vcycled

#!/usr/bin/python
#
# vcycled - VM lifecycle manager daemon for OpenStack etc
#
#  Andrew McNab, University of Manchester.
#  Copyright (c) 2013-5. 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 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:

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

        so = file('/var/log/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/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 ===============')

          try:       
            vcycle.shared.readConf()
          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.shared.cleanupMachines()
          vcycle.shared.cleanupJoboutputs() 
          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