184 lines
5.2 KiB
Python
184 lines
5.2 KiB
Python
#!/usr/bin/env python
|
|
"""Generic deamon."""
|
|
# (c) Copyright 2016 Hewlett-Packard Development Company, L.P.
|
|
#
|
|
# Licensed under the Apache License, Version 2.0 (the "License");
|
|
# you may not use this file except in compliance with the License.
|
|
# You may obtain a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS,
|
|
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
# See the License for the specific language governing permissions and
|
|
# limitations under the License.
|
|
|
|
from __future__ import print_function
|
|
|
|
import atexit
|
|
import logging as log
|
|
import os
|
|
import sys
|
|
import time
|
|
|
|
from signal import SIGTERM
|
|
|
|
|
|
class Daemon(object):
|
|
|
|
"""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'):
|
|
"""Instantiantion."""
|
|
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 as e:
|
|
sys.stderr.write("fork #1 failed: %d (%s)\n" %
|
|
(e.errno, e.strerror))
|
|
log.error(e)
|
|
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 as e:
|
|
sys.stderr.write("fork #2 failed: %d (%s)\n"
|
|
% (e.errno, e.strerror))
|
|
log.error(e)
|
|
sys.exit(1)
|
|
|
|
# redirect standard file descriptors
|
|
sys.stdout.flush()
|
|
sys.stderr.flush()
|
|
si = open(self.stdin, 'r')
|
|
so = open(self.stdout, 'a+')
|
|
se = open(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())
|
|
f = open(self.pidfile, 'w+')
|
|
f.write("%s\n" % pid)
|
|
f.close()
|
|
|
|
def delpid(self):
|
|
"""Delete PID file."""
|
|
os.remove(self.pidfile)
|
|
|
|
def start(self):
|
|
"""Start the daemon."""
|
|
log.error("Test")
|
|
# Check for a pidfile to see if the daemon already runs
|
|
try:
|
|
pf = open(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()
|
|
|
|
# @todo needs some enhancement like check /proc/%pid/status if it's
|
|
# really running or not ! may be it's killed by external process
|
|
# the PID won't be updated !
|
|
def status(self):
|
|
"""Check daemon status."""
|
|
try:
|
|
pf = open(self.pidfile, 'r')
|
|
pid = int(pf.read().strip())
|
|
pf.close()
|
|
except IOError:
|
|
pid = None
|
|
|
|
if pid:
|
|
message = "pidfile %s already exist. Daemon already " \
|
|
"running. PID: %d \n"
|
|
sys.stdout.write(message % (self.pidfile, pid))
|
|
sys.exit(0)
|
|
else:
|
|
message = "Service not running!\n"
|
|
sys.stdout.write(message)
|
|
sys.exit(0)
|
|
|
|
def stop(self):
|
|
"""Stop the daemon."""
|
|
# Get the pid from the pidfile
|
|
try:
|
|
pf = open(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 as 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().
|
|
"""
|