Daemon basado en Python

Bueno raza, aqui les traigo una simple clase de daemon que pueden utilizar para hacer sus propios daemons facilmente. Esta basado en el de este camarada, yo solo le agregue la integracion con signals para que cuando se mate el servicio de la forma kill pid hiciera el proceso normal de limpieza y removiera el archivo pid. A continuacion la clase:

 

#!/usr/bin/env python

import sys, os, time, atexit
from signal import SIGTERM 

class Daemon:
	"""
	A generic daemon class.
	
	Usage: subclass the Daemon class and override the run() method
	"""
	def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
		self.stdin = stdin
		self.stdout = stdout
		self.stderr = stderr
		self.pidfile = pidfile
	
	def daemonize(self):
		"""
		do the UNIX double-fork magic, see Stevens' "Advanced 
		Programming in the UNIX Environment" for details (ISBN 0201563177)
		http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
		"""
		try: 
			pid = os.fork() 
			if pid > 0:
				# exit first parent
				sys.exit(0) 
		except OSError, e: 
			sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
			sys.exit(1)
	
		# decouple from parent environment
		os.chdir("/") 
		os.setsid() 
		os.umask(0) 
	
		# do second fork
		try: 
			pid = os.fork() 
			if pid > 0:
				# exit from second parent
				sys.exit(0) 
		except OSError, e: 
			sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
			sys.exit(1) 
	
		# redirect standard file descriptors
		sys.stdout.flush()
		sys.stderr.flush()
		si = file(self.stdin, 'r')
		so = file(self.stdout, 'a+')
		se = file(self.stderr, 'a+', 0)
		os.dup2(si.fileno(), sys.stdin.fileno())
		os.dup2(so.fileno(), sys.stdout.fileno())
		os.dup2(se.fileno(), sys.stderr.fileno())
	
		# write pidfile
		atexit.register(self.delpid)
		pid = str(os.getpid())
		file(self.pidfile,'w+').write("%s\n" % pid)
	
	def delpid(self):
		os.remove(self.pidfile)

	def start(self):
		"""
		Start the daemon
		"""
		# Check for a pidfile to see if the daemon already runs
		try:
			pf = file(self.pidfile,'r')
			pid = int(pf.read().strip())
			pf.close()
		except IOError:
			pid = None
	
		if pid:
			message = "pidfile %s already exist. Daemon already running?\n"
			sys.stderr.write(message % self.pidfile)
			sys.exit(1)
		
		# Start the daemon
		self.daemonize()
		self.run()

	def stop(self, signum=None, frame=None):
		"""
		Stop the daemon
		"""
		# Get the pid from the pidfile
		try:
			pf = file(self.pidfile,'r')
			pid = int(pf.read().strip())
			pf.close()
		except IOError:
			pid = None
	
		if not pid:
			message = "pidfile %s does not exist. Daemon not running?\n"
			sys.stderr.write(message % self.pidfile)
			return # not an error in a restart

		# Try killing the daemon process	
		try:
			while 1:
				os.kill(pid, SIGTERM)
				time.sleep(0.1)
		except OSError, err:
			err = str(err)
			if err.find("No such process") > 0:
				if os.path.exists(self.pidfile):
					os.remove(self.pidfile)
			else:
				print str(err)
				sys.exit(1)

	def restart(self):
		"""
		Restart the daemon
		"""
		self.stop()
		self.start()
		
		

	def run(self):
		"""
		You should override this method when you subclass Daemon. It will be called after the   process has been
		daemonized by start() or restart().
		"""

Con esto solo tienen que crear su servicio anulando el metodo run y agregando el modulo signals para atrapar SIGTERM:

 #!/usr/bin/env python

import sys, time, signal, os
from daemon import Daemon
	
	
class MyDaemon(Daemon):

	def run(self):
               
		signal.signal(signal.SIGTERM, self.stop)

		while True:
			
			print 'A la verga todo'

			time.sleep(1)

  

if __name__ == "__main__":

	daemon = MyDaemon('/tmp/daemon.pid')

	if len(sys.argv) == 2:

		if 'start' == sys.argv[1]:

			daemon.start()

		elif 'stop' == sys.argv[1]:

			daemon.stop()

		elif 'restart' == sys.argv[1]:

			daemon.restart()

		else:

			print "Unknown command"

			sys.exit(2)

		sys.exit(0)

	else:

		print "usage: %s start|stop|restart" % sys.argv[0]

		sys.exit(2)

LO MAS VISITADO