Synnefo » snf-ganeti

#!/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.

"""Import/export daemon.

"""

# pylint: disable-msg=C0103

# C0103: Invalid name import-export

import errno

import logging

import optparse

import os

import select

import signal

import subprocess

import sys

import time

from ganeti import constants

from ganeti import cli

from ganeti import utils

from ganeti import serializer

from ganeti import objects

from ganeti import locking

from ganeti import impexpd

#: How many lines to keep in the status file

MAX_RECENT_OUTPUT_LINES = 20

#: Don't update status file more than once every 5 seconds (unless forced)

MIN_UPDATE_INTERVAL = 5.0

#: Give child process up to 5 seconds to exit after sending a signal

CHILD_LINGER_TIMEOUT = 5.0

#: How long to wait for a connection to be established

DEFAULT_CONNECT_TIMEOUT = 60

# Global variable for options

options = None

def SetupLogging():

  """Configures the logging module.

  """

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

  stderr_handler = logging.StreamHandler()

  stderr_handler.setFormatter(formatter)

  stderr_handler.setLevel(logging.NOTSET)

  root_logger = logging.getLogger("")

  root_logger.addHandler(stderr_handler)

  if options.debug:

    root_logger.setLevel(logging.NOTSET)

  elif options.verbose:

    root_logger.setLevel(logging.INFO)

  else:

    root_logger.setLevel(logging.ERROR)

  # Create special logger for child process output

  child_logger = logging.Logger("child output")

  child_logger.addHandler(stderr_handler)

  child_logger.setLevel(logging.NOTSET)

  return child_logger

class StatusFile:

  """Status file manager.

  """

  def __init__(self, path):

    """Initializes class.

    """

    self._path = path

    self._data = objects.ImportExportStatus(ctime=time.time(),

                                            mtime=None,

                                            recent_output=[])

  def AddRecentOutput(self, line):

    """Adds a new line of recent output.

    """

    self._data.recent_output.append(line)

    # Remove old lines

    del self._data.recent_output[:-MAX_RECENT_OUTPUT_LINES]

  def SetListenPort(self, port):

    """Sets the port the daemon is listening on.

    @type port: int

    @param port: TCP/UDP port

    """

    assert isinstance(port, (int, long)) and 0 < port < 2**16

    self._data.listen_port = port

  def GetListenPort(self):

    """Returns the port the daemon is listening on.

    """

    return self._data.listen_port

  def SetConnected(self):

    """Sets the connected flag.

    """

    self._data.connected = True

  def GetConnected(self):

    """Determines whether the daemon is connected.

    """

    return self._data.connected

  def SetExitStatus(self, exit_status, error_message):

    """Sets the exit status and an error message.

    """

    # Require error message when status isn't 0

    assert exit_status == 0 or error_message

    self._data.exit_status = exit_status

    self._data.error_message = error_message

  def ExitStatusIsSuccess(self):

    """Returns whether the exit status means "success".

    """

    return not bool(self._data.error_message)

  def Update(self, force):

    """Updates the status file.

    @type force: bool

    @param force: Write status file in any case, not only when minimum interval

                  is expired

    """

    if not (force or

            self._data.mtime is None or

            time.time() > (self._data.mtime + MIN_UPDATE_INTERVAL)):

      return

    logging.debug("Updating status file %s", self._path)

    self._data.mtime = time.time()

    utils.WriteFile(self._path,

                    data=serializer.DumpJson(self._data.ToDict(), indent=True),

                    mode=0400)

def ProcessChildIO(child, socat_stderr_read_fd, status_file, child_logger,

                   signal_notify, signal_handler, mode):

  """Handles the child processes' output.

  """

  assert not (signal_handler.signum - set([signal.SIGTERM, signal.SIGINT])), \

         "Other signals are not handled in this function"

  # Buffer size 0 is important, otherwise .read() with a specified length

  # might buffer data while poll(2) won't mark its file descriptor as

  # readable again.

  socat_stderr_read = os.fdopen(socat_stderr_read_fd, "r", 0)

  child_io_proc = impexpd.ChildIOProcessor(options.debug, status_file,

                                           child_logger)

  try:

    fdmap = {

      child.stderr.fileno():

        (child.stderr, child_io_proc.GetLineSplitter(impexpd.PROG_OTHER)),

      socat_stderr_read.fileno():

        (socat_stderr_read, child_io_proc.GetLineSplitter(impexpd.PROG_SOCAT)),

      signal_notify.fileno(): (signal_notify, None),

      }

    poller = select.poll()

    for fd in fdmap:

      utils.SetNonblockFlag(fd, True)

      poller.register(fd, select.POLLIN)

    if options.connect_timeout and mode == constants.IEM_IMPORT:

      listen_timeout = locking.RunningTimeout(options.connect_timeout, True)

    else:

      listen_timeout = None

    exit_timeout = None

    while True:

      # Break out of loop if only signal notify FD is left

      if len(fdmap) == 1 and signal_notify.fileno() in fdmap:

        break

      timeout = None

      if listen_timeout and not exit_timeout:

        if status_file.GetConnected():

          listen_timeout = None

        elif listen_timeout.Remaining() < 0:

          logging.info("Child process didn't establish connection in time")

          child.Kill(signal.SIGTERM)

          exit_timeout = \

            locking.RunningTimeout(CHILD_LINGER_TIMEOUT, True)

          # Next block will calculate timeout

        else:

          # Not yet connected, check again in a second

          timeout = 1000

      if exit_timeout:

        timeout = exit_timeout.Remaining() * 1000

        if timeout < 0:

          logging.info("Child process didn't exit in time")

          break

      for fd, event in utils.RetryOnSignal(poller.poll, timeout):

        if event & (select.POLLIN | event & select.POLLPRI):

          (from_, to) = fdmap[fd]

          # Read up to 1 KB of data

          data = from_.read(1024)

          if data:

            if to:

              to.write(data)

            elif fd == signal_notify.fileno():

              # Signal handling

              if signal_handler.called:

                signal_handler.Clear()

                if exit_timeout:

                  logging.info("Child process still has about %0.2f seconds"

                               " to exit", exit_timeout.Remaining())

                else:

                  logging.info("Giving child process %0.2f seconds to exit",

                               CHILD_LINGER_TIMEOUT)

                  exit_timeout = \

                    locking.RunningTimeout(CHILD_LINGER_TIMEOUT, True)

          else:

            poller.unregister(fd)

            del fdmap[fd]

        elif event & (select.POLLNVAL | select.POLLHUP |

                      select.POLLERR):

          poller.unregister(fd)

          del fdmap[fd]

      child_io_proc.FlushAll()

    # If there was a timeout calculator, we were waiting for the child to

    # finish, e.g. due to a signal

    return not bool(exit_timeout)

  finally:

    child_io_proc.CloseAll()

def ParseOptions():

  """Parses the options passed to the program.

  @return: Arguments to program

  """

  global options # pylint: disable-msg=W0603

  parser = optparse.OptionParser(usage=("%%prog <status-file> {%s|%s}" %

                                        (constants.IEM_IMPORT,

                                         constants.IEM_EXPORT)))

  parser.add_option(cli.DEBUG_OPT)

  parser.add_option(cli.VERBOSE_OPT)

  parser.add_option("--key", dest="key", action="store", type="string",

                    help="RSA key file")

  parser.add_option("--cert", dest="cert", action="store", type="string",

                    help="X509 certificate file")

  parser.add_option("--ca", dest="ca", action="store", type="string",

                    help="X509 CA file")

  parser.add_option("--bind", dest="bind", action="store", type="string",

                    help="Bind address")

  parser.add_option("--host", dest="host", action="store", type="string",

                    help="Remote hostname")

  parser.add_option("--port", dest="port", action="store", type="int",

                    help="Remote port")

  parser.add_option("--connect-retries", dest="connect_retries", action="store",

                    type="int", default=0,

                    help=("How many times the connection should be retried"

                          " (export only)"))

  parser.add_option("--connect-timeout", dest="connect_timeout", action="store",

                    type="int", default=DEFAULT_CONNECT_TIMEOUT,

                    help="Timeout for connection to be established (seconds)")

  parser.add_option("--compress", dest="compress", action="store",

                    type="choice", help="Compression method",

                    metavar="[%s]" % "|".join(constants.IEC_ALL),

                    choices=list(constants.IEC_ALL), default=constants.IEC_GZIP)

  parser.add_option("--cmd-prefix", dest="cmd_prefix", action="store",

                    type="string", help="Command prefix")

  parser.add_option("--cmd-suffix", dest="cmd_suffix", action="store",

                    type="string", help="Command suffix")

  (options, args) = parser.parse_args()

  if len(args) != 2:

    # Won't return

    parser.error("Expected exactly two arguments")

  (status_file_path, mode) = args

  if mode not in (constants.IEM_IMPORT,

                  constants.IEM_EXPORT):

    # Won't return

    parser.error("Invalid mode: %s" % mode)

  return (status_file_path, mode)

class ChildProcess(subprocess.Popen):

  def __init__(self, cmd, noclose_fds):

    """Initializes this class.

    """

    self._noclose_fds = noclose_fds

    # Not using close_fds because doing so would also close the socat stderr

    # pipe, which we still need.

    subprocess.Popen.__init__(self, cmd, shell=False, close_fds=False,

                              stderr=subprocess.PIPE, stdout=None, stdin=None,

                              preexec_fn=self._ChildPreexec)

    self._SetProcessGroup()

  def _ChildPreexec(self):

    """Called before child executable is execve'd.

    """

    # Move to separate process group. By sending a signal to its process group

    # we can kill the child process and all grandchildren.

    os.setpgid(0, 0)

    # Close almost all file descriptors

    utils.CloseFDs(noclose_fds=self._noclose_fds)

  def _SetProcessGroup(self):

    """Sets the child's process group.

    """

    assert self.pid, "Can't be called in child process"

    # Avoid race condition by setting child's process group (as good as

    # possible in Python) before sending signals to child. For an

    # explanation, see preexec function for child.

    try:

      os.setpgid(self.pid, self.pid)

    except EnvironmentError, err:

      # If the child process was faster we receive EPERM or EACCES

      if err.errno not in (errno.EPERM, errno.EACCES):

        raise

  def Kill(self, signum):

    """Sends signal to child process.

    """

    logging.info("Sending signal %s to child process", signum)

    os.killpg(self.pid, signum)

  def ForceQuit(self):

    """Ensure child process is no longer running.

    """

    # Final check if child process is still alive

    if utils.RetryOnSignal(self.poll) is None:

      logging.error("Child process still alive, sending SIGKILL")

      self.Kill(signal.SIGKILL)

      utils.RetryOnSignal(self.wait)

def main():

  """Main function.

  """

  # Option parsing

  (status_file_path, mode) = ParseOptions()

  # Configure logging

  child_logger = SetupLogging()

  status_file = StatusFile(status_file_path)

  try:

    try:

      # Pipe to receive socat's stderr output

      (socat_stderr_read_fd, socat_stderr_write_fd) = os.pipe()

      # Get child process command

      cmd_builder = impexpd.CommandBuilder(mode, options, socat_stderr_write_fd)

      cmd = cmd_builder.GetCommand()

      logging.debug("Starting command %r", cmd)

      # Start child process

      child = ChildProcess(cmd, [socat_stderr_write_fd])

      try:

        def _ForwardSignal(signum, _):

          """Forwards signals to child process.

          """

          child.Kill(signum)

        signal_wakeup = utils.SignalWakeupFd()

        try:

          # TODO: There is a race condition between starting the child and

          # handling the signals here. While there might be a way to work around

          # it by registering the handlers before starting the child and

          # deferring sent signals until the child is available, doing so can be

          # complicated.

          signal_handler = utils.SignalHandler([signal.SIGTERM, signal.SIGINT],

                                               handler_fn=_ForwardSignal,

                                               wakeup=signal_wakeup)

          try:

            # Close child's side

            utils.RetryOnSignal(os.close, socat_stderr_write_fd)

            if ProcessChildIO(child, socat_stderr_read_fd, status_file,

                              child_logger, signal_wakeup, signal_handler,

                              mode):

              # The child closed all its file descriptors and there was no

              # signal

              # TODO: Implement timeout instead of waiting indefinitely

              utils.RetryOnSignal(child.wait)

          finally:

            signal_handler.Reset()

        finally:

          signal_wakeup.Reset()

      finally:

        child.ForceQuit()

      if child.returncode == 0:

        errmsg = None

      elif child.returncode < 0:

        errmsg = "Exited due to signal %s" % (-child.returncode, )

      else:

        errmsg = "Exited with status %s" % (child.returncode, )

      status_file.SetExitStatus(child.returncode, errmsg)

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

      logging.exception("Unhandled error occurred")

      status_file.SetExitStatus(constants.EXIT_FAILURE,

                                "Unhandled error occurred: %s" % (err, ))

    if status_file.ExitStatusIsSuccess():

      sys.exit(constants.EXIT_SUCCESS)

    sys.exit(constants.EXIT_FAILURE)

  finally:

    status_file.Update(True)

if __name__ == "__main__":

  main()