalid master netdev given (%s): '%s'" %
                                 (self.op.master_netdev,
                                  result.output.strip()))

    if not (os.path.isfile(constants.NODE_INITD_SCRIPT) and
            os.access(constants.NODE_INITD_SCRIPT, os.X_OK)):
      raise errors.OpPrereqError("Init.d script '%s' missing or not"
                                 " executable." % constants.NODE_INITD_SCRIPT)

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

    """
    clustername = self.clustername
    hostname = self.hostname

    # set up the simple store
    self.sstore = ss = ssconf.SimpleStore()
    ss.SetKey(ss.SS_HYPERVISOR, self.op.hypervisor_type)
    ss.SetKey(ss.SS_MASTER_NODE, hostname.name)
    ss.SetKey(ss.SS_MASTER_IP, clustername.ip)
    ss.SetKey(ss.SS_MASTER_NETDEV, self.op.master_netdev)
    ss.SetKey(ss.SS_CLUSTER_NAME, clustername.name)

    # set up the inter-node password and certificate
    _InitGanetiServerSetup(ss)

    # start the master ip
    rpc.call_node_start_master(hostname.name)

    # set up ssh config and /etc/hosts
    f = open(constants.SSH_HOST_RSA_PUB, 'r')
    try:
      sshline = f.read()
    finally:
      f.close()
    sshkey = sshline.split(" ")[1]

    _AddHostToEtcHosts(hostname.name)

    _UpdateKnownHosts(hostname.name, hostname.ip, sshkey)

    _InitSSHSetup(hostname.name)

    # init of cluster config file
    self.cfg = cfgw = config.ConfigWriter()
    cfgw.InitConfig(hostname.name, hostname.ip, self.secondary_ip,
                    sshkey, self.op.mac_prefix,
                    self.op.vg_name, self.op.def_bridge)


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

  """
  _OP_REQP = []

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

    This checks whether the cluster is empty.

    Any errors are signalled by raising errors.OpPrereqError.

    """
    master = self.sstore.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.sstore.GetMasterNode()
    priv_key, pub_key, _ = ssh.GetUserFiles(constants.GANETI_RUNAS)
    utils.CreateBackup(priv_key)
    utils.CreateBackup(pub_key)
    rpc.call_node_leave_cluster(master)


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

  """
  _OP_REQP = []

  def _VerifyNode(self, node, file_list, local_cksum, vglist, node_result,
                  remote_version, feedback_fn):
    """Run multiple tests against a node.

    Test list:
      - compares ganeti version
      - checks vg existance and size > 20G
      - checks config file checksum
      - checks ssh to other nodes

    Args:
      node: name of the node to check
      file_list: required list of files
      local_cksum: dictionary of local files and their checksums

    """
    # compares ganeti version
    local_version = constants.PROTOCOL_VERSION
    if not remote_version:
      feedback_fn(" - ERROR: connection to %s failed" % (node))
      return True

    if local_version != remote_version:
      feedback_fn("  - ERROR: sw version mismatch: master %s, node(%s) %s" %
                      (local_version, node, remote_version))
      return True

    # checks vg existance and size > 20G

    bad = False
    if not vglist:
      feedback_fn("  - ERROR: unable to check volume groups on node %s." %
                      (node,))
      bad = True
    else:
      vgstatus = _HasValidVG(vglist, self.cfg.GetVGName())
      if vgstatus:
        feedback_fn("  - ERROR: %s on node %s" % (vgstatus, node))
        bad = True

    # checks config file checksum
    # checks ssh to any

    if 'filelist' not in node_result:
      bad = True
      feedback_fn("  - ERROR: node hasn't returned file checksum data")
    else:
      remote_cksum = node_result['filelist']
      for file_name in file_list:
        if file_name not in remote_cksum:
          bad = True
          feedback_fn("  - ERROR: file '%s' missing" % file_name)
        elif remote_cksum[file_name] != local_cksum[file_name]:
          bad = True
          feedback_fn("  - ERROR: file '%s' has wrong checksum" % file_name)

    if 'nodelist' not in node_result:
      bad = True
      feedback_fn("  - ERROR: node hasn't returned node connectivity data")
    else:
      if node_result['nodelist']:
        bad = True
        for node in node_result['nodelist']:
          feedback_fn("  - ERROR: communication with node '%s': %s" %
                          (node, node_result['nodelist'][node]))
    hyp_result = node_result.get('hypervisor', None)
    if hyp_result is not None:
      feedback_fn("  - ERROR: hypervisor verify failure: '%s'" % hyp_result)
    return bad

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

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

    """
    bad = False

    instancelist = self.cfg.GetInstanceList()
    if not instance in instancelist:
      feedback_fn("  - ERROR: instance %s not in instance list %s" %
                      (instance, instancelist))
      bad = True

    instanceconfig = self.cfg.GetInstanceInfo(instance)
    node_current = instanceconfig.primary_node

    node_vol_should = {}
    instanceconfig.MapLVsByNode(node_vol_should)

    for node in node_vol_should:
      for volume in node_vol_should[node]:
        if node not in node_vol_is or volume not in node_vol_is[node]:
          feedback_fn("  - ERROR: volume %s missing on node %s" %
                          (volume, node))
          bad = True

    if not instanceconfig.status == 'down':
      if not instance in node_instance[node_current]:
        feedback_fn("  - ERROR: instance %s not running on node %s" %
                        (instance, node_current))
        bad = True

    for node in node_instance:
      if (not node == node_current):
        if instance in node_instance[node]:
          feedback_fn("  - ERROR: instance %s should not run on node %s" %
                          (instance, node))
          bad = True

    return bad

  def _VerifyOrphanVolumes(self, node_vol_should, node_vol_is, feedback_fn):
    """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.

    """
    bad = False

    for node in node_vol_is:
      for volume in node_vol_is[node]:
        if node not in node_vol_should or volume not in node_vol_should[node]:
          feedback_fn("  - ERROR: volume %s on node %s should not exist" %
                      (volume, node))
          bad = True
    return bad

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

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

    """
    bad = False
    for node in node_instance:
      for runninginstance in node_instance[node]:
        if runninginstance not in instancelist:
          feedback_fn("  - ERROR: instance %s on node %s should not exist" %
                          (runninginstance, node))
          bad = True
    return bad

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

    This has no prerequisites.

    """
    pass

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

    """
    bad = False
    feedback_fn("* Verifying global settings")
    for msg in self.cfg.VerifyConfig():
      feedback_fn("  - ERROR: %s" % msg)

    vg_name = self.cfg.GetVGName()
    nodelist = utils.NiceSort(self.cfg.GetNodeList())
    instancelist = utils.NiceSort(self.cfg.GetInstanceList())
    node_volume = {}
    node_instance = {}

    # FIXME: verify OS list
    # do local checksums
    file_names = list(self.sstore.GetFileList())
    file_names.append(constants.SSL_CERT_FILE)
    file_names.append(constants.CLUSTER_CONF_FILE)
    local_checksums = utils.FingerprintFiles(file_names)

    feedback_fn("* Gathering data (%d nodes)" % len(nodelist))
    all_volumeinfo = rpc.call_volume_list(nodelist, vg_name)
    all_instanceinfo = rpc.call_instance_list(nodelist)
    all_vglist = rpc.call_vg_list(nodelist)
    node_verify_param = {
      'filelist': file_names,
      'nodelist': nodelist,
      'hypervisor': None,
      }
    all_nvinfo = rpc.call_node_verify(nodelist, node_verify_param)
    all_rversion = rpc.call_version(nodelist)

    for node in nodelist:
      feedback_fn("* Verifying node %s" % node)
      result = self._VerifyNode(node, file_names, local_checksums,
                                all_vglist[node], all_nvinfo[node],
                                all_rversion[node], feedback_fn)
      bad = bad or result

      # node_volume
      volumeinfo = all_volumeinfo[node]

      if type(volumeinfo) != dict:
        feedback_fn("  - ERROR: connection to %s failed" % (node,))
        bad = True
        continue

      node_volume[node] = volumeinfo

      # node_instance
      nodeinstance = all_instanceinfo[node]
      if type(nodeinstance) != list:
        feedback_fn("  - ERROR: connection to %s failed" % (node,))
        bad = True
        continue

      node_instance[node] = nodeinstance

    node_vol_should = {}

    for instance in instancelist:
      feedback_fn("* Verifying instance %s" % instance)
      result =  self._VerifyInstance(instance, node_volume, node_instance,
                                     feedback_fn)
      bad = bad or result

      inst_config = self.cfg.GetInstanceInfo(instance)

      inst_config.MapLVsByNode(node_vol_should)

    feedback_fn("* Verifying orphan volumes")
    result = self._VerifyOrphanVolumes(node_vol_should, node_volume,
                                       feedback_fn)
    bad = bad or result

    feedback_fn("* Verifying remaining instances")
    result = self._VerifyOrphanInstances(instancelist, node_instance,
                                         feedback_fn)
    bad = bad or result

    return int(bad)


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

  """
  _OP_REQP = []

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

    This has no prerequisites.

    """
    pass

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

    """
    result = res_nodes, res_instances = [], []

    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 (inst.status != "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 = rpc.call_volume_list(nodes, vg_name)

    to_act = set()
    for node in nodes:
      # node_volume
      lvs = node_lvs[node]

      if not isinstance(lvs, dict):
        logger.Info("connection to node %s failed or invalid data returned" %
                    (node,))
        res_nodes.append(node)
        continue

      for lv_name, (_, lv_inactive, lv_online) in lvs.iteritems():
        if not lv_online:
          inst = nv_dict.get((node, lv_name), None)
          if inst is not None and inst.name not in res_instances:
            res_instances.append(inst.name)

    return result


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.op.sstore.GetClusterName(),
      "NEW_NAME": self.op.name,
      }
    mn = self.sstore.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.sstore.GetClusterName()
    old_ip = self.sstore.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:
      result = utils.RunCmd(["fping", "-q", new_ip])
      if not result.failed:
        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
    ss = self.sstore

    # shutdown the master IP
    master = ss.GetMasterNode()
    if not rpc.call_node_stop_master(master):
      raise errors.OpExecError("Could not disable the master role")

    try:
      # modify the sstore
      ss.SetKey(ss.SS_MASTER_IP, ip)
      ss.SetKey(ss.SS_CLUSTER_NAME, clustername)

      # Distribute updated ss config to all nodes
      myself = self.cfg.GetNodeInfo(master)
      dist_nodes = self.cfg.GetNodeList()
      if myself.name in dist_nodes:
        dist_nodes.remove(myself.name)

      logger.Debug("Copying updated ssconf data to all nodes")
      for keyname in [ss.SS_CLUSTER_NAME, ss.SS_MASTER_IP]:
        fname = ss.KeyToFilename(keyname)
        result = rpc.call_upload_file(dist_nodes, fname)
        for to_node in dist_nodes:
          if not result[to_node]:
            logger.Error("copy of file %s to node %s failed" %
                         (fname, to_node))
    finally:
      if not rpc.call_node_start_master(master):
        logger.Error("Could not re-enable the master role on the master,"
                     " please restart manually.")


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

  """
  if not instance.disks:
    return True

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

  node = instance.primary_node

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

  retries = 0
  while True:
    max_time = 0
    done = True
    cumul_degraded = False
    rstats = rpc.call_blockdev_getmirrorstatus(node, instance.disks)
    if not rstats:
      proc.LogWarning("Can't get any data from node %s" % node)
      retries += 1
      if retries >= 10:
        raise errors.RemoteError("Can't contact node %s for mirror data,"
                                 " aborting." % node)
      time.sleep(6)
      continue
    retries = 0
    for i in range(len(rstats)):
      mstat = rstats[i]
      if mstat is None:
        proc.LogWarning("Can't compute data for node %s/%s" %
                        (node, instance.disks[i].iv_name))
        continue
      # we ignore the ldisk parameter
      perc_done, est_time, is_degraded, _ = mstat
      cumul_degraded = cumul_degraded or (is_degraded and perc_done is None)
      if perc_done is not None:
        done = False
        if est_time is not None:
          rem_time = "%d estimated seconds remaining" % est_time
          max_time = est_time
        else:
          rem_time = "no time estimate"
        proc.LogInfo("- device %s: %5.2f%% done, %s" %
                     (instance.disks[i].iv_name, perc_done, rem_time))
    if done or oneshot:
      break

    if unlock:
      utils.Unlock('cmd')
    try:
      time.sleep(min(60, max_time))
    finally:
      if unlock:
        utils.Lock('cmd')

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


def _CheckDiskConsistency(cfgw, 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).

  """
  cfgw.SetDiskID(dev, node)
  if ldisk:
    idx = 6
  else:
    idx = 5

  result = True
  if on_primary or dev.AssembleOnSecondary():
    rstats = rpc.call_blockdev_find(node, dev)
    if not rstats:
      logger.ToStderr("Can't get any data from node %s" % node)
      result = False
    else:
      result = result and (not rstats[idx])
  if dev.children:
    for child in dev.children:
      result = result and _CheckDiskConsistency(cfgw, child, node, on_primary)

  return result


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

  """
  _OP_REQP = []

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

    This always succeeds, since this is a pure query LU.

    """
    return

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

    """
    node_list = self.cfg.GetNodeList()
    node_data = rpc.call_os_diagnose(node_list)
    if node_data == False:
      raise errors.OpExecError("Can't gather the list of OSes")
    return node_data


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 not allows itself to run.

    """
    env = {
      "OP_TARGET": self.op.node_name,
      "NODE_NAME": self.op.node_name,
      }
    all_nodes = self.cfg.GetNodeList()
    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 signalled 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.sstore.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 == instance.primary_node:
        raise errors.OpPrereqError("Instance %s still running on the node,"
                                   " please remove first." % instance_name)
      if node.name in instance.secondary_nodes:
        raise errors.OpPrereqError("Instance %s has node as a secondary,"
                                   " 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
    logger.Info("stopping the node daemon and removing configs from node %s" %
                node.name)

    rpc.call_node_leave_cluster(node.name)

    ssh.SSHCall(node.name, 'root', "%s stop" % constants.NODE_INITD_SCRIPT)

    logger.Info("Removing node %s from config" % node.name)

    self.cfg.RemoveNode(node.name)

    _RemoveHostFromEtcHosts(node.name)


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

  """
  _OP_REQP = ["output_fields", "names"]

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

    This checks that the fields required are valid output fields.

    """
    self.dynamic_fields = frozenset(["dtotal", "dfree",
                                     "mtotal", "mnode", "mfree",
                                     "bootid"])

    _CheckOutputFields(static=["name", "pinst_cnt", "sinst_cnt",
                               "pinst_list", "sinst_list",
                               "pip", "sip"],
                       dynamic=self.dynamic_fields,
                       selected=self.op.output_fields)

    self.wanted = _GetWantedNodes(self, self.op.names)

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

    """
    nodenames = self.wanted
    nodelist = [self.cfg.GetNodeInfo(name) for name in nodenames]

    # begin data gathering

    if self.dynamic_fields.intersection(self.op.output_fields):
      live_data = {}
      node_data = rpc.call_node_info(nodenames, self.cfg.GetVGName())
      for name in nodenames:
        nodeinfo = node_data.get(name, None)
        if nodeinfo:
          live_data[name] = {
            "mtotal": utils.TryConvert(int, nodeinfo['memory_total']),
            "mnode": utils.TryConvert(int, nodeinfo['memory_dom0']),
            "mfree": utils.TryConvert(int, nodeinfo['memory_free']),
            "dtotal": utils.TryConvert(int, nodeinfo['vg_size']),
            "dfree": utils.TryConvert(int, nodeinfo['vg_free']),
            "bootid": nodeinfo['bootid'],
            }
        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)

    # end data gathering

    output = []
    for node in nodelist:
      node_output = []
      for field in self.op.output_fields:
        if field == "name":
          val = node.name
        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 in self.dynamic_fields:
          val = live_data[node.name].get(field, None)
        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"]

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

    This checks that the fields required are valid output fields.

    """
    self.nodes = _GetWantedNodes(self, self.op.nodes)

    _CheckOutputFields(static=["node"],
                       dynamic=["phys", "vg", "name", "size", "instance"],
                       selected=self.op.output_fields)


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

    """
    nodenames = self.nodes
    volumes = 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:
      if node not in volumes or not volumes[node]:
        continue

      node_vols = volumes[node][:]
      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 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 signalled 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 node in node_list:
      raise errors.OpPrereqError("Node %s is already in the configuration"
                                 % node)

    for existing_node_name in node_list:
      existing_node = cfg.GetNodeInfo(existing_node_name)
      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.sstore.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 reachablity
    if not utils.TcpPing(utils.HostInfo().name,
                         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(myself.secondary_ip,
                           secondary_ip,
                           constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("Node secondary ip not reachable by TCP"
                                   " based ping to noded port")

    self.new_node = objects.Node(name=node,
                                 primary_ip=primary_ip,
                                 secondary_ip=secondary_ip)

    if self.sstore.GetHypervisorType() == constants.HT_XEN_HVM31:
      if not os.path.exists(constants.VNC_PASSWORD_FILE):
        raise errors.OpPrereqError("Cluster VNC password file %s missing" %
                                   constants.VNC_PASSWORD_FILE)

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

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

    # set up inter-node password and certificate and restarts the node daemon
    gntpass = self.sstore.GetNodeDaemonPassword()
    if not re.match('^[a-zA-Z0-9.]{1,64}$', gntpass):
      raise errors.OpExecError("ganeti password corruption detected")
    f = open(constants.SSL_CERT_FILE)
    try:
      gntpem = f.read(8192)
    finally:
      f.close()
    # in the base64 pem encoding, neither '!' nor '.' are valid chars,
    # so we use this to detect an invalid certificate; as long as the
    # cert doesn't contain this, the here-document will be correctly
    # parsed by the shell sequence below
    if re.search('^!EOF\.', gntpem, re.MULTILINE):
      raise errors.OpExecError("invalid PEM encoding in the SSL certificate")
    if not gntpem.endswith("\n"):
      raise errors.OpExecError("PEM must end with newline")
    logger.Info("copy cluster pass to %s and starting the node daemon" % node)

    # and then connect with ssh to set password and start ganeti-noded
    # note that all the below variables are sanitized at this point,
    # either by being constants or by the checks above
    ss = self.sstore
    mycommand = ("umask 077 && "
                 "echo '%s' > '%s' && "
                 "cat > '%s' << '!EOF.' && \n"
                 "%s!EOF.\n%s restart" %
                 (gntpass, ss.KeyToFilename(ss.SS_NODED_PASS),
                  constants.SSL_CERT_FILE, gntpem,
                  constants.NODE_INITD_SCRIPT))

    result = ssh.SSHCall(node, 'root', mycommand, batch=False, ask_key=True)
    if result.failed:
      raise errors.OpExecError("Remote command on node %s, error: %s,"
                               " output: %s" %
                               (node, result.fail_reason, result.output))

    # check connectivity
    time.sleep(4)

    result = rpc.call_version([node])[node]
    if result:
      if constants.PROTOCOL_VERSION == result:
        logger.Info("communication to node %s fine, sw version %s match" %
                    (node, result))
      else:
        raise errors.OpExecError("Version mismatch master version %s,"
                                 " node version %s" %
                                 (constants.PROTOCOL_VERSION, result))
    else:
      raise errors.OpExecError("Cannot get version from the new node")

    # setup ssh on node
    logger.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:
      f = open(i, 'r')
      try:
        keyarray.append(f.read())
      finally:
        f.close()

    result = rpc.call_node_add(node, keyarray[0], keyarray[1], keyarray[2],
                               keyarray[3], keyarray[4], keyarray[5])

    if not result:
      raise errors.OpExecError("Cannot transfer ssh keys to the new node")

    # Add node to our /etc/hosts, and add key to known_hosts
    _AddHostToEtcHosts(new_node.name)

    _UpdateKnownHosts(new_node.name, new_node.primary_ip,
                      self.cfg.GetHostKey())

    if new_node.secondary_ip != new_node.primary_ip:
      if not rpc.call_node_tcp_ping(new_node.name,
                                    constants.LOCALHOST_IP_ADDRESS,
                                    new_node.secondary_ip,
                                    constants.DEFAULT_NODED_PORT,
                                    10, False):
        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)

    success, msg = ssh.VerifyNodeHostname(node)
    if not success:
      raise errors.OpExecError("Node '%s' claims it has a different hostname"
                               " than the one the resolver gives: %s."
                               " Please fix and re-run this command." %
                               (node, msg))

    # Distribute updated /etc/hosts and known_hosts to all nodes,
    # including the node just added
    myself = self.cfg.GetNodeInfo(self.sstore.GetMasterNode())
    dist_nodes = self.cfg.GetNodeList() + [node]
    if myself.name in dist_nodes:
      dist_nodes.remove(myself.name)

    logger.Debug("Copying hosts and known_hosts to all nodes")
    for fname in ("/etc/hosts", constants.SSH_KNOWN_HOSTS_FILE):
      result = rpc.call_upload_file(dist_nodes, fname)
      for to_node in dist_nodes:
        if not result[to_node]:
          logger.Error("copy of file %s to node %s failed" %
                       (fname, to_node))

    to_copy = ss.GetFileList()
    if self.sstore.GetHypervisorType() == constants.HT_XEN_HVM31:
      to_copy.append(constants.VNC_PASSWORD_FILE)
    for fname in to_copy:
      if not ssh.CopyFileToNode(node, fname):
        logger.Error("could not copy file %s to node %s" % (fname, node))

    logger.Info("adding node %s to cluster.conf" % node)
    self.cfg.AddNode(new_node)


class LUMasterFailover(LogicalUnit):
  """Failover the master node to the current node.

  This is a special LU in that it must run on a non-master node.

  """
  HPATH = "master-failover"
  HTYPE = constants.HTYPE_CLUSTER
  REQ_MASTER = False
  _OP_REQP = []

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

    This will run on the new master only in the pre phase, and on all
    the nodes in the post phase.

    """
    env = {
      "OP_TARGET": self.new_master,
      "NEW_MASTER": self.new_master,
      "OLD_MASTER": self.old_master,
      }
    return env, [self.new_master], self.cfg.GetNodeList()

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

    This checks that we are not already the master.

    """
    self.new_master = utils.HostInfo().name
    self.old_master = self.sstore.GetMasterNode()

    if self.old_master == self.new_master:
      raise errors.OpPrereqError("This commands must be run on the node"
                                 " where you want the new master to be."
                                 " %s is already the master" %
                                 self.old_master)

  def Exec(self, feedback_fn):
    """Failover the master node.

    This command, when run on a non-master node, will cause the current
    master to cease being master, and the non-master to become new
    master.

    """
    #TODO: do not rely on gethostname returning the FQDN
    logger.Info("setting master to %s, old master: %s" %
                (self.new_master, self.old_master))

    if not rpc.call_node_stop_master(self.old_master):
      logger.Error("could disable the master role on the old master"
                   " %s, please disable manually" % self.old_master)

    ss = self.sstore
    ss.SetKey(ss.SS_MASTER_NODE, self.new_master)
    if not rpc.call_upload_file(self.cfg.GetNodeList(),
                                ss.KeyToFilename(ss.SS_MASTER_NODE)):
      logger.Error("could not distribute the new simple store master file"
                   " to the other nodes, please check.")

    if not rpc.call_node_start_master(self.new_master):
      logger.Error("could not start the master role on the new master"
                   " %s, please check" % self.new_master)
      feedback_fn("Error in activating the master IP on the new master,"
                  " please fix manually.")



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

  """
  _OP_REQP = []
  REQ_MASTER = False

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

    """
    pass

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

    """
    result = {
      "name": self.sstore.GetClusterName(),
      "software_version": constants.RELEASE_VERSION,
      "protocol_version": constants.PROTOCOL_VERSION,
      "config_version": constants.CONFIG_VERSION,
      "os_api_version": constants.OS_API_VERSION,
      "export_version": constants.EXPORT_VERSION,
      "master": self.sstore.GetMasterNode(),
      "architecture": (platform.architecture()[0], platform.machine()),
      }

    return result


class LUClusterCopyFile(NoHooksLU):
  """Copy file to cluster.

  """
  _OP_REQP = ["nodes", "filename"]

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

    It should check that the named file exists and that the given list
    of nodes is valid.

    """
    if not os.path.exists(self.op.filename):
      raise errors.OpPrereqError("No such filename '%s'" % self.op.filename)

    self.nodes = _GetWantedNodes(self, self.op.nodes)

  def Exec(self, feedback_fn):
    """Copy a file from master to some nodes.

    Args:
      opts - class with options as members
      args - list containing a single element, the file name
    Opts used:
      nodes - list containing the name of target nodes; if empty, all nodes

    """
    filename = self.op.filename

    myname = utils.HostInfo().name

    for node in self.nodes:
      if node == myname:
        continue
      if not ssh.CopyFileToNode(node, filename):
        logger.Error("Copy of file %s to node %s failed" % (filename, node))


class LUDumpClusterConfig(NoHooksLU):
  """Return a text-representation of the cluster-config.

  """
  _OP_REQP = []

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

    """
    pass

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

    """
    return self.cfg.DumpConfig()


class LURunClusterCommand(NoHooksLU):
  """Run a command on some nodes.

  """
  _OP_REQP = ["command", "nodes"]

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

    It checks that the given list of nodes is valid.

    """
    self.nodes = _GetWantedNodes(self, self.op.nodes)

  def Exec(self, feedback_fn):
    """Run a command on some nodes.

    """
    data = []
    for node in self.nodes:
      result = ssh.SSHCall(node, "root", self.op.command)
      data.append((node, result.output, result.exit_code))

    return data


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

  """
  _OP_REQP = ["instance_name"]

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance


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

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

    return disks_info


def _AssembleInstanceDisks(instance, cfg, ignore_secondaries=False):
  """Prepare the block devices for an instance.

  This sets up the block devices on all nodes.

  Args:
    instance: a ganeti.objects.Instance object
    ignore_secondaries: if true, errors on secondary nodes won't result
                        in an error return from the function

  Returns:
    false if the operation failed
    list of (host, instance_visible_name, node_visible_name) if the operation
         suceeded with the mapping from node devices to instance devices
  """
  device_info = []
  disks_ok = True
  for inst_disk in instance.disks:
    master_result = None
    for node, node_disk in inst_disk.ComputeNodeTree(instance.primary_node):
      cfg.SetDiskID(node_disk, node)
      is_primary = node == instance.primary_node
      result = rpc.call_blockdev_assemble(node, node_disk,
                                          instance.name, is_primary)
      if not result:
        logger.Error("could not prepare block device %s on node %s"
                     " (is_primary=%s)" %
                     (inst_disk.iv_name, node, is_primary))
        if is_primary or not ignore_secondaries:
          disks_ok = False
      if is_primary:
        master_result = result
    device_info.append((instance.primary_node, inst_disk.iv_name,
                        master_result))

  # 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:
    cfg.SetDiskID(disk, instance.primary_node)

  return disks_ok, device_info


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

  """
  disks_ok, dummy = _AssembleInstanceDisks(instance, cfg,
                                           ignore_secondaries=force)
  if not disks_ok:
    _ShutdownInstanceDisks(instance, cfg)
    if force is not None and not force:
      logger.Error("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"]

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

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

    """
    instance = self.instance
    ins_l = rpc.call_instance_list([instance.primary_node])
    ins_l = ins_l[instance.primary_node]
    if not type(ins_l) is list:
      raise errors.OpExecError("Can't contact node '%s'" %
                               instance.primary_node)

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

    _ShutdownInstanceDisks(instance, self.cfg)


def _ShutdownInstanceDisks(instance, cfg, 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.

  """
  result = True
  for disk in instance.disks:
    for node, top_disk in disk.ComputeNodeTree(instance.primary_node):
      cfg.SetDiskID(top_disk, node)
      if not rpc.call_blockdev_shutdown(node, top_disk):
        logger.Error("could not shutdown block device %s on node %s" %
                     (disk.iv_name, node))
        if not ignore_primary or node != instance.primary_node:
          result = False
  return result


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

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

  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.instance))
    nl = ([self.sstore.GetMasterNode(), self.instance.primary_node] +
          list(self.instance.secondary_nodes))
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)

    # check bridges existance
    _CheckInstanceBridgesExist(instance)

    self.instance = instance
    self.op.instance_name = instance.name

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

    """
    instance = self.instance
    force = self.op.force
    extra_args = getattr(self.op, "extra_args", "")

    node_current = instance.primary_node

    nodeinfo = rpc.call_node_info([node_current], self.cfg.GetVGName())
    if not nodeinfo:
      raise errors.OpExecError("Could not contact node %s for infos" %
                               (node_current))

    freememory = nodeinfo[node_current]['memory_free']
    memory = instance.memory
    if memory > freememory:
      raise errors.OpExecError("Not enough memory to start instance"
                               " %s on node %s"
                               " needed %s MiB, available %s MiB" %
                               (instance.name, node_current, memory,
                                freememory))

    _StartInstanceDisks(self.cfg, instance, force)

    if not rpc.call_instance_start(node_current, instance, extra_args):
      _ShutdownInstanceDisks(instance, self.cfg)
      raise errors.OpExecError("Could not start instance")

    self.cfg.MarkInstanceUp(instance.name)


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

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

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

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

    """
    env = {
      "IGNORE_SECONDARIES": self.op.ignore_secondaries,
      }
    env.update(_BuildInstanceHookEnvByObject(self.instance))
    nl = ([self.sstore.GetMasterNode(), self.instance.primary_node] +
          list(self.instance.secondary_nodes))
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)

    # check bridges existance
    _CheckInstanceBridgesExist(instance)

    self.instance = instance
    self.op.instance_name = instance.name

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

    """
    instance = self.instance
    ignore_secondaries = self.op.ignore_secondaries
    reboot_type = self.op.reboot_type
    extra_args = getattr(self.op, "extra_args", "")

    node_current = instance.primary_node

    if 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))

    if reboot_type in [constants.INSTANCE_REBOOT_SOFT,
                       constants.INSTANCE_REBOOT_HARD]:
      if not rpc.call_instance_reboot(node_current, instance,
                                      reboot_type, extra_args):
        raise errors.OpExecError("Could not reboot instance")
    else:
      if not rpc.call_instance_shutdown(node_current, instance):
        raise errors.OpExecError("could not shutdown instance for full reboot")
      _ShutdownInstanceDisks(instance, self.cfg)
      _StartInstanceDisks(self.cfg, instance, ignore_secondaries)
      if not rpc.call_instance_start(node_current, instance, extra_args):
        _ShutdownInstanceDisks(instance, self.cfg)
        raise errors.OpExecError("Could not start instance for full reboot")

    self.cfg.MarkInstanceUp(instance.name)


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

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

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

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

    """
    env = _BuildInstanceHookEnvByObject(self.instance)
    nl = ([self.sstore.GetMasterNode(), self.instance.primary_node] +
          list(self.instance.secondary_nodes))
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

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

    """
    instance = self.instance
    node_current = instance.primary_node
    if not rpc.call_instance_shutdown(node_current, instance):
      logger.Error("could not shutdown instance")

    self.cfg.MarkInstanceDown(instance.name)
    _ShutdownInstanceDisks(instance, self.cfg)


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

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

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

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

    """
    env = _BuildInstanceHookEnvByObject(self.instance)
    nl = ([self.sstore.GetMasterNode(), self.instance.primary_node] +
          list(self.instance.secondary_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)
    if instance.disk_template == constants.DT_DISKLESS:
      raise errors.OpPrereqError("Instance '%s' has no disks" %
                                 self.op.instance_name)
    if instance.status != "down":
      raise errors.OpPrereqError("Instance '%s' is marked to be up" %
                                 self.op.instance_name)
    remote_info = rpc.call_instance_info(instance.primary_node, instance.name)
    if remote_info:
      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)
      os_obj = rpc.call_os_get(pnode.name, self.op.os_type)
      if not os_obj:
        raise errors.OpPrereqError("OS '%s' not in supported OS list for"
                                   " primary node"  % self.op.os_type)

    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.AddInstance(inst)

    _StartInstanceDisks(self.cfg, inst, None)
    try:
      feedback_fn("Running the instance OS create scripts...")
      if not rpc.call_instance_os_add(inst.primary_node, inst, "sda", "sdb"):
        raise errors.OpExecError("Could not install OS for instance %s"
                                 " on node %s" %
                                 (inst.name, inst.primary_node))
    finally:
      _ShutdownInstanceDisks(inst, self.cfg)


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.instance)
    env["INSTANCE_NEW_NAME"] = self.op.new_name
    nl = ([self.sstore.GetMasterNode(), self.instance.primary_node] +
          list(self.instance.secondary_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)
    if instance.status != "down":
      raise errors.OpPrereqError("Instance '%s' is marked to be up" %
                                 self.op.instance_name)
    remote_info = rpc.call_instance_info(instance.primary_node, instance.name)
    if remote_info:
      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
    if not getattr(self.op, "ignore_ip", False):
      command = ["fping", "-q", name_info.ip]
      result = utils.RunCmd(command)
      if not result.failed:
        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

    self.cfg.RenameInstance(inst.name, self.op.new_name)

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

    _StartInstanceDisks(self.cfg, inst, None)
    try:
      if not rpc.call_instance_run_rename(inst.primary_node, inst, old_name,
                                          "sda", "sdb"):
        msg = ("Could run OS rename script for instance %s on node %s (but the"
               " instance has been renamed in Ganeti)" %
               (inst.name, inst.primary_node))
        logger.Error(msg)
    finally:
      _ShutdownInstanceDisks(inst, self.cfg)


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

  """
  HPATH = "instance-remove"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name"]

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

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

    """
    env = _BuildInstanceHookEnvByObject(self.instance)
    nl = [self.sstore.GetMasterNode()]
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

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

    """
    instance = self.instance
    logger.Info("shutting down instance %s on node %s" %
                (instance.name, instance.primary_node))

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

    logger.Info("removing block devices for instance %s" % instance.name)

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

    logger.Info("removing instance %s out of cluster config" % instance.name)

    self.cfg.RemoveInstance(instance.name)


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

  """
  _OP_REQP = ["output_fields", "names"]

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

    This checks that the fields required are valid output fields.

    """
    self.dynamic_fields = frozenset(["oper_state", "oper_ram"])
    _CheckOutputFields(static=["name", "os", "pnode", "snodes",
                               "admin_state", "admin_ram",
                               "disk_template", "ip", "mac", "bridge",
                               "sda_size", "sdb_size"],
                       dynamic=self.dynamic_fields,
                       selected=self.op.output_fields)

    self.wanted = _GetWantedInstances(self, self.op.names)

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

    """
    instance_names = self.wanted
    instance_list = [self.cfg.GetInstanceInfo(iname) for iname
                     in instance_names]

    # begin data gathering

    nodes = frozenset([inst.primary_node for inst in instance_list])

    bad_nodes = []
    if self.dynamic_fields.intersection(self.op.output_fields):
      live_data = {}
      node_data = rpc.call_all_instances_info(nodes)
      for name in nodes:
        result = node_data[name]
        if result:
          live_data.update(result)
        elif result == False:
          bad_nodes.append(name)
        # else no instance is alive
    else:
      live_data = dict([(name, {}) for name in instance_names])

    # end data gathering

    output = []
    for instance in instance_list:
      iout = []
      for field in self.op.output_fields:
        if field == "name":
          val = instance.name
        elif field == "os":
          val = instance.os
        elif field == "pnode":
          val = instance.primary_node
        elif field == "snodes":
          val = list(instance.secondary_nodes)
        elif field == "admin_state":
          val = (instance.status != "down")
        elif field == "oper_state":
          if instance.primary_node in bad_nodes:
            val = None
          else:
            val = bool(live_data.get(instance.name))
        elif field == "admin_ram":
          val = instance.memory
        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 == "disk_template":
          val = instance.disk_template
        elif field == "ip":
          val = instance.nics[0].ip
        elif field == "bridge":
          val = instance.nics[0].bridge
        elif field == "mac":
          val = instance.nics[0].mac
        elif field == "sda_size" or field == "sdb_size":
          disk = instance.FindDisk(field[:3])
          if disk is None:
            val = None
          else:
            val = disk.size
        else:
          raise errors.ParameterError(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"]

  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.instance))
    nl = [self.sstore.GetMasterNode()] + list(self.instance.secondary_nodes)
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)

    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 "
                                   "DT_REMOTE_RAID1 template")

    # check memory requirements on the secondary node
    target_node = secondary_nodes[0]
    nodeinfo = rpc.call_node_info([target_node], self.cfg.GetVGName())
    info = nodeinfo.get(target_node, None)
    if not info:
      raise errors.OpPrereqError("Cannot get current information"
                                 " from node '%s'" % nodeinfo)
    if instance.memory > info['memory_free']:
      raise errors.OpPrereqError("Not enough memory on target node %s."
                                 " %d MB available, %d MB required" %
                                 (target_node, info['memory_free'],
                                  instance.memory))

    # check bridge existance
    brlist = [nic.bridge for nic in instance.nics]
    if not rpc.call_bridges_exist(target_node, brlist):
      raise errors.OpPrereqError("One or more target bridges %s does not"
                                 " exist on destination node '%s'" %
                                 (brlist, target_node))

    self.instance = instance

  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 remote_raid1, these are md over drbd
      if not _CheckDiskConsistency(self.cfg, dev, target_node, False):
        if not self.op.ignore_consistency:
          raise errors.OpExecError("Disk %s is degraded on target node,"
                                   " aborting failover." % dev.iv_name)

    feedback_fn("* checking target node resource availability")
    nodeinfo = rpc.call_node_info([target_node], self.cfg.GetVGName())

    if not nodeinfo:
      raise errors.OpExecError("Could not contact target node %s." %
                               target_node)

    free_memory = int(nodeinfo[target_node]['memory_free'])
    memory = instance.memory
    if memory > free_memory:
      raise errors.OpExecError("Not enough memory to create instance %s on"
                               " node %s. needed %s MiB, available %s MiB" %
                               (instance.name, target_node, memory,
                                free_memory))

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

    if not rpc.call_instance_shutdown(source_node, instance):
      if self.op.ignore_consistency:
        logger.Error("Could not shutdown instance %s on node %s. Proceeding"
                     " anyway. Please make sure node %s is down"  %
                     (instance.name, source_node, source_node))
      else:
        raise errors.OpExecError("Could not shutdown instance %s on node %s" %
                                 (instance.name, source_node))

    feedback_fn("* deactivating the instance's disks on source node")
    if not _ShutdownInstanceDisks(instance, self.cfg, 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.AddInstance(instance)

    feedback_fn("* activating the instance's disks on target node")
    logger.Info("Starting instance %s on node %s" %
                (instance.name, target_node))

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

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


def _CreateBlockDevOnPrimary(cfg, node, instance, device, info):
  """Create a tree of block devices on the primary node.

  This always creates all devices.

  """
  if device.children:
    for child in device.children:
      if not _CreateBlockDevOnPrimary(cfg, node, instance, child, info):
        return False

  cfg.SetDiskID(device, node)
  new_id = rpc.call_blockdev_create(node, device, device.size,
                                    instance.name, True, info)
  if not new_id:
    return False
  if device.physical_id is None:
    device.physical_id = new_id
  return True


def _CreateBlockDevOnSecondary(cfg, node, instance, device, force, info):
  """Create a tree of block devices on a secondary 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.

  """
  if device.CreateOnSecondary():
    force = True
  if device.children:
    for child in device.children:
      if not _CreateBlockDevOnSecondary(cfg, node, instance,
                                        child, force, info):
        return False

  if not force:
    return True
  cfg.SetDiskID(device, node)
  new_id = rpc.call_blockdev_create(node, device, device.size,
                                    instance.name, False, info)
  if not new_id:
    return False
  if device.physical_id is None:
    device.physical_id = new_id
  return True


def _GenerateUniqueNames(cfg, exts):
  """Generate a suitable LV name.

  This will generate a logical volume name for the given instance.

  """
  results = []
  for val in exts:
    new_id = cfg.GenerateUniqueID()
    results.append("%s%s" % (new_id, val))
  return results


def _GenerateMDDRBDBranch(cfg, primary, secondary, size, names):
  """Generate a drbd device complete with its children.

  """
  port = cfg.AllocatePort()
  vgname = cfg.GetVGName()
  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_DRBD7, size=size,
                          logical_id = (primary, secondary, port),
                          children = [dev_data, dev_meta])
  return drbd_dev


def _GenerateDRBD8Branch(cfg, primary, secondary, size, names, iv_name):
  """Generate a drbd8 device complete with its children.

  """
  port = cfg.AllocatePort()
  vgname = cfg.GetVGName()
  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),
                          children = [dev_data, dev_meta],
                          iv_name=iv_name)
  return drbd_dev

def _GenerateDiskTemplate(cfg, template_name,
                          instance_name, primary_node,
                          secondary_nodes, disk_sz, swap_sz):
  """Generate the entire disk layout for a given template type.

  """
  #TODO: compute space requirements

  vgname = cfg.GetVGName()
  if template_name == "diskless":
    disks = []
  elif template_name == "plain":
    if len(secondary_nodes) != 0:
      raise errors.ProgrammerError("Wrong template configuration")

    names = _GenerateUniqueNames(cfg, [".sda", ".sdb"])
    sda_dev = objects.Disk(dev_type=constants.LD_LV, size=disk_sz,
                           logical_id=(vgname, names[0]),
                           iv_name = "sda")
    sdb_dev = objects.Disk(dev_type=constants.LD_LV, size=swap_sz,
                           logical_id=(vgname, names[1]),
                           iv_name = "sdb")
    disks = [sda_dev, sdb_dev]
  elif template_name == "local_raid1":
    if len(secondary_nodes) != 0:
      raise errors.ProgrammerError("Wrong template configuration")


    names = _GenerateUniqueNames(cfg, [".sda_m1", ".sda_m2",
                                       ".sdb_m1", ".sdb_m2"])
    sda_dev_m1 = objects.Disk(dev_type=constants.LD_LV, size=disk_sz,
                              logical_id=(vgname, names[0]))
    sda_dev_m2 = objects.Disk(dev_type=constants.LD_LV, size=disk_sz,
                              logical_id=(vgname, names[1]))
    md_sda_dev = objects.Disk(dev_type=constants.LD_MD_R1, iv_name = "sda",
                              size=disk_sz,
                              children = [sda_dev_m1, sda_dev_m2])
    sdb_dev_m1 = objects.Disk(dev_type=constants.LD_LV, size=swap_sz,
                              logical_id=(vgname, names[2]))
    sdb_dev_m2 = objects.Disk(dev_type=constants.LD_LV, size=swap_sz,
                              logical_id=(vgname, names[3]))
    md_sdb_dev = objects.Disk(dev_type=constants.LD_MD_R1, iv_name = "sdb",
                              size=swap_sz,
                              children = [sdb_dev_m1, sdb_dev_m2])
    disks = [md_sda_dev, md_sdb_dev]
  elif template_name == constants.DT_REMOTE_RAID1:
    if len(secondary_nodes) != 1:
      raise errors.ProgrammerError("Wrong template configuration")
    remote_node = secondary_nodes[0]
    names = _GenerateUniqueNames(cfg, [".sda_data", ".sda_meta",
                                       ".sdb_data", ".sdb_meta"])
    drbd_sda_dev = _GenerateMDDRBDBranch(cfg, primary_node, remote_node,
                                         disk_sz, names[0:2])
    md_sda_dev = objects.Disk(dev_type=constants.LD_MD_R1, iv_name="sda",
                              children = [drbd_sda_dev], size=disk_sz)
    drbd_sdb_dev = _GenerateMDDRBDBranch(cfg, primary_node, remote_node,
                                         swap_sz, names[2:4])
    md_sdb_dev = objects.Disk(dev_type=constants.LD_MD_R1, iv_name="sdb",
                              children = [drbd_sdb_dev], size=swap_sz)
    disks = [md_sda_dev, md_sdb_dev]
  elif template_name == constants.DT_DRBD8:
    if len(secondary_nodes) != 1:
      raise errors.ProgrammerError("Wrong template configuration")
    remote_node = secondary_nodes[0]
    names = _GenerateUniqueNames(cfg, [".sda_data", ".sda_meta",
                                       ".sdb_data", ".sdb_meta"])
    drbd_sda_dev = _GenerateDRBD8Branch(cfg, primary_node, remote_node,
                                         disk_sz, names[0:2], "sda")
    drbd_sdb_dev = _GenerateDRBD8Branch(cfg, primary_node, remote_node,
                                         swap_sz, names[2:4], "sdb")
    disks = [drbd_sda_dev, drbd_sdb_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(cfg, instance):
  """Create all disks for an instance.

  This abstracts away some work from AddInstance.

  Args:
    instance: the instance object

  Returns:
    True or False showing the success of the creation process

  """
  info = _GetInstanceInfoText(instance)

  for device in instance.disks:
    logger.Info("creating volume %s for instance %s" %
              (device.iv_name, instance.name))
    #HARDCODE
    for secondary_node in instance.secondary_nodes:
      if not _CreateBlockDevOnSecondary(cfg, secondary_node, instance,
                                        device, False, info):
        logger.Error("failed to create volume %s (%s) on secondary node %s!" %
                     (device.iv_name, device, secondary_node))
        return False
    #HARDCODE
    if not _CreateBlockDevOnPrimary(cfg, instance.primary_node,
                                    instance, device, info):
      logger.Error("failed to create volume %s on primary!" %
                   device.iv_name)
      return False
  return True


def _RemoveDisks(instance, cfg):
  """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()`).

  Args:
    instance: the instance object

  Returns:
    True or False showing the success of the removal proces

  """
  logger.Info("removing block devices for instance %s" % instance.name)

  result = True
  for device in instance.disks:
    for node, disk in device.ComputeNodeTree(instance.primary_node):
      cfg.SetDiskID(disk, node)
      if not rpc.call_blockdev_remove(node, disk):
        logger.Error("could not remove block device %s on node %s,"
                     " continuing anyway" %
                     (device.iv_name, node))
        result = False
  return result


class LUCreateInstance(LogicalUnit):
  """Create an instance.

  """
  HPATH = "instance-add"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "mem_size", "disk_size", "pnode",
              "disk_template", "swap_size", "mode", "start", "vcpus",
              "wait_for_sync", "ip_check", "mac"]

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

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

    """
    env = {
      "INSTANCE_DISK_TEMPLATE": self.op.disk_template,
      "INSTANCE_DISK_SIZE": self.op.disk_size,
      "INSTANCE_SWAP_SIZE": self.op.swap_size,
      "INSTANCE_ADD_MODE": self.op.mode,
      }
    if self.op.mode == constants.INSTANCE_IMPORT:
      env["INSTANCE_SRC_NODE"] = self.op.src_node
      env["INSTANCE_SRC_PATH"] = self.op.src_path
      env["INSTANCE_SRC_IMAGE"] = self.src_image

    env.update(_BuildInstanceHookEnv(name=self.op.instance_name,
      primary_node=self.op.pnode,
      secondary_nodes=self.secondaries,
      status=self.instance_status,
      os_type=self.op.os_type,
      memory=self.op.mem_size,
      vcpus=self.op.vcpus,
      nics=[(self.inst_ip, self.op.bridge)],
    ))

    nl = ([self.sstore.GetMasterNode(), self.op.pnode] +
          self.secondaries)
    return env, nl, nl


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

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

    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_node is None or src_path is None:
        raise errors.OpPrereqError("Importing an instance requires source"
                                   " node and path options")
      src_node_full = self.cfg.ExpandNodeName(src_node)
      if src_node_full is None:
        raise errors.OpPrereqError("Unknown source node '%s'" % src_node)
      self.op.src_node = src_node = src_node_full

      if not os.path.isabs(src_path):
        raise errors.OpPrereqError("The source path must be absolute")

      export_info = rpc.call_export_info(src_node, src_path)

      if not export_info:
        raise errors.OpPrereqError("No export found in dir %s" % src_path)

      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))

      if int(export_info.get(constants.INISECT_INS, 'disk_count')) > 1:
        raise errors.OpPrereqError("Can't import instance with more than"
                                   " one data disk")

      # FIXME: are the old os-es, disk sizes, etc. useful?
      self.op.os_type = export_info.get(constants.INISECT_EXP, 'os')
      diskimage = os.path.join(src_path, export_info.get(constants.INISECT_INS,
                                                         'disk0_dump'))
      self.src_image = diskimage
    else: # INSTANCE_CREATE
      if getattr(self.op, "os_type", None) is None:
        raise errors.OpPrereqError("No guest OS specified")

    # check primary node
    pnode = self.cfg.GetNodeInfo(self.cfg.ExpandNodeName(self.op.pnode))
    if pnode is None:
      raise errors.OpPrereqError("Primary node '%s' is unknown" %
                                 self.op.pnode)
    self.op.pnode = pnode.name
    self.pnode = pnode
    self.secondaries = []
    # 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.disk_template in constants.DTS_NET_MIRROR:
      if getattr(self.op, "snode", None) is None:
        raise errors.OpPrereqError("The networked disk templates need"
                                   " a mirror node")

      snode_name = self.cfg.ExpandNodeName(self.op.snode)
      if snode_name is None:
        raise errors.OpPrereqError("Unknown secondary node '%s'" %
                                   self.op.snode)
      elif snode_name == pnode.name:
        raise errors.OpPrereqError("The secondary node cannot be"
                                   " the primary node.")
      self.secondaries.append(snode_name)

    # Check lv size requirements
    nodenames = [pnode.name] + self.secondaries
    nodeinfo = rpc.call_node_info(nodenames, self.cfg.GetVGName())

    # Required free disk space as a function of disk and swap space
    req_size_dict = {
      constants.DT_DISKLESS: 0,
      constants.DT_PLAIN: self.op.disk_size + self.op.swap_size,
      constants.DT_LOCAL_RAID1: (self.op.disk_size + self.op.swap_size) * 2,
      # 256 MB are added for drbd metadata, 128MB for each drbd device
      constants.DT_REMOTE_RAID1: self.op.disk_size + self.op.swap_size + 256,
      constants.DT_DRBD8: self.op.disk_size + self.op.swap_size + 256,
    }

    if self.op.disk_template not in req_size_dict:
      raise errors.ProgrammerError("Disk template '%s' size requirement"
                                   " is unknown" %  self.op.disk_template)

    req_size = req_size_dict[self.op.disk_template]

    for node in nodenames:
      info = nodeinfo.get(node, None)
      if not info:
        raise errors.OpPrereqError("Cannot get current information"
                                   " from node '%s'" % nodeinfo)
      if req_size > info['vg_free']:
        raise errors.OpPrereqError("Not enough disk space on target node %s."
                                   " %d MB available, %d MB required" %
                                   (node, info['vg_free'], req_size))

    # os verification
    os_obj = rpc.call_os_get(pnode.name, self.op.os_type)
    if not os_obj:
      raise errors.OpPrereqError("OS '%s' not in supported os list for"
                                 " primary node"  % self.op.os_type)

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

    self.op.instance_name = instance_name = hostname1.name
    instance_list = self.cfg.GetInstanceList()
    if instance_name in instance_list:
      raise errors.OpPrereqError("Instance '%s' is already in the cluster" %
                                 instance_name)

    ip = getattr(self.op, "ip", None)
    if ip is None or ip.lower() == "none":
      inst_ip = None
    elif ip.lower() == "auto":
      inst_ip = hostname1.ip
    else:
      if not utils.IsValidIP(ip):
        raise errors.OpPrereqError("given IP address '%s' doesn't look"
                                   " like a valid IP" % ip)
      inst_ip = ip
    self.inst_ip = inst_ip

    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(utils.HostInfo().name, hostname1.ip,
                       constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("IP %s of instance %s already in use" %
                                   (hostname1.ip, instance_name))

    # MAC address verification
    if self.op.mac != "auto":
      if not utils.IsValidMac(self.op.mac.lower()):
        raise errors.OpPrereqError("invalid MAC address specified: %s" %
                                   self.op.mac)

    # bridge verification
    bridge = getattr(self.op, "bridge", None)
    if bridge is None:
      self.op.bridge = self.cfg.GetDefBridge()
    else:
      self.op.bridge = bridge

    if not rpc.call_bridges_exist(self.pnode.name, [self.op.bridge]):
      raise errors.OpPrereqError("target bridge '%s' does not exist on"
                                 " destination node '%s'" %
                                 (self.op.bridge, pnode.name))

    if self.op.start:
      self.instance_status = 'up'
    else:
      self.instance_status = 'down'

  def Exec(self, feedback_fn):
    """Create and add the instance to the cluster.

    """
    instance = self.op.instance_name
    pnode_name = self.pnode.name

    if self.op.mac == "auto":
      mac_address=self.cfg.GenerateMAC()
    else:
      mac_address=self.op.mac

    nic = objects.NIC(bridge=self.op.bridge, mac=mac_address)
    if self.inst_ip is not None:
      nic.ip = self.inst_ip

    ht_kind = self.sstore.GetHypervisorType()
    if ht_kind in constants.HTS_REQ_PORT:
      network_port = self.cfg.AllocatePort()
    else:
      network_port = None

    disks = _GenerateDiskTemplate(self.cfg,
                                  self.op.disk_template,
                                  instance, pnode_name,
                                  self.secondaries, self.op.disk_size,
                                  self.op.swap_size)

    iobj = objects.Instance(name=instance, os=self.op.os_type,
                            primary_node=pnode_name,
                            memory=self.op.mem_size,
                            vcpus=self.op.vcpus,
                            nics=[nic], disks=disks,
                            disk_template=self.op.disk_template,
                            status=self.instance_status,
                            network_port=network_port,
                            )

    feedback_fn("* creating instance disks...")
    if not _CreateDisks(self.cfg, iobj):
      _RemoveDisks(iobj, self.cfg)
      raise errors.OpExecError("Device creation failed, reverting...")

    feedback_fn("adding instance %s to cluster config" % instance)

    self.cfg.AddInstance(iobj)

    if self.op.wait_for_sync:
      disk_abort = not _WaitForSync(self.cfg, iobj, self.proc)
    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.cfg, iobj, self.proc, oneshot=True)
    else:
      disk_abort = False

    if disk_abort:
      _RemoveDisks(iobj, self.cfg)
      self.cfg.RemoveInstance(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...")
        if not rpc.call_instance_os_add(pnode_name, iobj, "sda", "sdb"):
          raise errors.OpExecError("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_image = self.src_image
        if not rpc.call_instance_os_import(pnode_name, iobj, "sda", "sdb",
                                                src_node, src_image):
          raise errors.OpExecError("Could not import os for instance"
                                   " %s on node %s" %
                                   (instance, pnode_name))
      else:
        # also checked in the prereq part
        raise errors.ProgrammerError("Unknown OS initialization mode '%s'"
                                     % self.op.mode)

    if self.op.start:
      logger.Info("starting instance %s on node %s" % (instance, pnode_name))
      feedback_fn("* starting instance...")
      if not rpc.call_instance_start(pnode_name, iobj, None):
        raise errors.OpExecError("Could not start instance")


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"]

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

  def Exec(self, feedback_fn):
    """Connect to the console of an instance

    """
    instance = self.instance
    node = instance.primary_node

    node_insts = rpc.call_instance_list([node])[node]
    if node_insts is False:
      raise errors.OpExecError("Can't connect to node %s." % node)

    if instance.name not in node_insts:
      raise errors.OpExecError("Instance %s is not running." % instance.name)

    logger.Debug("connecting to console of %s on %s" % (instance.name, node))

    hyper = hypervisor.GetHypervisor()
    console_cmd = hyper.GetShellCommandForConsole(instance)
    # build ssh cmdline
    argv = ["ssh", "-q", "-t"]
    argv.extend(ssh.KNOWN_HOSTS_OPTS)
    argv.extend(ssh.BATCH_MODE_OPTS)
    argv.append(node)
    argv.append(console_cmd)
    return "ssh", argv


class LUAddMDDRBDComponent(LogicalUnit):
  """Adda new mirror member to an instance's disk.

  """
  HPATH = "mirror-add"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "remote_node", "disk_name"]

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

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "NEW_SECONDARY": self.op.remote_node,
      "DISK_NAME": self.op.disk_name,
      }
    env.update(_BuildInstanceHookEnvByObject(self.instance))
    nl = [self.sstore.GetMasterNode(), self.instance.primary_node,
          self.op.remote_node,] + list(self.instance.secondary_nodes)
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

    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.remote_node = remote_node

    if remote_node == instance.primary_node:
      raise errors.OpPrereqError("The specified node is the primary node of"
                                 " the instance.")

    if instance.disk_template != constants.DT_REMOTE_RAID1:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " remote_raid1.")
    for disk in instance.disks:
      if disk.iv_name == self.op.disk_name:
        break
    else:
      raise errors.OpPrereqError("Can't find this device ('%s') in the"
                                 " instance." % self.op.disk_name)
    if len(disk.children) > 1:
      raise errors.OpPrereqError("The device already has two slave devices."
                                 " This would create a 3-disk raid1 which we"
                                 " don't allow.")
    self.disk = disk

  def Exec(self, feedback_fn):
    """Add the mirror component

    """
    disk = self.disk
    instance = self.instance

    remote_node = self.remote_node
    lv_names = [".%s_%s" % (disk.iv_name, suf) for suf in ["data", "meta"]]
    names = _GenerateUniqueNames(self.cfg, lv_names)
    new_drbd = _GenerateMDDRBDBranch(self.cfg, instance.primary_node,
                                     remote_node, disk.size, names)

    logger.Info("adding new mirror component on secondary")
    #HARDCODE
    if not _CreateBlockDevOnSecondary(self.cfg, remote_node, instance,
                                      new_drbd, False,
                                      _GetInstanceInfoText(instance)):
      raise errors.OpExecError("Failed to create new component on secondary"
                               " node %s" % remote_node)

    logger.Info("adding new mirror component on primary")
    #HARDCODE
    if not _CreateBlockDevOnPrimary(self.cfg, instance.primary_node,
                                    instance, new_drbd,
                                    _GetInstanceInfoText(instance)):
      # remove secondary dev
      self.cfg.SetDiskID(new_drbd, remote_node)
      rpc.call_blockdev_remove(remote_node, new_drbd)
      raise errors.OpExecError("Failed to create volume on primary")

    # the device exists now
    # call the primary node to add the mirror to md
    logger.Info("adding new mirror component to md")
    if not rpc.call_blockdev_addchildren(instance.primary_node,
                                         disk, [new_drbd]):
      logger.Error("Can't add mirror compoment to md!")
      self.cfg.SetDiskID(new_drbd, remote_node)
      if not rpc.call_blockdev_remove(remote_node, new_drbd):
        logger.Error("Can't rollback on secondary")
      self.cfg.SetDiskID(new_drbd, instance.primary_node)
      if not rpc.call_blockdev_remove(instance.primary_node, new_drbd):
        logger.Error("Can't rollback on primary")
      raise errors.OpExecError("Can't add mirror component to md array")

    disk.children.append(new_drbd)

    self.cfg.AddInstance(instance)

    _WaitForSync(self.cfg, instance, self.proc)

    return 0


class LURemoveMDDRBDComponent(LogicalUnit):
  """Remove a component from a remote_raid1 disk.

  """
  HPATH = "mirror-remove"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "disk_name", "disk_id"]

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

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "DISK_NAME": self.op.disk_name,
      "DISK_ID": self.op.disk_id,
      "OLD_SECONDARY": self.old_secondary,
      }
    env.update(_BuildInstanceHookEnvByObject(self.instance))
    nl = [self.sstore.GetMasterNode(),
          self.instance.primary_node] + list(self.instance.secondary_nodes)
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance

    if instance.disk_template != constants.DT_REMOTE_RAID1:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " remote_raid1.")
    for disk in instance.disks:
      if disk.iv_name == self.op.disk_name:
        break
    else:
      raise errors.OpPrereqError("Can't find this device ('%s') in the"
                                 " instance." % self.op.disk_name)
    for child in disk.children:
      if (child.dev_type == constants.LD_DRBD7 and
          child.logical_id[2] == self.op.disk_id):
        break
    else:
      raise errors.OpPrereqError("Can't find the device with this port.")

    if len(disk.children) < 2:
      raise errors.OpPrereqError("Cannot remove the last component from"
                                 " a mirror.")
    self.disk = disk
    self.child = child
    if self.child.logical_id[0] == instance.primary_node:
      oid = 1
    else:
      oid = 0
    self.old_secondary = self.child.logical_id[oid]

  def Exec(self, feedback_fn):
    """Remove the mirror component

    """
    instance = self.instance
    disk = self.disk
    child = self.child
    logger.Info("remove mirror component")
    self.cfg.SetDiskID(disk, instance.primary_node)
    if not rpc.call_blockdev_removechildren(instance.primary_node,
                                            disk, [child]):
      raise errors.OpExecError("Can't remove child from mirror.")

    for node in child.logical_id[:2]:
      self.cfg.SetDiskID(child, node)
      if not rpc.call_blockdev_remove(node, child):
        logger.Error("Warning: failed to remove device from node %s,"
                     " continuing operation." % node)

    disk.children.remove(child)
    self.cfg.AddInstance(instance)


class LUReplaceDisks(LogicalUnit):
  """Replace the disks of an instance.

  """
  HPATH = "mirrors-replace"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name", "mode", "disks"]

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

    This runs on the master, the primary and all the secondaries.

    """
    env = {
      "MODE": self.op.mode,
      "NEW_SECONDARY": self.op.remote_node,
      "OLD_SECONDARY": self.instance.secondary_nodes[0],
      }
    env.update(_BuildInstanceHookEnvByObject(self.instance))
    nl = [
      self.sstore.GetMasterNode(),
      self.instance.primary_node,
      ]
    if self.op.remote_node is not None:
      nl.append(self.op.remote_node)
    return env, nl, nl

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

    This checks that the instance is in the cluster.

    """
    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)
    self.instance = instance
    self.op.instance_name = instance.name

    if instance.disk_template not in constants.DTS_NET_MIRROR:
      raise errors.OpPrereqError("Instance's disk layout is not"
                                 " network mirrored.")

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

    self.sec_node = instance.secondary_nodes[0]

    remote_node = getattr(self.op, "remote_node", None)
    if remote_node is not None:
      remote_node = self.cfg.ExpandNodeName(remote_node)
      if remote_node is None:
        raise errors.OpPrereqError("Node '%s' not known" %
                                   self.op.remote_node)
      self.remote_node_info = self.cfg.GetNodeInfo(remote_node)
    else:
      self.remote_node_info = None
    if remote_node == instance.primary_node:
      raise errors.OpPrereqError("The specified node is the primary node of"
                                 " the instance.")
    elif remote_node == self.sec_node:
      if self.op.mode == constants.REPLACE_DISK_SEC:
        # this is for DRBD8, where we can't execute the same mode of
        # replacement as for drbd7 (no different port allocated)
        raise errors.OpPrereqError("Same secondary given, cannot execute"
                                   " replacement")
      # the user gave the current secondary, switch to
      # 'no-replace-secondary' mode for drbd7
      remote_node = None
    if (instance.disk_template == constants.DT_REMOTE_RAID1 and
        self.op.mode != constants.REPLACE_DISK_ALL):
      raise errors.OpPrereqError("Template 'remote_raid1' only allows all"
                                 " disks replacement, not individual ones")
    if instance.disk_template == constants.DT_DRBD8:
      if (self.op.mode == constants.REPLACE_DISK_ALL and
          remote_node is not None):
        # switch to replace secondary mode
        self.op.mode = constants.REPLACE_DISK_SEC

      if self.op.mode == constants.REPLACE_DISK_ALL:
        raise errors.OpPrereqError("Template 'drbd' only allows primary or"
                                   " secondary disk replacement, not"
                                   " both at once")
      elif self.op.mode == constants.REPLACE_DISK_PRI:
        if remote_node is not None:
          raise errors.OpPrereqError("Template 'drbd' does not allow changing"
                                     " the secondary while doing a primary"
                                     " node disk replacement")
        self.tgt_node = instance.primary_node
        self.oth_node = instance.secondary_nodes[0]
      elif self.op.mode == constants.REPLACE_DISK_SEC:
        self.new_node = remote_node # this can be None, in which case
                                    # we don't change the secondary
        self.tgt_node = instance.secondary_nodes[0]
        self.oth_node = instance.primary_node
      else:
        raise errors.ProgrammerError("Unhandled disk replace mode")

    for name in self.op.disks:
      if instance.FindDisk(name) is None:
        raise errors.OpPrereqError("Disk '%s' not found for instance '%s'" %
                                   (name, instance.name))
    self.op.remote_node = remote_node

  def _ExecRR1(self, feedback_fn):
    """Replace the disks of an instance.

    """
    instance = self.instance
    iv_names = {}
    # start of work
    if self.op.remote_node is None:
      remote_node = self.sec_node
    else:
      remote_node = self.op.remote_node
    cfg = self.cfg
    for dev in instance.disks:
      size = dev.size
      lv_names = [".%s_%s" % (dev.iv_name, suf) for suf in ["data", "meta"]]
      names = _GenerateUniqueNames(cfg, lv_names)
      new_drbd = _GenerateMDDRBDBranch(cfg, instance.primary_node,
                                       remote_node, size, names)
      iv_names[dev.iv_name] = (dev, dev.children[0], new_drbd)
      logger.Info("adding new mirror component on secondary for %s" %
                  dev.iv_name)
      #HARDCODE
      if not _CreateBlockDevOnSecondary(cfg, remote_node, instance,
                                        new_drbd, False,
                                        _GetInstanceInfoText(instance)):
        raise errors.OpExecError("Failed to create new component on secondary"
                                 " node %s. Full abort, cleanup manually!" %
                                 remote_node)

      logger.Info("adding new mirror component on primary")
      #HARDCODE
      if not _CreateBlockDevOnPrimary(cfg, instance.primary_node,
                                      instance, new_drbd,
                                      _GetInstanceInfoText(instance)):
        # remove secondary dev
        cfg.SetDiskID(new_drbd, remote_node)
        rpc.call_blockdev_remove(remote_node, new_drbd)
        raise errors.OpExecError("Failed to create volume on primary!"
                                 " Full abort, cleanup manually!!")

      # the device exists now
      # call the primary node to add the mirror to md
      logger.Info("adding new mirror component to md")
      if not rpc.call_blockdev_addchildren(instance.primary_node, dev,
                                           [new_drbd]):
        logger.Error("Can't add mirror compoment to md!")
        cfg.SetDiskID(new_drbd, remote_node)
        if not rpc.call_blockdev_remove(remote_node, new_drbd):
          logger.Error("Can't rollback on secondary")
        cfg.SetDiskID(new_drbd, instance.primary_node)
        if not rpc.call_blockdev_remove(instance.primary_node, new_drbd):
          logger.Error("Can't rollback on primary")
        raise errors.OpExecError("Full abort, cleanup manually!!")

      dev.children.append(new_drbd)
      cfg.AddInstance(instance)

    # 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
    _WaitForSync(cfg, instance, self.proc, unlock=True)

    # so check manually all the devices
    for name in iv_names:
      dev, child, new_drbd = iv_names[name]
      cfg.SetDiskID(dev, instance.primary_node)
      is_degr = rpc.call_blockdev_find(instance.primary_node, dev)[5]
      if is_degr:
        raise errors.OpExecError("MD device %s is degraded!" % name)
      cfg.SetDiskID(new_drbd, instance.primary_node)
      is_degr = rpc.call_blockdev_find(instance.primary_node, new_drbd)[5]
      if is_degr:
        raise errors.OpExecError("New drbd device %s is degraded!" % name)

    for name in iv_names:
      dev, child, new_drbd = iv_names[name]
      logger.Info("remove mirror %s component" % name)
      cfg.SetDiskID(dev, instance.primary_node)
      if not rpc.call_blockdev_removechildren(instance.primary_node,
                                              dev, [child]):
        logger.Error("Can't remove child from mirror, aborting"
                     " *this device cleanup*.\nYou need to cleanup manually!!")
        continue

      for node in child.logical_id[:2]:
        logger.Info("remove child device on %s" % node)
        cfg.SetDiskID(child, node)
        if not rpc.call_blockdev_remove(node, child):
          logger.Error("Warning: failed to remove device from node %s,"
                       " continuing operation." % node)

      dev.children.remove(child)

      cfg.AddInstance(instance)

  def _ExecD8DiskOnly(self, feedback_fn):
    """Replace a disk on the primary or secondary for dbrd8.

    The algorithm for replace is quite complicated:
      - for each disk to be replaced:
        - create new LVs on the target node with unique names
        - detach old LVs from the drbd device
        - rename old LVs to name_replaced.<time_t>
        - rename new LVs to old LVs
        - attach the new LVs (with the old names now) to the drbd device
      - wait for sync across all devices
      - for each modified disk:
        - remove old LVs (which have the name name_replaces.<time_t>)

    Failures are not very well handled.

    """
    steps_total = 6
    warning, info = (self.proc.LogWarning, self.proc.LogInfo)
    instance = self.instance
    iv_names = {}
    vgname = self.cfg.GetVGName()
    # start of work
    cfg = self.cfg
    tgt_node = self.tgt_node
    oth_node = self.oth_node

    # Step: check device activation
    self.proc.LogStep(1, steps_total, "check device existence")
    info("checking volume groups")
    my_vg = cfg.GetVGName()
    results = rpc.call_vg_list([oth_node, tgt_node])
    if not results:
      raise errors.OpExecError("Can't list volume groups on the nodes")
    for node in oth_node, tgt_node:
      res = results.get(node, False)
      if not res or my_vg not in res:
        raise errors.OpExecError("Volume group '%s' not found on %s" %
                                 (my_vg, node))
    for dev in instance.disks:
      if not dev.iv_name in self.op.disks:
        continue
      for node in tgt_node, oth_node:
        info("checking %s on %s" % (dev.iv_name, node))
        cfg.SetDiskID(dev, node)
        if not rpc.call_blockdev_find(node, dev):
          raise errors.OpExecError("Can't find device %s on node %s" %
                                   (dev.iv_name, node))

    # Step: check other node consistency
    self.proc.LogStep(2, steps_total, "check peer consistency")
    for dev in instance.disks:
      if not dev.iv_name in self.op.disks:
        continue
      info("checking %s consistency on %s" % (dev.iv_name, oth_node))
      if not _CheckDiskConsistency(self.cfg, dev, oth_node,
                                   oth_node==instance.primary_node):
        raise errors.OpExecError("Peer node (%s) has degraded storage, unsafe"
                                 " to replace disks on this node (%s)" %
                                 (oth_node, tgt_node))

    # Step: create new storage
    self.proc.LogStep(3, steps_total, "allocate new storage")
    for dev in instance.disks:
      if not dev.iv_name in self.op.disks:
        continue
      size = dev.size
      cfg.SetDiskID(dev, tgt_node)
      lv_names = [".%s_%s" % (dev.iv_name, suf) for suf in ["data", "meta"]]
      names = _GenerateUniqueNames(cfg, lv_names)
      lv_data = objects.Disk(dev_type=constants.LD_LV, size=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)
      info("creating new local storage on %s for %s" %
           (tgt_node, dev.iv_name))
      # since we *always* want to create this LV, we use the
      # _Create...OnPrimary (which forces the creation), even if we
      # are talking about the secondary node
      for new_lv in new_lvs:
        if not _CreateBlockDevOnPrimary(cfg, tgt_node, instance, new_lv,
                                        _GetInstanceInfoText(instance)):
          raise errors.OpExecError("Failed to create new LV named '%s' on"
                                   " node '%s'" %
                                   (new_lv.logical_id[1], tgt_node))

    # Step: for each lv, detach+rename*2+attach
    self.proc.LogStep(4, steps_total, "change drbd configuration")
    for dev, old_lvs, new_lvs in iv_names.itervalues():
      info("detaching %s drbd from local storage" % dev.iv_name)
      if not rpc.call_blockdev_removechildren(tgt_node, dev, old_lvs):
        raise errors.OpExecError("Can't detach drbd from local storage on node"
                                 " %s for device %s" % (tgt_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 than 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
      rlist = []
      for to_ren in old_lvs:
        find_res = rpc.call_blockdev_find(tgt_node, to_ren)
        if find_res is not None: # device exists
          rlist.append((to_ren, ren_fn(to_ren, temp_suffix)))

      info("renaming the old LVs on the target node")
      if not rpc.call_blockdev_rename(tgt_node, rlist):
        raise errors.OpExecError("Can't rename old LVs on node %s" % tgt_node)
      # now we rename the new LVs to the old LVs
      info("renaming the new LVs on the target node")
      rlist = [(new, old.physical_id) for old, new in zip(old_lvs, new_lvs)]
      if not rpc.call_blockdev_rename(tgt_node, rlist):
        raise errors.OpExecError("Can't rename new LVs on node %s" % tgt_node)

      for old, new in zip(old_lvs, new_lvs):
        new.logical_id = old.logical_id
        cfg.SetDiskID(new, tgt_node)

      for disk in old_lvs:
        disk.logical_id = ren_fn(disk, temp_suffix)
        cfg.SetDiskID(disk, tgt_node)

      # now that the new lvs have the old name, we can add them to the device
      info("adding new mirror component on %s" % tgt_node)
      if not rpc.call_blockdev_addchildren(tgt_node, dev, new_lvs):
        for new_lv in new_lvs:
          if not rpc.call_blockdev_remove(tgt_node, new_lv):
            warning("Can't rollback device %s", hint="manually cleanup unused"
                    " logical volumes")
        raise errors.OpExecError("Can't add local storage to drbd")

      dev.children = new_lvs
      cfg.Update(instance)

    # Step: 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.proc.LogStep(5, steps_total, "sync devices")
    _WaitForSync(cfg, instance, self.proc, unlock=True)

    # so check manually all the devices
    for name, (dev, old_lvs, new_lvs) in iv_names.iteritems():
      cfg.SetDiskID(dev, instance.primary_node)
      is_degr = rpc.call_blockdev_find(instance.primary_node, dev)[5]
      if is_degr:
        raise errors.OpExecError("DRBD device %s is degraded!" % name)

    # Step: remove old storage
    self.proc.LogStep(6, steps_total, "removing old storage")
    for name, (dev, old_lvs, new_lvs) in iv_names.iteritems():
      info("remove logical volumes for %s" % name)
      for lv in old_lvs:
        cfg.SetDiskID(lv, tgt_node)
        if not rpc.call_blockdev_remove(tgt_node, lv):
          warning("Can't remove old LV", hint="manually remove unused LVs")
          continue

  def _ExecD8Secondary(self, feedback_fn):
    """Replace the secondary node for drbd8.

    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
    warning, info = (self.proc.LogWarning, self.proc.LogInfo)
    instance = self.instance
    iv_names = {}
    vgname = self.cfg.GetVGName()
    # start of work
    cfg = self.cfg
    old_node = self.tgt_node
    new_node = self.new_node
    pri_node = instance.primary_node

    # Step: check device activation
    self.proc.LogStep(1, steps_total, "check device existence")
    info("checking volume groups")
    my_vg = cfg.GetVGName()
    results = rpc.call_vg_list([pri_node, new_node])
    if not results:
      raise errors.OpExecError("Can't list volume groups on the nodes")
    for node in pri_node, new_node:
      res = results.get(node, False)
      if not res or my_vg not in res:
        raise errors.OpExecError("Volume group '%s' not found on %s" %
                                 (my_vg, node))
    for dev in instance.disks:
      if not dev.iv_name in self.op.disks:
        continue
      info("checking %s on %s" % (dev.iv_name, pri_node))
      cfg.SetDiskID(dev, pri_node)
      if not rpc.call_blockdev_find(pri_node, dev):
        raise errors.OpExecError("Can't find device %s on node %s" %
                                 (dev.iv_name, pri_node))

    # Step: check other node consistency
    self.proc.LogStep(2, steps_total, "check peer consistency")
    for dev in instance.disks:
      if not dev.iv_name in self.op.disks:
        continue
      info("checking %s consistency on %s" % (dev.iv_name, pri_node))
      if not _CheckDiskConsistency(self.cfg, dev, pri_node, True, ldisk=True):
        raise errors.OpExecError("Primary node (%s) has degraded storage,"
                                 " unsafe to replace the secondary" %
                                 pri_node)

    # Step: create new storage
    self.proc.LogStep(3, steps_total, "allocate new storage")
    for dev in instance.disks:
      size = dev.size
      info("adding new local storage on %s for %s" % (new_node, dev.iv_name))
      # since we *always* want to create this LV, we use the
      # _Create...OnPrimary (which forces the creation), even if we
      # are talking about the secondary node
      for new_lv in dev.children:
        if not _CreateBlockDevOnPrimary(cfg, new_node, instance, new_lv,
                                        _GetInstanceInfoText(instance)):
          raise errors.OpExecError("Failed to create new LV named '%s' on"
                                   " node '%s'" %
                                   (new_lv.logical_id[1], new_node))

      iv_names[dev.iv_name] = (dev, dev.children)

    self.proc.LogStep(4, steps_total, "changing drbd configuration")
    for dev in instance.disks:
      size = dev.size
      info("activating a new drbd on %s for %s" % (new_node, dev.iv_name))
      # create new devices on new_node
      new_drbd = objects.Disk(dev_type=constants.LD_DRBD8,
                              logical_id=(pri_node, new_node,
                                          dev.logical_id[2]),
                              children=dev.children)
      if not _CreateBlockDevOnSecondary(cfg, new_node, instance,
                                        new_drbd, False,
                                      _GetInstanceInfoText(instance)):
        raise errors.OpExecError("Failed to create new DRBD on"
                                 " node '%s'" % new_node)

    for dev in instance.disks:
      # we have new devices, shutdown the drbd on the old secondary
      info("shutting down drbd for %s on old node" % dev.iv_name)
      cfg.SetDiskID(dev, old_node)
      if not rpc.call_blockdev_shutdown(old_node, dev):
        warning("Failed to shutdown drbd for %s on old node" % dev.iv_name,
                hint="Please cleanup this device manually as soon as possible")

    info("detaching primary drbds from the network (=> standalone)")
    done = 0
    for dev in instance.disks:
      cfg.SetDiskID(dev, pri_node)
      # set the physical (unique in bdev terms) id to None, meaning
      # detach from network
      dev.physical_id = (None,) * len(dev.physical_id)
      # and 'find' the device, which will 'fix' it to match the
      # standalone state
      if rpc.call_blockdev_find(pri_node, dev):
        done += 1
      else:
        warning("Failed to detach drbd %s from network, unusual case" %
                dev.iv_name)

    if not done:
      # no detaches succeeded (very unlikely)
      raise errors.OpExecError("Can't detach at least one DRBD from old node")

    # if we managed to detach at least one, we update all the disks of
    # the instance to point to the new secondary
    info("updating instance configuration")
    for dev in instance.disks:
      dev.logical_id = (pri_node, new_node) + dev.logical_id[2:]
      cfg.SetDiskID(dev, pri_node)
    cfg.Update(instance)

    # and now perform the drbd attach
    info("attaching primary drbds to new secondary (standalone => connected)")
    failures = []
    for dev in instance.disks:
      info("attaching primary drbd for %s to new secondary node" % dev.iv_name)
      # since the attach is smart, it's enough to 'find' the device,
      # it will automatically activate the network, if the physical_id
      # is correct
      cfg.SetDiskID(dev, pri_node)
      if not rpc.call_blockdev_find(pri_node, dev):
        warning("can't attach drbd %s to new secondary!" % dev.iv_name,
                "please do a gnt-instance info to see the status of disks")

    # 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.proc.LogStep(5, steps_total, "sync devices")
    _WaitForSync(cfg, instance, self.proc, unlock=True)

    # so check manually all the devices
    for name, (dev, old_lvs) in iv_names.iteritems():
      cfg.SetDiskID(dev, pri_node)
      is_degr = rpc.call_blockdev_find(pri_node, dev)[5]
      if is_degr:
        raise errors.OpExecError("DRBD device %s is degraded!" % name)

    self.proc.LogStep(6, steps_total, "removing old storage")
    for name, (dev, old_lvs) in iv_names.iteritems():
      info("remove logical volumes for %s" % name)
      for lv in old_lvs:
        cfg.SetDiskID(lv, old_node)
        if not rpc.call_blockdev_remove(old_node, lv):
          warning("Can't remove LV on old secondary",
                  hint="Cleanup stale volumes by hand")

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

    This dispatches the disk replacement to the appropriate handler.

    """
    instance = self.instance
    if instance.disk_template == constants.DT_REMOTE_RAID1:
      fn = self._ExecRR1
    elif instance.disk_template == constants.DT_DRBD8:
      if self.op.remote_node is None:
        fn = self._ExecD8DiskOnly
      else:
        fn = self._ExecD8Secondary
    else:
      raise errors.ProgrammerError("Unhandled disk replacement case")
    return fn(feedback_fn)


class LUQueryInstanceData(NoHooksLU):
  """Query runtime instance data.

  """
  _OP_REQP = ["instances"]

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

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

    """
    if not isinstance(self.op.instances, list):
      raise errors.OpPrereqError("Invalid argument type 'instances'")
    if self.op.instances:
      self.wanted_instances = []
      names = self.op.instances
      for name in names:
        instance = self.cfg.GetInstanceInfo(self.cfg.ExpandInstanceName(name))
        if instance is None:
          raise errors.OpPrereqError("No such instance name '%s'" % name)
      self.wanted_instances.append(instance)
    else:
      self.wanted_instances = [self.cfg.GetInstanceInfo(name) for name
                               in self.cfg.GetInstanceList()]
    return


  def _ComputeDiskStatus(self, instance, snode, dev):
    """Compute block device status.

    """
    self.cfg.SetDiskID(dev, instance.primary_node)
    dev_pstatus = rpc.call_blockdev_find(instance.primary_node, dev)
    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]

    if snode:
      self.cfg.SetDiskID(dev, snode)
      dev_sstatus = rpc.call_blockdev_find(snode, dev)
    else:
      dev_sstatus = None

    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,
      }

    return data

  def Exec(self, feedback_fn):
    """Gather and return data"""
    result = {}
    for instance in self.wanted_instances:
      remote_info = rpc.call_instance_info(instance.primary_node,
                                                instance.name)
      if remote_info and "state" in remote_info:
        remote_state = "up"
      else:
        remote_state = "down"
      if instance.status == "down":
        config_state = "down"
      else:
        config_state = "up"

      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,
        "memory": instance.memory,
        "nics": [(nic.mac, nic.ip, nic.bridge) for nic in instance.nics],
        "disks": disks,
        "network_port": instance.network_port,
        "vcpus": instance.vcpus,
        }

      result[instance.name] = idict

    return result


class LUSetInstanceParms(LogicalUnit):
  """Modifies an instances's parameters.

  """
  HPATH = "instance-modify"
  HTYPE = constants.HTYPE_INSTANCE
  _OP_REQP = ["instance_name"]

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

    This runs on the master, primary and secondaries.

    """
    args = dict()
    if self.mem:
      args['memory'] = self.mem
    if self.vcpus:
      args['vcpus'] = self.vcpus
    if self.do_ip or self.do_bridge:
      if self.do_ip:
        ip = self.ip
      else:
        ip = self.instance.nics[0].ip
      if self.bridge:
        bridge = self.bridge
      else:
        bridge = self.instance.nics[0].bridge
      args['nics'] = [(ip, bridge)]
    env = _BuildInstanceHookEnvByObject(self.instance, override=args)
    nl = [self.sstore.GetMasterNode(),
          self.instance.primary_node] + list(self.instance.secondary_nodes)
    return env, nl, nl

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

    This only checks the instance list against the existing names.

    """
    self.mem = getattr(self.op, "mem", None)
    self.vcpus = getattr(self.op, "vcpus", None)
    self.ip = getattr(self.op, "ip", None)
    self.mac = getattr(self.op, "mac", None)
    self.bridge = getattr(self.op, "bridge", None)
    if [self.mem, self.vcpus, self.ip, self.bridge, self.mac].count(None) == 5:
      raise errors.OpPrereqError("No changes submitted")
    if self.mem is not None:
      try:
        self.mem = int(self.mem)
      except ValueError, err:
        raise errors.OpPrereqError("Invalid memory size: %s" % str(err))
    if self.vcpus is not None:
      try:
        self.vcpus = int(self.vcpus)
      except ValueError, err:
        raise errors.OpPrereqError("Invalid vcpus number: %s" % str(err))
    if self.ip is not None:
      self.do_ip = True
      if self.ip.lower() == "none":
        self.ip = None
      else:
        if not utils.IsValidIP(self.ip):
          raise errors.OpPrereqError("Invalid IP address '%s'." % self.ip)
    else:
      self.do_ip = False
    self.do_bridge = (self.bridge is not None)
    if self.mac is not None:
      if self.cfg.IsMacInUse(self.mac):
        raise errors.OpPrereqError('MAC address %s already in use in cluster' %
                                   self.mac)
      if not utils.IsValidMac(self.mac):
        raise errors.OpPrereqError('Invalid MAC address %s' % self.mac)

    instance = self.cfg.GetInstanceInfo(
      self.cfg.ExpandInstanceName(self.op.instance_name))
    if instance is None:
      raise errors.OpPrereqError("No such instance name '%s'" %
                                 self.op.instance_name)
    self.op.instance_name = instance.name
    self.instance = instance
    return

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

    All parameters take effect only at the next restart of the instance.
    """
    result = []
    instance = self.instance
    if self.mem:
      instance.memory = self.mem
      result.append(("mem", self.mem))
    if self.vcpus:
      instance.vcpus = self.vcpus
      result.append(("vcpus",  self.vcpus))
    if self.do_ip:
      instance.nics[0].ip = self.ip
      result.append(("ip", self.ip))
    if self.bridge:
      instance.nics[0].bridge = self.bridge
      result.append(("bridge", self.bridge))
    if self.mac:
      instance.nics[0].mac = self.mac
      result.append(("mac", self.mac))

    self.cfg.AddInstance(instance)

    return result


class LUQueryExports(NoHooksLU):
  """Query the exports list

  """
  _OP_REQP = []

  def CheckPrereq(self):
    """Check that the nodelist contains only existing nodes.

    """
    self.nodes = _GetWantedNodes(self, getattr(self.op, "nodes", None))

  def Exec(self, feedback_fn):
    """Compute the list of all the exported system images.

    Returns:
      a dictionary with the structure node->(export-list)
      where export-list is a list of the instances exported on
      that node.

    """
    return rpc.call_export_list(self.nodes)


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"]

  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.instance))
    nl = [self.sstore.GetMasterNode(), self.instance.primary_node,
          self.op.target_node]
    return env, nl, nl

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

    This checks that the instance name is a valid one.

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

    # node verification
    dst_node_short = self.cfg.ExpandNodeName(self.op.target_node)
    self.dst_node = self.cfg.GetNodeInfo(dst_node_short)

    if self.dst_node is None:
      raise errors.OpPrereqError("Destination node '%s' is unknown." %
                                 self.op.target_node)
    self.op.target_node = self.dst_node.name

  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
    # shutdown the instance, unless requested not to do so
    if self.op.shutdown:
      op = opcodes.OpShutdownInstance(instance_name=instance.name)
      self.proc.ChainOpCode(op)

    vgname = self.cfg.GetVGName()

    snap_disks = []

    try:
      for disk in instance.disks:
        if disk.iv_name == "sda":
          # new_dev_name will be a snapshot of an lvm leaf of the one we passed
          new_dev_name = rpc.call_blockdev_snapshot(src_node, disk)

          if not new_dev_name:
            logger.Error("could not snapshot block device %s on node %s" %
                         (disk.logical_id[1], src_node))
          else:
            new_dev = objects.Disk(dev_type=constants.LD_LV, size=disk.size,
                                      logical_id=(vgname, new_dev_name),
                                      physical_id=(vgname, new_dev_name),
                                      iv_name=disk.iv_name)
            snap_disks.append(new_dev)

    finally:
      if self.op.shutdown:
        op = opcodes.OpStartupInstance(instance_name=instance.name,
                                       force=False)
        self.proc.ChainOpCode(op)

    # TODO: check for size

    for dev in snap_disks:
      if not rpc.call_snapshot_export(src_node, dev, dst_node.name,
                                           instance):
        logger.Error("could not export block device %s from node"
                     " %s to node %s" %
                     (dev.logical_id[1], src_node, dst_node.name))
      if not rpc.call_blockdev_remove(src_node, dev):
        logger.Error("could not remove snapshot block device %s from"
                     " node %s" % (dev.logical_id[1], src_node))

    if not rpc.call_finalize_export(dst_node.name, instance, snap_disks):
      logger.Error("could not finalize export for instance %s on node %s" %
                   (instance.name, dst_node.name))

    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.
    if nodelist:
      op = opcodes.OpQueryExports(nodes=nodelist)
      exportlist = self.proc.ChainOpCode(op)
      for node in exportlist:
        if instance.name in exportlist[node]:
          if not rpc.call_export_remove(node, instance.name):
            logger.Error("could not remove older export for instance %s"
                         " on node %s" % (instance.name, node))


class TagsLU(NoHooksLU):
  """Generic tags LU.

  This is an abstract class which is the parent of all the other tags LUs.

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

    """
    if self.op.kind == constants.TAG_CLUSTER:
      self.target = self.cfg.GetClusterInfo()
    elif 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.target = self.cfg.GetNodeInfo(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.target = self.cfg.GetInstanceInfo(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"]

  def Exec(self, feedback_fn):
    """Returns the tag list.

    """
    return self.target.GetTags()


class LUSearchTags(NoHooksLU):
  """Searches the tags for a given pattern.

  """
  _OP_REQP = ["pattern"]

  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.GetInstanceInfo(name) for name in cfg.GetInstanceList()]
    tgts.extend([("/instances/%s" % i.name, i) for i in ilist])
    nlist = [cfg.GetNodeInfo(name) for name in cfg.GetNodeList()]
    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"]

  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"]

  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.")