cluster-merge

#!/usr/bin/python
#

# Copyright (C) 2010 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.

"""Tool to merge two or more clusters together.

The clusters have to run the same version of Ganeti!

"""

# pylint: disable-msg=C0103
# C0103: Invalid name cluster-merge

import logging
import os
import optparse
import shutil
import sys
import tempfile

from ganeti import cli
from ganeti import config
from ganeti import constants
from ganeti import errors
from ganeti import ssh
from ganeti import utils


PAUSE_PERIOD_OPT = cli.cli_option("-p", "--watcher-pause-period", default=1800,
                                  action="store", type="int",
                                  dest="pause_period",
                                  help=("Amount of time in seconds watcher"
                                        " should be suspended from running"))
_CLUSTERMERGE_ECID = "clustermerge-ecid"


def Flatten(unflattened_list):
  """Flattens a list.

  @param unflattened_list: A list of unflattened list objects.
  @return: A flattened list

  """
  flattened_list = []

  for item in unflattened_list:
    if isinstance(item, list):
      flattened_list.extend(Flatten(item))
    else:
      flattened_list.append(item)
  return flattened_list


class MergerData(object):
  """Container class to hold data used for merger.

  """
  def __init__(self, cluster, key_path, nodes, instances, config_path=None):
    """Initialize the container.

    @param cluster: The name of the cluster
    @param key_path: Path to the ssh private key used for authentication
    @param nodes: List of nodes in the merging cluster
    @param instances: List of instances running on merging cluster
    @param config_path: Path to the merging cluster config

    """
    self.cluster = cluster
    self.key_path = key_path
    self.nodes = nodes
    self.instances = instances
    self.config_path = config_path


class Merger(object):
  """Handling the merge.

  """
  def __init__(self, clusters, pause_period):
    """Initialize object with sane defaults and infos required.

    @param clusters: The list of clusters to merge in
    @param pause_period: The time watcher shall be disabled for

    """
    self.merger_data = []
    self.clusters = clusters
    self.pause_period = pause_period
    self.work_dir = tempfile.mkdtemp(suffix="cluster-merger")
    (self.cluster_name, ) = cli.GetClient().QueryConfigValues(["cluster_name"])
    self.ssh_runner = ssh.SshRunner(self.cluster_name)

  def Setup(self):
    """Sets up our end so we can do the merger.

    This method is setting us up as a preparation for the merger.
    It makes the initial contact and gathers information needed.

    @raise errors.RemoteError: for errors in communication/grabbing

    """
    (remote_path, _, _) = ssh.GetUserFiles("root")

    if self.cluster_name in self.clusters:
      raise errors.CommandError("Cannot merge cluster %s with itself" %
                                self.cluster_name)

    # Fetch remotes private key
    for cluster in self.clusters:
      result = self._RunCmd(cluster, "cat %s" % remote_path, batch=False,
                            ask_key=False)
      if result.failed:
        raise errors.RemoteError("There was an error while grabbing ssh private"
                                 " key from %s. Fail reason: %s; output: %s" %
                                 (cluster, result.fail_reason, result.output))

      key_path = utils.PathJoin(self.work_dir, cluster)
      utils.WriteFile(key_path, mode=0600, data=result.stdout)

      result = self._RunCmd(cluster, "gnt-node list -o name --no-header",
                            private_key=key_path)
      if result.failed:
        raise errors.RemoteError("Unable to retrieve list of nodes from %s."
                                 " Fail reason: %s; output: %s" %
                                 (cluster, result.fail_reason, result.output))
      nodes = result.stdout.splitlines()

      result = self._RunCmd(cluster, "gnt-instance list -o name --no-header",
                            private_key=key_path)
      if result.failed:
        raise errors.RemoteError("Unable to retrieve list of instances from"
                                 " %s. Fail reason: %s; output: %s" %
                                 (cluster, result.fail_reason, result.output))
      instances = result.stdout.splitlines()

      self.merger_data.append(MergerData(cluster, key_path, nodes, instances))

  def _PrepareAuthorizedKeys(self):
    """Prepare the authorized_keys on every merging node.

    This method add our public key to remotes authorized_key for further
    communication.

    """
    (_, pub_key_file, auth_keys) = ssh.GetUserFiles("root")
    pub_key = utils.ReadFile(pub_key_file)

    for data in self.merger_data:
      for node in data.nodes:
        result = self._RunCmd(node, ("cat >> %s << '!EOF.'\n%s!EOF.\n" %
                                     (auth_keys, pub_key)),
                              private_key=data.key_path)

        if result.failed:
          raise errors.RemoteError("Unable to add our public key to %s in %s."
                                   " Fail reason: %s; output: %s" %
                                   (node, data.cluster, result.fail_reason,
                                    result.output))

  def _RunCmd(self, hostname, command, user="root", use_cluster_key=False,
              strict_host_check=False, private_key=None, batch=True,
              ask_key=False):
    """Wrapping SshRunner.Run with default parameters.

    For explanation of parameters see L{ganeti.ssh.SshRunner.Run}.

    """
    return self.ssh_runner.Run(hostname=hostname, command=command, user=user,
                               use_cluster_key=use_cluster_key,
                               strict_host_check=strict_host_check,
                               private_key=private_key, batch=batch,
                               ask_key=ask_key)

  def _StopMergingInstances(self):
    """Stop instances on merging clusters.

    """
    for cluster in self.clusters:
      result = self._RunCmd(cluster, "gnt-instance shutdown --all"
                                     " --force-multiple")

      if result.failed:
        raise errors.RemoteError("Unable to stop instances on %s."
                                 " Fail reason: %s; output: %s" %
                                 (cluster, result.fail_reason, result.output))

  def _DisableWatcher(self):
    """Disable watch on all merging clusters, including ourself.

    """
    for cluster in ["localhost"] + self.clusters:
      result = self._RunCmd(cluster, "gnt-cluster watcher pause %d" %
                                     self.pause_period)

      if result.failed:
        raise errors.RemoteError("Unable to pause watcher on %s."
                                 " Fail reason: %s; output: %s" %
                                 (cluster, result.fail_reason, result.output))

  def _StopDaemons(self):
    """Stop all daemons on merging nodes.

    """
    cmd = "%s stop-all" % constants.DAEMON_UTIL
    for data in self.merger_data:
      for node in data.nodes:
        result = self._RunCmd(node, cmd)

        if result.failed:
          raise errors.RemoteError("Unable to stop daemons on %s."
                                   " Fail reason: %s; output: %s." %
                                   (node, result.fail_reason, result.output))

  def _FetchRemoteConfig(self):
    """Fetches and stores remote cluster config from the master.

    This step is needed before we can merge the config.

    """
    for data in self.merger_data:
      result = self._RunCmd(data.cluster, "cat %s" %
                                          constants.CLUSTER_CONF_FILE)

      if result.failed:
        raise errors.RemoteError("Unable to retrieve remote config on %s."
                                 " Fail reason: %s; output %s" %
                                 (data.cluster, result.fail_reason,
                                  result.output))

      data.config_path = utils.PathJoin(self.work_dir, "%s_config.data" %
                                        data.cluster)
      utils.WriteFile(data.config_path, data=result.stdout)

  # R0201: Method could be a function
  def _KillMasterDaemon(self): # pylint: disable-msg=R0201
    """Kills the local master daemon.

    @raise errors.CommandError: If unable to kill

    """
    result = utils.RunCmd([constants.DAEMON_UTIL, "stop-master"])
    if result.failed:
      raise errors.CommandError("Unable to stop master daemons."
                                " Fail reason: %s; output: %s" %
                                (result.fail_reason, result.output))

  def _MergeConfig(self):
    """Merges all foreign config into our own config.

    """
    my_config = config.ConfigWriter(offline=True)
    fake_ec_id = 0 # Needs to be uniq over the whole config merge

    for data in self.merger_data:
      other_config = config.ConfigWriter(data.config_path, accept_foreign=True)
      self._MergeNodeGroups(my_config, other_config)

      for node in other_config.GetNodeList():
        node_info = other_config.GetNodeInfo(node)
        node_info.master_candidate = False
        my_config.AddNode(node_info, str(fake_ec_id))
        fake_ec_id += 1

      for instance in other_config.GetInstanceList():
        instance_info = other_config.GetInstanceInfo(instance)

        # Update the DRBD port assignments
        # This is a little bit hackish
        for dsk in instance_info.disks:
          if dsk.dev_type in constants.LDS_DRBD:
            port = my_config.AllocatePort()

            logical_id = list(dsk.logical_id)
            logical_id[2] = port
            dsk.logical_id = tuple(logical_id)

            physical_id = list(dsk.physical_id)
            physical_id[1] = physical_id[3] = port
            dsk.physical_id = tuple(physical_id)

        my_config.AddInstance(instance_info, str(fake_ec_id))
        fake_ec_id += 1

  # R0201: Method could be a function
  def _MergeNodeGroups(self, my_config, other_config):
    """Adds foreign node groups

    ConfigWriter.AddNodeGroup takes care of making sure there are no conflicts.
    """
    # pylint: disable-msg=R0201
    for grp in other_config.GetAllNodeGroupsInfo().values():
      #TODO: handle node group conflicts
      my_config.AddNodeGroup(grp, _CLUSTERMERGE_ECID)

  # R0201: Method could be a function
  def _StartMasterDaemon(self, no_vote=False): # pylint: disable-msg=R0201
    """Starts the local master daemon.

    @param no_vote: Should the masterd started without voting? default: False
    @raise errors.CommandError: If unable to start daemon.

    """
    env = {}
    if no_vote:
      env["EXTRA_MASTERD_ARGS"] = "--no-voting --yes-do-it"

    result = utils.RunCmd([constants.DAEMON_UTIL, "start-master"], env=env)
    if result.failed:
      raise errors.CommandError("Couldn't start ganeti master."
                                " Fail reason: %s; output: %s" %
                                (result.fail_reason, result.output))

  def _ReaddMergedNodesAndRedist(self):
    """Readds all merging nodes and make sure their config is up-to-date.

    @raise errors.CommandError: If anything fails.

    """
    for data in self.merger_data:
      for node in data.nodes:
        result = utils.RunCmd(["gnt-node", "add", "--readd",
                               "--no-ssh-key-check", "--force-join", node])
        if result.failed:
          raise errors.CommandError("Couldn't readd node %s. Fail reason: %s;"
                                    " output: %s" % (node, result.fail_reason,
                                                     result.output))

    result = utils.RunCmd(["gnt-cluster", "redist-conf"])
    if result.failed:
      raise errors.CommandError("Redistribution failed. Fail reason: %s;"
                                " output: %s" % (result.fail_reason,
                                                result.output))

  # R0201: Method could be a function
  def _StartupAllInstances(self): # pylint: disable-msg=R0201
    """Starts up all instances (locally).

    @raise errors.CommandError: If unable to start clusters

    """
    result = utils.RunCmd(["gnt-instance", "startup", "--all",
                           "--force-multiple"])
    if result.failed:
      raise errors.CommandError("Unable to start all instances."
                                " Fail reason: %s; output: %s" %
                                (result.fail_reason, result.output))

  # R0201: Method could be a function
  def _VerifyCluster(self): # pylint: disable-msg=R0201
    """Runs gnt-cluster verify to verify the health.

    @raise errors.ProgrammError: If cluster fails on verification

    """
    result = utils.RunCmd(["gnt-cluster", "verify"])
    if result.failed:
      raise errors.CommandError("Verification of cluster failed."
                                " Fail reason: %s; output: %s" %
                                (result.fail_reason, result.output))

  def Merge(self):
    """Does the actual merge.

    It runs all the steps in the right order and updates the user about steps
    taken. Also it keeps track of rollback_steps to undo everything.

    """
    rbsteps = []
    try:
      logging.info("Pre cluster verification")
      self._VerifyCluster()

      logging.info("Prepare authorized_keys")
      rbsteps.append("Remove our key from authorized_keys on nodes:"
                     " %(nodes)s")
      self._PrepareAuthorizedKeys()

      rbsteps.append("Start all instances again on the merging"
                     " clusters: %(clusters)s")
      logging.info("Stopping merging instances (takes a while)")
      self._StopMergingInstances()

      logging.info("Disable watcher")
      self._DisableWatcher()
      logging.info("Stop daemons on merging nodes")
      self._StopDaemons()
      logging.info("Merging config")
      self._FetchRemoteConfig()

      logging.info("Stopping master daemon")
      self._KillMasterDaemon()

      rbsteps.append("Restore %s from another master candidate"
                     " and restart master daemon" %
                     constants.CLUSTER_CONF_FILE)
      self._MergeConfig()
      self._StartMasterDaemon(no_vote=True)

      # Point of no return, delete rbsteps
      del rbsteps[:]

      logging.warning("We are at the point of no return. Merge can not easily"
                      " be undone after this point.")
      logging.info("Readd nodes")
      self._ReaddMergedNodesAndRedist()

      logging.info("Merge done, restart master daemon normally")
      self._KillMasterDaemon()
      self._StartMasterDaemon()

      logging.info("Starting instances again")
      self._StartupAllInstances()
      logging.info("Post cluster verification")
      self._VerifyCluster()
    except errors.GenericError, e:
      logging.exception(e)

      if rbsteps:
        nodes = Flatten([data.nodes for data in self.merger_data])
        info = {
          "clusters": self.clusters,
          "nodes": nodes,
          }
        logging.critical("In order to rollback do the following:")
        for step in rbsteps:
          logging.critical("  * %s", step % info)
      else:
        logging.critical("Nothing to rollback.")

      # TODO: Keep track of steps done for a flawless resume?

  def Cleanup(self):
    """Clean up our environment.

    This cleans up remote private keys and configs and after that
    deletes the temporary directory.

    """
    shutil.rmtree(self.work_dir)


def SetupLogging(options):
  """Setting up logging infrastructure.

  @param options: Parsed command line options

  """
  formatter = logging.Formatter("%(asctime)s: %(levelname)s %(message)s")

  stderr_handler = logging.StreamHandler()
  stderr_handler.setFormatter(formatter)
  if options.debug:
    stderr_handler.setLevel(logging.NOTSET)
  elif options.verbose:
    stderr_handler.setLevel(logging.INFO)
  else:
    stderr_handler.setLevel(logging.ERROR)

  root_logger = logging.getLogger("")
  root_logger.setLevel(logging.NOTSET)
  root_logger.addHandler(stderr_handler)


def main():
  """Main routine.

  """
  program = os.path.basename(sys.argv[0])

  parser = optparse.OptionParser(usage=("%prog [--debug|--verbose]"
                                        " [--watcher-pause-period SECONDS]"
                                        " <cluster> <cluster...>"),
                                        prog=program)
  parser.add_option(cli.DEBUG_OPT)
  parser.add_option(cli.VERBOSE_OPT)
  parser.add_option(PAUSE_PERIOD_OPT)

  (options, args) = parser.parse_args()

  SetupLogging(options)

  if not args:
    parser.error("No clusters specified")

  cluster_merger = Merger(utils.UniqueSequence(args), options.pause_period)
  try:
    try:
      cluster_merger.Setup()
      cluster_merger.Merge()
    except errors.GenericError, e:
      logging.exception(e)
      return constants.EXIT_FAILURE
  finally:
    cluster_merger.Cleanup()

  return constants.EXIT_SUCCESS


if __name__ == "__main__":
  sys.exit(main())