Synnefo » snf-ganeti

#!/usr/bin/python

#

# 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.

"""Tool to restart erronously downed virtual machines.

This program and set of classes implement a watchdog to restart

virtual machines in a Ganeti cluster that have crashed or been killed

by a node reboot.  Run from cron or similar.

"""

# pylint: disable-msg=C0103,W0142

# C0103: Invalid name ganeti-watcher

import os

import sys

import time

import logging

from optparse import OptionParser

from ganeti import utils

from ganeti import constants

from ganeti import serializer

from ganeti import errors

from ganeti import opcodes

from ganeti import cli

from ganeti import luxi

MAXTRIES = 5

BAD_STATES = ['ERROR_down']

HELPLESS_STATES = ['ERROR_nodedown', 'ERROR_nodeoffline']

NOTICE = 'NOTICE'

ERROR = 'ERROR'

KEY_RESTART_COUNT = "restart_count"

KEY_RESTART_WHEN = "restart_when"

KEY_BOOT_ID = "bootid"

# Global client object

client = None

class NotMasterError(errors.GenericError):

  """Exception raised when this host is not the master."""

def ShouldPause():

  """Check whether we should pause.

  """

  return bool(utils.ReadWatcherPauseFile(constants.WATCHER_PAUSEFILE))

def StartNodeDaemons():

  """Start all the daemons that should be running on all nodes.

  """

  # on master or not, try to start the node dameon

  utils.EnsureDaemon(constants.NODED)

  # start confd as well. On non candidates it will be in disabled mode.

  utils.EnsureDaemon(constants.CONFD)

def RunWatcherHooks():

  """Run the watcher hooks.

  """

  hooks_dir = utils.PathJoin(constants.HOOKS_BASE_DIR,

                             constants.HOOKS_NAME_WATCHER)

  try:

    results = utils.RunParts(hooks_dir)

  except Exception, msg: # pylint: disable-msg=W0703

    logging.critical("RunParts %s failed: %s", hooks_dir, msg)

  for (relname, status, runresult) in results:

    if status == constants.RUNPARTS_SKIP:

      logging.debug("Watcher hook %s: skipped", relname)

    elif status == constants.RUNPARTS_ERR:

      logging.warning("Watcher hook %s: error (%s)", relname, runresult)

    elif status == constants.RUNPARTS_RUN:

      if runresult.failed:

        logging.warning("Watcher hook %s: failed (exit: %d) (output: %s)",

                        relname, runresult.exit_code, runresult.output)

      else:

        logging.debug("Watcher hook %s: success (output: %s)", relname,

                      runresult.output)

class WatcherState(object):

  """Interface to a state file recording restart attempts.

  """

  def __init__(self, statefile):

    """Open, lock, read and parse the file.

    @type statefile: file

    @param statefile: State file object

    """

    self.statefile = statefile

    try:

      state_data = self.statefile.read()

      if not state_data:

        self._data = {}

      else:

        self._data = serializer.Load(state_data)

    except Exception, msg: # pylint: disable-msg=W0703

      # Ignore errors while loading the file and treat it as empty

      self._data = {}

      logging.warning(("Invalid state file. Using defaults."

                       " Error message: %s"), msg)

    if "instance" not in self._data:

      self._data["instance"] = {}

    if "node" not in self._data:

      self._data["node"] = {}

    self._orig_data = serializer.Dump(self._data)

  def Save(self):

    """Save state to file, then unlock and close it.

    """

    assert self.statefile

    serialized_form = serializer.Dump(self._data)

    if self._orig_data == serialized_form:

      logging.debug("Data didn't change, just touching status file")

      os.utime(constants.WATCHER_STATEFILE, None)

      return

    # We need to make sure the file is locked before renaming it, otherwise

    # starting ganeti-watcher again at the same time will create a conflict.

    fd = utils.WriteFile(constants.WATCHER_STATEFILE,

                         data=serialized_form,

                         prewrite=utils.LockFile, close=False)

    self.statefile = os.fdopen(fd, 'w+')

  def Close(self):

    """Unlock configuration file and close it.

    """

    assert self.statefile

    # Files are automatically unlocked when closing them

    self.statefile.close()

    self.statefile = None

  def GetNodeBootID(self, name):

    """Returns the last boot ID of a node or None.

    """

    ndata = self._data["node"]

    if name in ndata and KEY_BOOT_ID in ndata[name]:

      return ndata[name][KEY_BOOT_ID]

    return None

  def SetNodeBootID(self, name, bootid):

    """Sets the boot ID of a node.

    """

    assert bootid

    ndata = self._data["node"]

    if name not in ndata:

      ndata[name] = {}

    ndata[name][KEY_BOOT_ID] = bootid

  def NumberOfRestartAttempts(self, instance):

    """Returns number of previous restart attempts.

    @type instance: L{Instance}

    @param instance: the instance to look up

    """

    idata = self._data["instance"]

    if instance.name in idata:

      return idata[instance.name][KEY_RESTART_COUNT]

    return 0

  def RecordRestartAttempt(self, instance):

    """Record a restart attempt.

    @type instance: L{Instance}

    @param instance: the instance being restarted

    """

    idata = self._data["instance"]

    if instance.name not in idata:

      inst = idata[instance.name] = {}

    else:

      inst = idata[instance.name]

    inst[KEY_RESTART_WHEN] = time.time()

    inst[KEY_RESTART_COUNT] = inst.get(KEY_RESTART_COUNT, 0) + 1

  def RemoveInstance(self, instance):

    """Update state to reflect that a machine is running.

    This method removes the record for a named instance (as we only

    track down instances).

    @type instance: L{Instance}

    @param instance: the instance to remove from books

    """

    idata = self._data["instance"]

    if instance.name in idata:

      del idata[instance.name]

class Instance(object):

  """Abstraction for a Virtual Machine instance.

  """

  def __init__(self, name, state, autostart):

    self.name = name

    self.state = state

    self.autostart = autostart

  def Restart(self):

    """Encapsulates the start of an instance.

    """

    op = opcodes.OpStartupInstance(instance_name=self.name, force=False)

    cli.SubmitOpCode(op, cl=client)

  def ActivateDisks(self):

    """Encapsulates the activation of all disks of an instance.

    """

    op = opcodes.OpActivateInstanceDisks(instance_name=self.name)

    cli.SubmitOpCode(op, cl=client)

def GetClusterData():

  """Get a list of instances on this cluster.

  """

  op1_fields = ["name", "status", "admin_state", "snodes"]

  op1 = opcodes.OpQueryInstances(output_fields=op1_fields, names=[],

                                 use_locking=True)

  op2_fields = ["name", "bootid", "offline"]

  op2 = opcodes.OpQueryNodes(output_fields=op2_fields, names=[],

                             use_locking=True)

  job_id = client.SubmitJob([op1, op2])

  all_results = cli.PollJob(job_id, cl=client, feedback_fn=logging.debug)

  logging.debug("Got data from cluster, writing instance status file")

  result = all_results[0]

  smap = {}

  instances = {}

  # write the upfile

  up_data = "".join(["%s %s\n" % (fields[0], fields[1]) for fields in result])

  utils.WriteFile(file_name=constants.INSTANCE_UPFILE, data=up_data)

  for fields in result:

    (name, status, autostart, snodes) = fields

    # update the secondary node map

    for node in snodes:

      if node not in smap:

        smap[node] = []

      smap[node].append(name)

    instances[name] = Instance(name, status, autostart)

  nodes =  dict([(name, (bootid, offline))

                 for name, bootid, offline in all_results[1]])

  client.ArchiveJob(job_id)

  return instances, nodes, smap

class Watcher(object):

  """Encapsulate the logic for restarting erronously halted virtual machines.

  The calling program should periodically instantiate me and call Run().

  This will traverse the list of instances, and make up to MAXTRIES attempts

  to restart machines that are down.

  """

  def __init__(self, opts, notepad):

    self.notepad = notepad

    master = client.QueryConfigValues(["master_node"])[0]

    if master != utils.HostInfo().name:

      raise NotMasterError("This is not the master node")

    # first archive old jobs

    self.ArchiveJobs(opts.job_age)

    # and only then submit new ones

    self.instances, self.bootids, self.smap = GetClusterData()

    self.started_instances = set()

    self.opts = opts

  def Run(self):

    """Watcher run sequence.

    """

    notepad = self.notepad

    self.CheckInstances(notepad)

    self.CheckDisks(notepad)

    self.VerifyDisks()

  @staticmethod

  def ArchiveJobs(age):

    """Archive old jobs.

    """

    arch_count, left_count = client.AutoArchiveJobs(age)

    logging.debug("Archived %s jobs, left %s", arch_count, left_count)

  def CheckDisks(self, notepad):

    """Check all nodes for restarted ones.

    """

    check_nodes = []

    for name, (new_id, offline) in self.bootids.iteritems():

      old = notepad.GetNodeBootID(name)

      if new_id is None:

        # Bad node, not returning a boot id

        if not offline:

          logging.debug("Node %s missing boot id, skipping secondary checks",

                        name)

        continue

      if old != new_id:

        # Node's boot ID has changed, proably through a reboot.

        check_nodes.append(name)

    if check_nodes:

      # Activate disks for all instances with any of the checked nodes as a

      # secondary node.

      for node in check_nodes:

        if node not in self.smap:

          continue

        for instance_name in self.smap[node]:

          instance = self.instances[instance_name]

          if not instance.autostart:

            logging.info(("Skipping disk activation for non-autostart"

                          " instance %s"), instance.name)

            continue

          if instance.name in self.started_instances:

            # we already tried to start the instance, which should have

            # activated its drives (if they can be at all)

            continue

          try:

            logging.info("Activating disks for instance %s", instance.name)

            instance.ActivateDisks()

          except Exception: # pylint: disable-msg=W0703

            logging.exception("Error while activating disks for instance %s",

                              instance.name)

      # Keep changed boot IDs

      for name in check_nodes:

        notepad.SetNodeBootID(name, self.bootids[name][0])

  def CheckInstances(self, notepad):

    """Make a pass over the list of instances, restarting downed ones.

    """

    for instance in self.instances.values():

      if instance.state in BAD_STATES:

        n = notepad.NumberOfRestartAttempts(instance)

        if n > MAXTRIES:

          # stay quiet.

          continue

        elif n < MAXTRIES:

          last = " (Attempt #%d)" % (n + 1)

        else:

          notepad.RecordRestartAttempt(instance)

          logging.error("Could not restart %s after %d attempts, giving up",

                        instance.name, MAXTRIES)

          continue

        try:

          logging.info("Restarting %s%s",

                        instance.name, last)

          instance.Restart()

          self.started_instances.add(instance.name)

        except Exception: # pylint: disable-msg=W0703

          logging.exception("Error while restarting instance %s",

                            instance.name)

        notepad.RecordRestartAttempt(instance)

      elif instance.state in HELPLESS_STATES:

        if notepad.NumberOfRestartAttempts(instance):

          notepad.RemoveInstance(instance)

      else:

        if notepad.NumberOfRestartAttempts(instance):

          notepad.RemoveInstance(instance)

          logging.info("Restart of %s succeeded", instance.name)

  @staticmethod

  def VerifyDisks():

    """Run gnt-cluster verify-disks.

    """

    op = opcodes.OpVerifyDisks()

    job_id = client.SubmitJob([op])

    result = cli.PollJob(job_id, cl=client, feedback_fn=logging.debug)[0]

    client.ArchiveJob(job_id)

    if not isinstance(result, (tuple, list)):

      logging.error("Can't get a valid result from verify-disks")

      return

    offline_disk_instances = result[2]

    if not offline_disk_instances:

      # nothing to do

      return

    logging.debug("Will activate disks for instances %s",

                  utils.CommaJoin(offline_disk_instances))

    # we submit only one job, and wait for it. not optimal, but spams

    # less the job queue

    job = [opcodes.OpActivateInstanceDisks(instance_name=name)

           for name in offline_disk_instances]

    job_id = cli.SendJob(job, cl=client)

    try:

      cli.PollJob(job_id, cl=client, feedback_fn=logging.debug)

    except Exception: # pylint: disable-msg=W0703

      logging.exception("Error while activating disks")

def OpenStateFile(path):

  """Opens the state file and acquires a lock on it.

  @type path: string

  @param path: Path to state file

  """

  # The two-step dance below is necessary to allow both opening existing

  # file read/write and creating if not existing. Vanilla open will truncate

  # an existing file -or- allow creating if not existing.

  statefile_fd = os.open(path, os.O_RDWR | os.O_CREAT)

  # Try to acquire lock on state file. If this fails, another watcher instance

  # might already be running or another program is temporarily blocking the

  # watcher from running.

  try:

    utils.LockFile(statefile_fd)

  except errors.LockError, err:

    logging.error("Can't acquire lock on state file %s: %s", path, err)

    return None

  return os.fdopen(statefile_fd, "w+")

def ParseOptions():

  """Parse the command line options.

  @return: (options, args) as from OptionParser.parse_args()

  """

  parser = OptionParser(description="Ganeti cluster watcher",

                        usage="%prog [-d]",

                        version="%%prog (ganeti) %s" %

                        constants.RELEASE_VERSION)

  parser.add_option(cli.DEBUG_OPT)

  parser.add_option("-A", "--job-age", dest="job_age",

                    help="Autoarchive jobs older than this age (default"

                    " 6 hours)", default=6*3600)

  options, args = parser.parse_args()

  options.job_age = cli.ParseTimespec(options.job_age)

  return options, args

def main():

  """Main function.

  """

  global client # pylint: disable-msg=W0603

  options, args = ParseOptions()

  if args: # watcher doesn't take any arguments

    print >> sys.stderr, ("Usage: %s [-f] " % sys.argv[0])

    sys.exit(constants.EXIT_FAILURE)

  utils.SetupLogging(constants.LOG_WATCHER, debug=options.debug,

                     stderr_logging=options.debug)

  if ShouldPause():

    logging.debug("Pause has been set, exiting")

    sys.exit(constants.EXIT_SUCCESS)

  statefile = OpenStateFile(constants.WATCHER_STATEFILE)

  if not statefile:

    sys.exit(constants.EXIT_FAILURE)

  update_file = False

  try:

    StartNodeDaemons()

    RunWatcherHooks()

    notepad = WatcherState(statefile)

    try:

      try:

        client = cli.GetClient()

      except errors.OpPrereqError:

        # this is, from cli.GetClient, a not-master case

        logging.debug("Not on master, exiting")

        update_file = True

        sys.exit(constants.EXIT_SUCCESS)

      except luxi.NoMasterError, err:

        logging.warning("Master seems to be down (%s), trying to restart",

                        str(err))

        if not utils.EnsureDaemon(constants.MASTERD):

          logging.critical("Can't start the master, exiting")

          sys.exit(constants.EXIT_FAILURE)

        # else retry the connection

        client = cli.GetClient()

      # we are on master now

      utils.EnsureDaemon(constants.RAPI)

      try:

        watcher = Watcher(options, notepad)

      except errors.ConfigurationError:

        # Just exit if there's no configuration

        update_file = True

        sys.exit(constants.EXIT_SUCCESS)

      watcher.Run()

      update_file = True

    finally:

      if update_file:

        notepad.Save()

      else:

        logging.debug("Not updating status file due to failure")

  except SystemExit:

    raise

  except NotMasterError:

    logging.debug("Not master, exiting")

    sys.exit(constants.EXIT_NOTMASTER)

  except errors.ResolverError, err:

    logging.error("Cannot resolve hostname '%s', exiting.", err.args[0])

    sys.exit(constants.EXIT_NODESETUP_ERROR)

  except errors.JobQueueFull:

    logging.error("Job queue is full, can't query cluster state")

  except errors.JobQueueDrainError:

    logging.error("Job queue is drained, can't maintain cluster state")

  except Exception, err:

    logging.exception(str(err))

    sys.exit(constants.EXIT_FAILURE)

if __name__ == '__main__':

  main()