vcycled

#!/usr/bin/python
#
# vcycled - VM lifecycle manager daemon for OpenStack etc
#
#  Andrew McNab, Raoul Hidalgo Charman, University of Manchester.
#  Copyright (c) 2013-8. All rights reserved.
#
#  Redistribution and use in source and binary forms, with or
#  without modification, are permitted provided that the following
#  conditions are met:
#
#    o Redistributions of source code must retain the above
#      copyright notice, this list of conditions and the following
#      disclaimer.
#    o Redistributions in binary form must reproduce the above
#      copyright notice, this list of conditions and the following
#      disclaimer in the documentation and/or other materials
#      provided with the distribution.
#
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
#  CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
#  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
#  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
#  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
#  BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
#  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
#  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
#  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
#  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
#  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
#  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
#  POSSIBILITY OF SUCH DAMAGE.
#

import os
import sys
import stat
import time
import random

import vcycle

sleepSeconds = 60

#
# PROGRAM MAIN
#

if __name__ == '__main__':

  if (os.fork() != 0):
    sys.exit() # first parent

  else:
    os.chdir("/")
    os.setsid()
    os.umask(0)

    if os.fork() != 0:
      sys.exit() # second parent

    else:

      try:
        f = open('/var/run/vcycled.pid', 'w')
        f.write(str(os.getpid()) + '\n')
        f.close()
      except:
        print 'Failed to create /var/run/vcycled.pid - exiting'
        sys.exit(1)

      # Close stdin now
      si = file('/dev/null', 'r')
      os.dup2(si.fileno(), sys.stdin.fileno())

      while True:

        # Ensure /var/log/vcycle directory exists
        try:
          os.makedirs('/var/log/vcycle', stat.S_IRUSR|stat.S_IWUSR|stat.S_IXUSR|stat.S_IRGRP|stat.S_IXGRP|stat.S_IROTH|stat.S_IXOTH)
        except:
          pass

        # Close and reopen stdout->log file, in case of logrotate
        try:
          close(so)
        except:
          pass

        so = file('/var/log/vcycle/vcycled', 'a+')
        os.dup2(so.fileno(), sys.stdout.fileno())

        # Close and reopen stderr->log file, in case of logrotate
        try:
          close(se)
        except:
          pass

        se = file('/var/log/vcycle/vcycled', 'a+', 0)
        os.dup2(se.fileno(), sys.stderr.fileno())

        try:
          pf = open('/var/run/vcycled.pid', 'r')
          pid = int(pf.read().strip())
          pf.close()

          if pid != os.getpid():
            print 'new /var/run/vcycled.pid - exiting'
            break

        except:
          print 'no /var/run/vcycled.pid - exiting'
          break

        # Fork a subprocess to run each cycle
        cyclePid = os.fork()

        # Otherwise each subprocess starts from the same point in the sequence!
        random.seed()

        if cyclePid == 0:
          vcycle.vacutils.logLine('=============== Start cycle ===============')
          
          # Ensure /var/lib/vcycle/shared/tmp exists
          try:
            os.makedirs('/var/lib/vcycle/shared/tmp', stat.S_IRUSR|stat.S_IWUSR|stat.S_IXUSR|stat.S_IRGRP|stat.S_IXGRP)
          except:
            pass

          try:
            vcycle.shared.readConf(printConf = True, updatePipes = True)
          except Exception as e:
            print 'readConf() fails with "' + str(e) + '", skipping cycle'
          else:
            for spaceName, space in vcycle.shared.spaces.iteritems():
              vcycle.vacutils.logLine('--- Space ' + spaceName + ' ---------------------------')
              try:
                space.oneCycle()
              except Exception as e:
                print 'Processing space ' + spaceName + ' fails with exception ' + str(e)

          vcycle.vacutils.logLine('================ End cycle ================')
          sys.exit(0)

        # wait for cyclePid subprocess to finish
        os.waitpid(cyclePid, 0)

        # wait the allotted time between cycles
        time.sleep(sleepSeconds)

      sys.exit(0) # if we break out of the while loop then we exit