ganeti-masterd

#!/usr/bin/python
#

# 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.


"""Master daemon program.

Some classes deviates from the standard style guide since the
inheritance from parent classes requires it.

"""


import os
import sys
import SocketServer
import time
import collections
import signal
import logging

from optparse import OptionParser

from ganeti import config
from ganeti import constants
from ganeti import daemon
from ganeti import mcpu
from ganeti import opcodes
from ganeti import jqueue
from ganeti import locking
from ganeti import luxi
from ganeti import utils
from ganeti import errors
from ganeti import ssconf
from ganeti import workerpool
from ganeti import rpc
from ganeti import bootstrap
from ganeti import serializer


CLIENT_REQUEST_WORKERS = 16

EXIT_NOTMASTER = constants.EXIT_NOTMASTER
EXIT_NODESETUP_ERROR = constants.EXIT_NODESETUP_ERROR


class ClientRequestWorker(workerpool.BaseWorker):
  def RunTask(self, server, request, client_address):
    """Process the request.

    This is copied from the code in ThreadingMixIn.

    """
    try:
      server.finish_request(request, client_address)
      server.close_request(request)
    except:
      server.handle_error(request, client_address)
      server.close_request(request)


class IOServer(SocketServer.UnixStreamServer):
  """IO thread class.

  This class takes care of initializing the other threads, setting
  signal handlers (which are processed only in this thread), and doing
  cleanup at shutdown.

  """
  def __init__(self, address, rqhandler):
    """IOServer constructor

    @param address: the address to bind this IOServer to
    @param rqhandler: RequestHandler type object

    """
    SocketServer.UnixStreamServer.__init__(self, address, rqhandler)

    # We'll only start threads once we've forked.
    self.context = None
    self.request_workers = None

  def setup_queue(self):
    self.context = GanetiContext()
    self.request_workers = workerpool.WorkerPool(CLIENT_REQUEST_WORKERS,
                                                 ClientRequestWorker)

  def process_request(self, request, client_address):
    """Add task to workerpool to process request.

    """
    self.request_workers.AddTask(self, request, client_address)

  @utils.SignalHandled([signal.SIGINT, signal.SIGTERM])
  def serve_forever(self, signal_handlers=None):
    """Handle one request at a time until told to quit."""
    assert isinstance(signal_handlers, dict) and \
           len(signal_handlers) > 0, \
           "Broken SignalHandled decorator"
    # Since we use SignalHandled only once, the resulting dict will map all
    # signals to the same handler. We'll just use the first one.
    sighandler = signal_handlers.values()[0]
    while not sighandler.called:
      self.handle_request()

  def server_cleanup(self):
    """Cleanup the server.

    This involves shutting down the processor threads and the master
    socket.

    """
    try:
      self.server_close()
    finally:
      if self.request_workers:
        self.request_workers.TerminateWorkers()
      if self.context:
        self.context.jobqueue.Shutdown()


class ClientRqHandler(SocketServer.BaseRequestHandler):
  """Client handler"""
  EOM = '\3'
  READ_SIZE = 4096

  def setup(self):
    self._buffer = ""
    self._msgs = collections.deque()
    self._ops = ClientOps(self.server)

  def handle(self):
    while True:
      msg = self.read_message()
      if msg is None:
        logging.debug("client closed connection")
        break

      request = serializer.LoadJson(msg)
      logging.debug("request: %s", request)
      if not isinstance(request, dict):
        logging.error("wrong request received: %s", msg)
        break

      method = request.get(luxi.KEY_METHOD, None)
      args = request.get(luxi.KEY_ARGS, None)
      if method is None or args is None:
        logging.error("no method or args in request")
        break

      success = False
      try:
        result = self._ops.handle_request(method, args)
        success = True
      except errors.GenericError, err:
        success = False
        result = errors.EncodeException(err)
      except:
        logging.error("Unexpected exception", exc_info=True)
        err = sys.exc_info()
        result = "Caught exception: %s" % str(err[1])

      response = {
        luxi.KEY_SUCCESS: success,
        luxi.KEY_RESULT: result,
        }
      logging.debug("response: %s", response)
      self.send_message(serializer.DumpJson(response))

  def read_message(self):
    while not self._msgs:
      data = self.request.recv(self.READ_SIZE)
      if not data:
        return None
      new_msgs = (self._buffer + data).split(self.EOM)
      self._buffer = new_msgs.pop()
      self._msgs.extend(new_msgs)
    return self._msgs.popleft()

  def send_message(self, msg):
    #print "sending", msg
    # TODO: sendall is not guaranteed to send everything
    self.request.sendall(msg + self.EOM)


class ClientOps:
  """Class holding high-level client operations."""
  def __init__(self, server):
    self.server = server

  def handle_request(self, method, args):
    queue = self.server.context.jobqueue

    # TODO: Parameter validation

    if method == luxi.REQ_SUBMIT_JOB:
      logging.info("Received new job")
      ops = [opcodes.OpCode.LoadOpCode(state) for state in args]
      return queue.SubmitJob(ops)

    if method == luxi.REQ_SUBMIT_MANY_JOBS:
      logging.info("Received multiple jobs")
      jobs = []
      for ops in args:
        jobs.append([opcodes.OpCode.LoadOpCode(state) for state in ops])
      return queue.SubmitManyJobs(jobs)

    elif method == luxi.REQ_CANCEL_JOB:
      job_id = args
      logging.info("Received job cancel request for %s", job_id)
      return queue.CancelJob(job_id)

    elif method == luxi.REQ_ARCHIVE_JOB:
      job_id = args
      logging.info("Received job archive request for %s", job_id)
      return queue.ArchiveJob(job_id)

    elif method == luxi.REQ_AUTOARCHIVE_JOBS:
      (age, timeout) = args
      logging.info("Received job autoarchive request for age %s, timeout %s",
                   age, timeout)
      return queue.AutoArchiveJobs(age, timeout)

    elif method == luxi.REQ_WAIT_FOR_JOB_CHANGE:
      (job_id, fields, prev_job_info, prev_log_serial, timeout) = args
      logging.info("Received job poll request for %s", job_id)
      return queue.WaitForJobChanges(job_id, fields, prev_job_info,
                                     prev_log_serial, timeout)

    elif method == luxi.REQ_QUERY_JOBS:
      (job_ids, fields) = args
      if isinstance(job_ids, (tuple, list)) and job_ids:
        msg = ", ".join(job_ids)
      else:
        msg = str(job_ids)
      logging.info("Received job query request for %s", msg)
      return queue.QueryJobs(job_ids, fields)

    elif method == luxi.REQ_QUERY_INSTANCES:
      (names, fields, use_locking) = args
      logging.info("Received instance query request for %s", names)
      if use_locking:
        raise errors.OpPrereqError("Sync queries are not allowed")
      op = opcodes.OpQueryInstances(names=names, output_fields=fields,
                                    use_locking=use_locking)
      return self._Query(op)

    elif method == luxi.REQ_QUERY_NODES:
      (names, fields, use_locking) = args
      logging.info("Received node query request for %s", names)
      if use_locking:
        raise errors.OpPrereqError("Sync queries are not allowed")
      op = opcodes.OpQueryNodes(names=names, output_fields=fields,
                                use_locking=use_locking)
      return self._Query(op)

    elif method == luxi.REQ_QUERY_EXPORTS:
      nodes, use_locking = args
      if use_locking:
        raise errors.OpPrereqError("Sync queries are not allowed")
      logging.info("Received exports query request")
      op = opcodes.OpQueryExports(nodes=nodes, use_locking=use_locking)
      return self._Query(op)

    elif method == luxi.REQ_QUERY_CONFIG_VALUES:
      fields = args
      logging.info("Received config values query request for %s", fields)
      op = opcodes.OpQueryConfigValues(output_fields=fields)
      return self._Query(op)

    elif method == luxi.REQ_QUERY_CLUSTER_INFO:
      logging.info("Received cluster info query request")
      op = opcodes.OpQueryClusterInfo()
      return self._Query(op)

    elif method == luxi.REQ_QUEUE_SET_DRAIN_FLAG:
      drain_flag = args
      logging.info("Received queue drain flag change request to %s",
                   drain_flag)
      return queue.SetDrainFlag(drain_flag)

    elif method == luxi.REQ_SET_WATCHER_PAUSE:
      (until, ) = args

      if until is None:
        logging.info("Received request to no longer pause the watcher")
      else:
        if not isinstance(until, (int, float)):
          raise TypeError("Duration must be an integer or float")

        if until < time.time():
          raise errors.GenericError("Unable to set pause end time in the past")

        logging.info("Received request to pause the watcher until %s", until)

      return _SetWatcherPause(until)

    else:
      logging.info("Received invalid request '%s'", method)
      raise ValueError("Invalid operation '%s'" % method)

  def _Query(self, op):
    """Runs the specified opcode and returns the result.

    """
    proc = mcpu.Processor(self.server.context)
    return proc.ExecOpCode(op, None)


class GanetiContext(object):
  """Context common to all ganeti threads.

  This class creates and holds common objects shared by all threads.

  """
  _instance = None

  def __init__(self):
    """Constructs a new GanetiContext object.

    There should be only a GanetiContext object at any time, so this
    function raises an error if this is not the case.

    """
    assert self.__class__._instance is None, "double GanetiContext instance"

    # Create global configuration object
    self.cfg = config.ConfigWriter()

    # Locking manager
    self.glm = locking.GanetiLockManager(
                self.cfg.GetNodeList(),
                self.cfg.GetInstanceList())

    # Job queue
    self.jobqueue = jqueue.JobQueue(self)

    # setting this also locks the class against attribute modifications
    self.__class__._instance = self

  def __setattr__(self, name, value):
    """Setting GanetiContext attributes is forbidden after initialization.

    """
    assert self.__class__._instance is None, "Attempt to modify Ganeti Context"
    object.__setattr__(self, name, value)

  def AddNode(self, node):
    """Adds a node to the configuration and lock manager.

    """
    # Add it to the configuration
    self.cfg.AddNode(node)

    # If preseeding fails it'll not be added
    self.jobqueue.AddNode(node)

    # Add the new node to the Ganeti Lock Manager
    self.glm.add(locking.LEVEL_NODE, node.name)

  def ReaddNode(self, node):
    """Updates a node that's already in the configuration

    """
    # Synchronize the queue again
    self.jobqueue.AddNode(node)

  def RemoveNode(self, name):
    """Removes a node from the configuration and lock manager.

    """
    # Remove node from configuration
    self.cfg.RemoveNode(name)

    # Notify job queue
    self.jobqueue.RemoveNode(name)

    # Remove the node from the Ganeti Lock Manager
    self.glm.remove(locking.LEVEL_NODE, name)


def _SetWatcherPause(until):
  """Creates or removes the watcher pause file.

  @type until: None or int
  @param until: Unix timestamp saying until when the watcher shouldn't run

  """
  if until is None:
    utils.RemoveFile(constants.WATCHER_PAUSEFILE)
  else:
    utils.WriteFile(constants.WATCHER_PAUSEFILE,
                    data="%d\n" % (until, ))

  return until


def CheckAgreement():
  """Check the agreement on who is the master.

  The function uses a very simple algorithm: we must get more positive
  than negative answers. Since in most of the cases we are the master,
  we'll use our own config file for getting the node list. In the
  future we could collect the current node list from our (possibly
  obsolete) known nodes.

  In order to account for cold-start of all nodes, we retry for up to
  a minute until we get a real answer as the top-voted one. If the
  nodes are more out-of-sync, for now manual startup of the master
  should be attempted.

  Note that for a even number of nodes cluster, we need at least half
  of the nodes (beside ourselves) to vote for us. This creates a
  problem on two-node clusters, since in this case we require the
  other node to be up too to confirm our status.

  """
  myself = utils.HostInfo().name
  #temp instantiation of a config writer, used only to get the node list
  cfg = config.ConfigWriter()
  node_list = cfg.GetNodeList()
  del cfg
  retries = 6
  while retries > 0:
    votes = bootstrap.GatherMasterVotes(node_list)
    if not votes:
      # empty node list, this is a one node cluster
      return True
    if votes[0][0] is None:
      retries -= 1
      time.sleep(10)
      continue
    break
  if retries == 0:
    logging.critical("Cluster inconsistent, most of the nodes didn't answer"
                     " after multiple retries. Aborting startup")
    return False
  # here a real node is at the top of the list
  all_votes = sum(item[1] for item in votes)
  top_node, top_votes = votes[0]

  result = False
  if top_node != myself:
    logging.critical("It seems we are not the master (top-voted node"
                     " is %s with %d out of %d votes)", top_node, top_votes,
                     all_votes)
  elif top_votes < all_votes - top_votes:
    logging.critical("It seems we are not the master (%d votes for,"
                     " %d votes against)", top_votes, all_votes - top_votes)
  else:
    result = True

  return result


def CheckAgreementWithRpc():
  rpc.Init()
  try:
    return CheckAgreement()
  finally:
    rpc.Shutdown()


def _RunInSeparateProcess(fn):
  """Runs a function in a separate process.

  Note: Only boolean return values are supported.

  @type fn: callable
  @param fn: Function to be called
  @rtype: bool

  """
  pid = os.fork()
  if pid == 0:
    # Child process
    try:
      # Call function
      result = int(bool(fn()))
      assert result in (0, 1)
    except:
      logging.exception("Error while calling function in separate process")
      # 0 and 1 are reserved for the return value
      result = 33

    os._exit(result)

  # Parent process

  # Avoid zombies and check exit code
  (_, status) = os.waitpid(pid, 0)

  if os.WIFSIGNALED(status):
    signum = os.WTERMSIG(status)
    exitcode = None
  else:
    signum = None
    exitcode = os.WEXITSTATUS(status)

  if not (exitcode in (0, 1) and signum is None):
    logging.error("Child program failed (code=%s, signal=%s)",
                  exitcode, signum)
    sys.exit(constants.EXIT_FAILURE)

  return bool(exitcode)


def CheckMasterd(options, args):
  """Initial checks whether to run or exit with a failure.

  """
  ssconf.CheckMaster(options.debug)

  # If CheckMaster didn't fail we believe we are the master, but we have to
  # confirm with the other nodes.
  if options.no_voting:
    if options.yes_do_it:
      return

    sys.stdout.write("The 'no voting' option has been selected.\n")
    sys.stdout.write("This is dangerous, please confirm by"
                     " typing uppercase 'yes': ")
    sys.stdout.flush()

    confirmation = sys.stdin.readline().strip()
    if confirmation != "YES":
      print >>sys.stderr, "Aborting."
      sys.exit(constants.EXIT_FAILURE)

    return

  # CheckAgreement uses RPC and threads, hence it needs to be run in a separate
  # process before we call utils.Daemonize in the current process.
  if not _RunInSeparateProcess(CheckAgreementWithRpc):
    sys.exit(constants.EXIT_FAILURE)


def ExecMasterd (options, args):
  """Main master daemon function, executed with the PID file held.

  """
  # This is safe to do as the pid file guarantees against
  # concurrent execution.
  utils.RemoveFile(constants.MASTER_SOCKET)

  master = IOServer(constants.MASTER_SOCKET, ClientRqHandler)
  try:
    rpc.Init()
    try:
      # activate ip
      master_node = ssconf.SimpleStore().GetMasterNode()
      result = rpc.RpcRunner.call_node_start_master(master_node, False, False)
      msg = result.fail_msg
      if msg:
        logging.error("Can't activate master IP address: %s", msg)

      master.setup_queue()
      try:
        master.serve_forever()
      finally:
        master.server_cleanup()
    finally:
      rpc.Shutdown()
  finally:
    utils.RemoveFile(constants.MASTER_SOCKET)


def main():
  """Main function"""
  parser = OptionParser(description="Ganeti master daemon",
                        usage="%prog [-f] [-d]",
                        version="%%prog (ganeti) %s" %
                        constants.RELEASE_VERSION)
  parser.add_option("--no-voting", dest="no_voting",
                    help="Do not check that the nodes agree on this node"
                    " being the master and start the daemon unconditionally",
                    default=False, action="store_true")
  parser.add_option("--yes-do-it", dest="yes_do_it",
                    help="Override interactive check for --no-voting",
                    default=False, action="store_true")
  dirs = [(constants.RUN_GANETI_DIR, constants.RUN_DIRS_MODE),
          (constants.SOCKET_DIR, constants.SOCKET_DIR_MODE),
         ]
  daemon.GenericMain(constants.MASTERD, parser, dirs,
                     CheckMasterd, ExecMasterd)


if __name__ == "__main__":
  main()