cmdlib.py

#
#

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


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

# pylint: disable-msg=W0613,W0201

import os
import os.path
import 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 locking
from ganeti import constants
from ganeti import objects
from ganeti import opcodes
from ganeti import serializer


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

  Subclasses must follow these rules:
    - implement ExpandNames
    - implement CheckPrereq
    - implement Exec
    - implement BuildHooksEnv
    - redefine HPATH and HTYPE
    - optionally redefine their run requirements:
        REQ_MASTER: the LU needs to run on the master node
        REQ_WSSTORE: the LU needs a writable SimpleStore
        REQ_BGL: the LU needs to hold the Big Ganeti Lock exclusively

  Note that all commands require root permissions.

  """
  HPATH = None
  HTYPE = None
  _OP_REQP = []
  REQ_MASTER = True
  REQ_WSSTORE = False
  REQ_BGL = True

  def __init__(self, processor, op, context, 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 = context.cfg
    self.sstore = sstore
    self.context = context
    self.needed_locks = None
    self.acquired_locks = {}
    self.share_locks = dict(((i, 0) for i in locking.LEVELS))
    # Used to force good behavior when calling helper functions
    self.recalculate_locks = {}
    self.__ssh = None

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

    if not self.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 __GetSSH(self):
    """Returns the SshRunner object

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

  ssh = property(fget=__GetSSH)

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

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

    LUs which implement this method must also populate the self.needed_locks
    member, as a dict with lock levels as keys, and a list of needed lock names
    as values. Rules:
      - Use an empty dict if you don't need any lock
      - If you don't need any lock at a particular level omit that level
      - Don't put anything for the BGL level
      - If you want all locks at a level use None as a value
        (this reflects what LockSet does, and will be replaced before
        CheckPrereq with the full list of nodes that have been locked)

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

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

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

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

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

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

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

    """

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

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

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

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

    """
    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.

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

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

    """
    raise NotImplementedError

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

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

    Args:
      phase: the hooks phase that has just been run
      hooks_results: the results of the multi-node hooks rpc call
      feedback_fn: function to send feedback back to the caller
      lu_result: the previous result this LU had, or None in the PRE phase.

    """
    return lu_result

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

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

    """
    if self.needed_locks is None:
      self.needed_locks = {}
    else:
      assert locking.LEVEL_INSTANCE not in self.needed_locks, \
        "_ExpandAndLockInstance called with instance-level locks set"
    expanded_name = self.cfg.ExpandInstanceName(self.op.instance_name)
    if expanded_name is None:
      raise errors.OpPrereqError("Instance '%s' not known" %
                                  self.op.instance_name)
    self.needed_locks[locking.LEVEL_INSTANCE] = expanded_name
    self.op.instance_name = expanded_name

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

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

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

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

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

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

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

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

    # For now we'll replace self.needed_locks[locking.LEVEL_NODE], but in the
    # future we might want to have different behaviors depending on the value
    # of self.recalculate_locks[locking.LEVEL_NODE]
    wanted_nodes = []
    for instance_name in self.acquired_locks[locking.LEVEL_INSTANCE]:
      instance = self.context.cfg.GetInstanceInfo(instance_name)
      wanted_nodes.append(instance.primary_node)
      wanted_nodes.extend(instance.secondary_nodes)
    self.needed_locks[locking.LEVEL_NODE] = wanted_nodes

    del self.recalculate_locks[locking.LEVEL_NODE]


class NoHooksLU(LogicalUnit):
  """Simple LU which runs no hooks.

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

  """
  HPATH = None
  HTYPE = None


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, mac) in enumerate(nics):
      if ip is None:
        ip = ""
      env["INSTANCE_NIC%d_IP" % idx] = ip
      env["INSTANCE_NIC%d_BRIDGE" % idx] = bridge
      env["INSTANCE_NIC%d_HWADDR" % idx] = mac
  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, nic.mac) for nic in instance.nics],
  }
  if override:
    args.update(override)
  return _BuildInstanceHookEnv(**args)


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 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()
    if not rpc.call_node_stop_master(master, False):
      raise errors.OpExecError("Could not disable the master role")
    priv_key, pub_key, _ = ssh.GetUserFiles(constants.GANETI_RUNAS)
    utils.CreateBackup(priv_key)
    utils.CreateBackup(pub_key)
    return master


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

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

  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 = utils.CheckVolumeGroupSize(vglist, self.cfg.GetVGName(),
                                            constants.MIN_VG_SIZE)
      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 ssh connectivity data")
    else:
      if node_result['nodelist']:
        bad = True
        for node in node_result['nodelist']:
          feedback_fn("  - ERROR: ssh communication with node '%s': %s" %
                          (node, node_result['nodelist'][node]))
    if 'node-net-test' not in node_result:
      bad = True
      feedback_fn("  - ERROR: node hasn't returned node tcp connectivity data")
    else:
      if node_result['node-net-test']:
        bad = True
        nlist = utils.NiceSort(node_result['node-net-test'].keys())
        for node in nlist:
          feedback_fn("  - ERROR: tcp communication with node '%s': %s" %
                          (node, node_result['node-net-test'][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, instanceconfig, 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

    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 (node_current not in node_instance or
          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 _VerifyNPlusOneMemory(self, node_info, instance_cfg, feedback_fn):
    """Verify N+1 Memory Resilience.

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

    """
    bad = False

    for node, nodeinfo in node_info.iteritems():
      # This code checks that every node which is now listed as secondary has
      # enough memory to host all instances it is supposed to should a single
      # other node in the cluster fail.
      # FIXME: not ready for failover to an arbitrary node
      # FIXME: does not support file-backed instances
      # WARNING: we currently take into account down instances as well as up
      # ones, considering that even if they're down someone might want to start
      # them even in the event of a node failure.
      for prinode, instances in nodeinfo['sinst-by-pnode'].iteritems():
        needed_mem = 0
        for instance in instances:
          needed_mem += instance_cfg[instance].memory
        if nodeinfo['mfree'] < needed_mem:
          feedback_fn("  - ERROR: not enough memory on node %s to accomodate"
                      " failovers should node %s fail" % (node, prinode))
          bad = True
    return bad

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

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

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

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

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

    """
    all_nodes = self.cfg.GetNodeList()
    # TODO: populate the environment with useful information for verify hooks
    env = {}
    return env, [], all_nodes

  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())
    nodeinfo = [self.cfg.GetNodeInfo(nname) for nname in nodelist]
    instancelist = utils.NiceSort(self.cfg.GetInstanceList())
    i_non_redundant = [] # Non redundant instances
    node_volume = {}
    node_instance = {}
    node_info = {}
    instance_cfg = {}

    # 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,
      'node-net-test': [(node.name, node.primary_ip, node.secondary_ip)
                        for node in nodeinfo]
      }
    all_nvinfo = rpc.call_node_verify(nodelist, node_verify_param)
    all_rversion = rpc.call_version(nodelist)
    all_ninfo = rpc.call_node_info(nodelist, self.cfg.GetVGName())

    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 isinstance(volumeinfo, basestring):
        feedback_fn("  - ERROR: LVM problem on node %s: %s" %
                    (node, volumeinfo[-400:].encode('string_escape')))
        bad = True
        node_volume[node] = {}
      elif not isinstance(volumeinfo, dict):
        feedback_fn("  - ERROR: connection to %s failed" % (node,))
        bad = True
        continue
      else:
        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_info
      nodeinfo = all_ninfo[node]
      if not isinstance(nodeinfo, dict):
        feedback_fn("  - ERROR: connection to %s failed" % (node,))
        bad = True
        continue

      try:
        node_info[node] = {
          "mfree": int(nodeinfo['memory_free']),
          "dfree": int(nodeinfo['vg_free']),
          "pinst": [],
          "sinst": [],
          # dictionary holding all instances this node is secondary for,
          # grouped by their primary node. Each key is a cluster node, and each
          # value is a list of instances which have the key as primary and the
          # current node as secondary.  this is handy to calculate N+1 memory
          # availability if you can only failover from a primary to its
          # secondary.
          "sinst-by-pnode": {},
        }
      except ValueError:
        feedback_fn("  - ERROR: invalid value returned from node %s" % (node,))
        bad = True
        continue

    node_vol_should = {}

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

      inst_config.MapLVsByNode(node_vol_should)

      instance_cfg[instance] = inst_config

      pnode = inst_config.primary_node
      if pnode in node_info:
        node_info[pnode]['pinst'].append(instance)
      else:
        feedback_fn("  - ERROR: instance %s, connection to primary node"
                    " %s failed" % (instance, pnode))
        bad = True

      # If the instance is non-redundant we cannot survive losing its primary
      # node, so we are not N+1 compliant. On the other hand we have no disk
      # templates with more than one secondary so that situation is not well
      # supported either.
      # FIXME: does not support file-backed instances
      if len(inst_config.secondary_nodes) == 0:
        i_non_redundant.append(instance)
      elif len(inst_config.secondary_nodes) > 1:
        feedback_fn("  - WARNING: multiple secondaries for instance %s"
                    % instance)

      for snode in inst_config.secondary_nodes:
        if snode in node_info:
          node_info[snode]['sinst'].append(instance)
          if pnode not in node_info[snode]['sinst-by-pnode']:
            node_info[snode]['sinst-by-pnode'][pnode] = []
          node_info[snode]['sinst-by-pnode'][pnode].append(instance)
        else:
          feedback_fn("  - ERROR: instance %s, connection to secondary node"
                      " %s failed" % (instance, snode))

    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

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

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

    return not bad

  def HooksCallBack(self, phase, hooks_results, feedback_fn, lu_result):
    """Analize the post-hooks' result, handle it, and send some
    nicely-formatted feedback back to the user.

    Args:
      phase: the hooks phase that has just been run
      hooks_results: the results of the multi-node hooks rpc call
      feedback_fn: function to send feedback back to the caller
      lu_result: previous Exec result

    """
    # We only really run POST phase hooks, and are only interested in
    # their results
    if phase == constants.HOOKS_PHASE_POST:
      # Used to change hooks' output to proper indentation
      indent_re = re.compile('^', re.M)
      feedback_fn("* Hooks Results")
      if not hooks_results:
        feedback_fn("  - ERROR: general communication failure")
        lu_result = 1
      else:
        for node_name in hooks_results:
          show_node_header = True
          res = hooks_results[node_name]
          if res is False or not isinstance(res, list):
            feedback_fn("    Communication failure")
            lu_result = 1
            continue
          for script, hkr, output in res:
            if hkr == constants.HKR_FAIL:
              # The node header is only shown once, if there are
              # failing hooks on that node
              if show_node_header:
                feedback_fn("  Node %s:" % node_name)
                show_node_header = False
              feedback_fn("    ERROR: Script %s failed, output:" % script)
              output = indent_re.sub('      ', output)
              feedback_fn("%s" % output)
              lu_result = 1

      return lu_result


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

  """
  _OP_REQP = []

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

    This has no prerequisites.

    """
    pass

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

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

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

    nv_dict = {}
    for inst in instances:
      inst_lvs = {}
      if (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 isinstance(lvs, basestring):
        logger.Info("error enumerating LVs on node %s: %s" % (node, lvs))
        res_nlvm[node] = lvs
      elif 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():
        inst = nv_dict.pop((node, lv_name), None)
        if (not lv_online and inst is not None
            and inst.name not in res_instances):
          res_instances.append(inst.name)

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

    return result


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

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

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

    """
    env = {
      "OP_TARGET": self.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:
      if utils.TcpPing(new_ip, constants.DEFAULT_NODED_PORT):
        raise errors.OpPrereqError("The given cluster IP address (%s) is"
                                   " reachable on the network. Aborting." %
                                   new_ip)

    self.op.name = new_name

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

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

    # shutdown the master IP
    master = ss.GetMasterNode()
    if not rpc.call_node_stop_master(master, False):
      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, False):
        logger.Error("Could not re-enable the master role on the master,"
                     " please restart manually.")


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

  Args:
    disk: ganeti.objects.Disk object

  Returns:
    boolean indicating whether a LD_LV dev_type was found or not

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


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

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

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

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

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

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

    """
    if not self.op.vg_name:
      instances = [self.cfg.GetInstanceInfo(name)
                   for name in self.cfg.GetInstanceList()]
      for inst in instances:
        for disk in inst.disks:
          if _RecursiveCheckIfLVMBased(disk):
            raise errors.OpPrereqError("Cannot disable lvm storage while"
                                       " lvm-based instances exist")

    # if vg_name not None, checks given volume group on all nodes
    if self.op.vg_name:
      node_list = self.cfg.GetNodeList()
      vglist = rpc.call_vg_list(node_list)
      for node in node_list:
        vgstatus = utils.CheckVolumeGroupSize(vglist[node], self.op.vg_name,
                                              constants.MIN_VG_SIZE)
        if vgstatus:
          raise errors.OpPrereqError("Error on node '%s': %s" %
                                     (node, vgstatus))

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

    """
    if self.op.vg_name != self.cfg.GetVGName():
      self.cfg.SetVGName(self.op.vg_name)
    else:
      feedback_fn("Cluster LVM configuration already in desired"
                  " state, not changing")


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

    time.sleep(min(60, max_time))

  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("Node %s: Disk degraded, not found or node down" % 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 = ["output_fields", "names"]
  REQ_BGL = False

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

    self.dynamic_fields = frozenset(["name", "valid", "node_status"])
    _CheckOutputFields(static=[],
                       dynamic=self.dynamic_fields,
                       selected=self.op.output_fields)

    # Lock all nodes, in shared mode
    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1
    self.needed_locks[locking.LEVEL_NODE] = None

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

    """

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

      Args:
        node_list: a list with the names of all nodes
        rlist: a map with node names as keys and OS objects as values

      Returns:
        map: a map with osnames as keys and as value another map, with
             nodes as
             keys and list of OS objects as values
             e.g. {"debian-etch": {"node1": [<object>,...],
                                   "node2": [<object>,]}
                  }

    """
    all_os = {}
    for node_name, nr in rlist.iteritems():
      if not nr:
        continue
      for os_obj in nr:
        if os_obj.name not in all_os:
          # build a list of nodes for this os containing empty lists
          # for each node in node_list
          all_os[os_obj.name] = {}
          for nname in node_list:
            all_os[os_obj.name][nname] = []
        all_os[os_obj.name][node_name].append(os_obj)
    return all_os

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

    """
    node_list = self.acquired_locks[locking.LEVEL_NODE]
    node_data = rpc.call_os_diagnose(node_list)
    if node_data == False:
      raise errors.OpExecError("Can't gather the list of OSes")
    pol = self._DiagnoseByOS(node_list, node_data)
    output = []
    for os_name, os_data in pol.iteritems():
      row = []
      for field in self.op.output_fields:
        if field == "name":
          val = os_name
        elif field == "valid":
          val = utils.all([osl and osl[0] for osl in os_data.values()])
        elif field == "node_status":
          val = {}
          for node_name, nos_list in os_data.iteritems():
            val[node_name] = [(v.status, v.path) for v in nos_list]
        else:
          raise errors.ParameterError(field)
        row.append(val)
      output.append(row)

    return output


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

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

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

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

    """
    env = {
      "OP_TARGET": self.op.node_name,
      "NODE_NAME": self.op.node_name,
      }
    all_nodes = self.cfg.GetNodeList()
    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)

    self.context.RemoveNode(node.name)

    rpc.call_node_leave_cluster(node.name)


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

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

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

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

    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1
    # TODO: we could lock nodes only if the user asked for dynamic fields. For
    # that we need atomic ways to get info for a group of nodes from the
    # config, though.
    if not self.op.names:
      self.needed_locks[locking.LEVEL_NODE] = None
    else:
      self.needed_locks[locking.LEVEL_NODE] = \
        _GetWantedNodes(self, self.op.names)

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

    """
    # This of course is valid only if we locked the nodes
    self.wanted = self.acquired_locks[locking.LEVEL_NODE]

  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']),
            "ctotal": utils.TryConvert(int, nodeinfo['cpu_total']),
            "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 == "tags":
          val = list(node.GetTags())
        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"]
  REQ_BGL = False

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

    self.needed_locks = {}
    self.share_locks[locking.LEVEL_NODE] = 1
    if not self.op.nodes:
      self.needed_locks[locking.LEVEL_NODE] = None
    else:
      self.needed_locks[locking.LEVEL_NODE] = \
        _GetWantedNodes(self, self.op.nodes)

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

    This checks that the fields required are valid output fields.

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