cedadccc6f
The repo is Python 3 now, so update hacking to version 3.0 which supports Python 3. Fix problems found. Update local hacking checks for new flake8. Change-Id: I6396403d0a62f5403fc5b7fb04b6ce790c332c84
268 lines
8.5 KiB
Python
268 lines
8.5 KiB
Python
# (C) Copyright 2015-2016 Hewlett Packard Enterprise Development Company LP
|
|
# 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.
|
|
|
|
"""
|
|
***
|
|
Modified generic daemon class
|
|
***
|
|
|
|
Author: http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
|
|
www.boxedice.com
|
|
www.datadoghq.com
|
|
|
|
License: http://creativecommons.org/licenses/by-sa/3.0/
|
|
"""
|
|
|
|
# Core modules
|
|
import atexit
|
|
import errno
|
|
import logging
|
|
import os
|
|
import signal
|
|
import sys
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
class AgentSupervisor(object):
|
|
"""A simple supervisor to keep a restart a child on expected auto-restarts
|
|
"""
|
|
RESTART_EXIT_STATUS = 5
|
|
|
|
@classmethod
|
|
def start(cls, parent_func, child_func=None):
|
|
"""`parent_func` is a function that's called every time the child
|
|
process dies.
|
|
`child_func` is a function that should be run by the forked child
|
|
that will auto-restart with the RESTART_EXIT_STATUS.
|
|
"""
|
|
|
|
# Allow the child process to die on SIGTERM
|
|
signal.signal(signal.SIGTERM, cls._handle_sigterm)
|
|
|
|
while True:
|
|
try:
|
|
pid = os.fork()
|
|
if pid > 0:
|
|
# The parent waits on the child.
|
|
cls.child_pid = pid
|
|
_, status = os.waitpid(pid, 0)
|
|
if parent_func is not None:
|
|
parent_func()
|
|
else:
|
|
# The child will call our given function
|
|
if child_func is not None:
|
|
child_func()
|
|
else:
|
|
break
|
|
except OSError as e:
|
|
msg = "Agent fork failed: %d (%s)" % (e.errno, e.strerror)
|
|
logging.error(msg)
|
|
sys.stderr.write(msg + "\n")
|
|
sys.exit(1)
|
|
|
|
# Exit from the parent cleanly
|
|
if pid > 0:
|
|
sys.exit(0)
|
|
|
|
@classmethod
|
|
def _handle_sigterm(cls, signum, frame):
|
|
os.kill(cls.child_pid, signal.SIGTERM)
|
|
|
|
|
|
class Daemon(object):
|
|
"""A generic daemon class.
|
|
|
|
Usage: subclass the Daemon class and override the run() method
|
|
"""
|
|
|
|
def __init__(self, pidfile, stdin=os.devnull, stdout=os.devnull,
|
|
stderr=os.devnull, autorestart=False):
|
|
self.autorestart = autorestart
|
|
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:
|
|
msg = "fork #1 failed: %d (%s)" % (e.errno, e.strerror)
|
|
log.error(msg)
|
|
sys.stderr.write(msg + "\n")
|
|
sys.exit(1)
|
|
|
|
log.debug("Fork 1 ok")
|
|
|
|
# Decouple from parent environment
|
|
os.chdir("/")
|
|
os.setsid()
|
|
|
|
# Do second fork
|
|
try:
|
|
pid = os.fork()
|
|
if pid > 0:
|
|
# Exit from second parent
|
|
sys.exit(0)
|
|
except OSError as e:
|
|
msg = "fork #2 failed: %d (%s)" % (e.errno, e.strerror)
|
|
logging.error(msg)
|
|
sys.stderr.write(msg + "\n")
|
|
sys.exit(1)
|
|
|
|
if sys.platform != 'darwin': # This block breaks on OS X
|
|
# 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())
|
|
|
|
log.info("Daemon started")
|
|
|
|
# Write pidfile
|
|
atexit.register(self.delpid) # Make sure pid file is removed if we quit
|
|
pid = str(os.getpid())
|
|
try:
|
|
fp = open(self.pidfile, 'w+')
|
|
fp.write(str(pid))
|
|
fp.close()
|
|
os.chmod(self.pidfile, 0o644)
|
|
except Exception:
|
|
msg = "Unable to write pidfile: %s" % self.pidfile
|
|
log.exception(msg)
|
|
sys.stderr.write(msg + "\n")
|
|
sys.exit(1)
|
|
|
|
def start(self):
|
|
log.info("Starting daemon")
|
|
pid = self.pid()
|
|
|
|
if pid:
|
|
message = "pidfile %s already exists. Is it already running?\n"
|
|
log.error(message % self.pidfile)
|
|
sys.stderr.write(message % self.pidfile)
|
|
sys.exit(1)
|
|
|
|
log.info("Daemon pidfile: %s" % self.pidfile)
|
|
self.daemonize()
|
|
self.run()
|
|
|
|
def stop(self):
|
|
log.info("Stopping daemon")
|
|
pid = self.pid()
|
|
|
|
# Clear the pid file
|
|
if os.path.exists(self.pidfile):
|
|
os.remove(self.pidfile)
|
|
|
|
if pid > 1:
|
|
try:
|
|
# No supervising process present
|
|
os.kill(pid, signal.SIGTERM)
|
|
log.info("Daemon is stopped")
|
|
except OSError as err:
|
|
if str(err).find("No such process") <= 0:
|
|
log.exception("Cannot kill Agent daemon at pid %s" % pid)
|
|
sys.stderr.write(str(err) + "\n")
|
|
else:
|
|
message = "Pidfile %s does not exist. Not running?\n" % self.pidfile
|
|
log.info(message)
|
|
sys.stderr.write(message)
|
|
|
|
# A ValueError might occur if the PID file is empty but does actually exist
|
|
if os.path.exists(self.pidfile):
|
|
os.remove(self.pidfile)
|
|
|
|
return # Not an error in a restart
|
|
|
|
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().
|
|
"""
|
|
raise NotImplementedError
|
|
|
|
def info(self):
|
|
"""You should override this method when you subclass Daemon.
|
|
It will be called to provide information about the status of the process
|
|
"""
|
|
raise NotImplementedError
|
|
|
|
def status(self):
|
|
"""Get the status of the daemon. Exits with 0 if running, 1 if not.
|
|
"""
|
|
pid = self.pid()
|
|
|
|
if pid < 0:
|
|
message = '%s is not running' % self.__class__.__name__
|
|
exit_code = 1
|
|
else:
|
|
# Check for the existence of a process with the pid
|
|
try:
|
|
# os.kill(pid, 0) will raise an OSError exception if the process
|
|
# does not exist, or if access to the process is denied
|
|
# (access denied will be an EPERM error).
|
|
# If we get an OSError that isn't an EPERM error, the process
|
|
# does not exist.
|
|
# (from http://stackoverflow.com/questions/568271/
|
|
# check-if-pid-is-not-in-use-in-python,
|
|
# Giampaolo's answer)
|
|
os.kill(pid, 0)
|
|
except OSError as e:
|
|
if e.errno != errno.EPERM:
|
|
message = \
|
|
'%s pidfile contains pid %s, but no running process could be found' % (
|
|
self.__class__.__name__, pid)
|
|
exit_code = 1
|
|
else:
|
|
message = '%s is running with pid %s' % (self.__class__.__name__, pid)
|
|
exit_code = 0
|
|
|
|
log.info(message)
|
|
sys.stdout.write(message + "\n")
|
|
sys.exit(exit_code)
|
|
|
|
def pid(self):
|
|
# Get the pid from the pidfile
|
|
try:
|
|
pf = open(self.pidfile, 'r')
|
|
pid = int(pf.read().strip())
|
|
pf.close()
|
|
return pid
|
|
except IOError:
|
|
return None
|
|
except ValueError:
|
|
return None
|
|
|
|
def delpid(self):
|
|
try:
|
|
os.remove(self.pidfile)
|
|
except OSError:
|
|
pass
|