112 lines
2.5 KiB
Python
112 lines
2.5 KiB
Python
|
"""
|
||
|
|
Original Source:
|
||
|
|
https://web.archive.org/web/20131017130434/http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
|
||
|
|
https://web.archive.org/web/20131017130434/http://www.jejik.com/files/examples/daemon3x.py
|
||
|
|
See daemon3x.py in the uplink source tree.
|
||
|
|
|
||
|
|
More Information:
|
||
|
|
https://franklingu.github.io/programming/2016/03/01/creating-daemon-process-python-example-explanation/
|
||
|
|
https://dpbl.wordpress.com/2017/02/12/a-tutorial-on-python-daemon/
|
||
|
|
"""
|
||
|
|
|
||
|
|
import sys
|
||
|
|
import os
|
||
|
|
import time
|
||
|
|
import atexit
|
||
|
|
import signal
|
||
|
|
|
||
|
|
|
||
|
|
# TODO.md: Check why pid files are not being deleted when sending the TERM signal
|
||
|
|
class Daemon:
|
||
|
|
|
||
|
|
def __init__(self, pid_file):
|
||
|
|
self.pid_file = pid_file
|
||
|
|
|
||
|
|
def daemonize(self):
|
||
|
|
try:
|
||
|
|
pid = os.fork()
|
||
|
|
if pid > 0:
|
||
|
|
sys.exit(0)
|
||
|
|
except OSError as err:
|
||
|
|
sys.stderr.write('fork #1 failed: {0}\n'.format(err))
|
||
|
|
sys.exit(1)
|
||
|
|
|
||
|
|
os.chdir('/')
|
||
|
|
os.setsid()
|
||
|
|
os.umask(0)
|
||
|
|
|
||
|
|
try:
|
||
|
|
pid = os.fork()
|
||
|
|
if pid > 0:
|
||
|
|
sys.exit(0)
|
||
|
|
except OSError as err:
|
||
|
|
sys.stderr.write('fork #2 failed: {0}\n'.format(err))
|
||
|
|
sys.exit(1)
|
||
|
|
|
||
|
|
sys.stdout.flush()
|
||
|
|
sys.stderr.flush()
|
||
|
|
si = open(os.devnull, 'r')
|
||
|
|
so = open(os.devnull, 'a+')
|
||
|
|
se = open(os.devnull, 'a+')
|
||
|
|
|
||
|
|
os.dup2(si.fileno(), sys.stdin.fileno())
|
||
|
|
os.dup2(so.fileno(), sys.stdout.fileno())
|
||
|
|
os.dup2(se.fileno(), sys.stderr.fileno())
|
||
|
|
|
||
|
|
atexit.register(self.del_pid)
|
||
|
|
|
||
|
|
pid = str(os.getpid())
|
||
|
|
with open(self.pid_file, 'w+') as f:
|
||
|
|
f.write(pid + '\n')
|
||
|
|
|
||
|
|
def del_pid(self):
|
||
|
|
os.remove(self.pid_file)
|
||
|
|
|
||
|
|
def start(self):
|
||
|
|
try:
|
||
|
|
with open(self.pid_file, 'r') as pf:
|
||
|
|
pid = int(pf.read().strip())
|
||
|
|
except IOError:
|
||
|
|
pid = None
|
||
|
|
|
||
|
|
if pid:
|
||
|
|
message = "pid_file {0} already exist. Daemon already running?\n"
|
||
|
|
sys.stderr.write(message.format(self.pid_file))
|
||
|
|
sys.exit(1)
|
||
|
|
|
||
|
|
self.daemonize()
|
||
|
|
self.run()
|
||
|
|
|
||
|
|
def stop(self):
|
||
|
|
try:
|
||
|
|
with open(self.pid_file, 'r') as pf:
|
||
|
|
pid = int(pf.read().strip())
|
||
|
|
except IOError:
|
||
|
|
pid = None
|
||
|
|
|
||
|
|
if not pid:
|
||
|
|
message = "pid_file {0} does not exist. Daemon not running?\n"
|
||
|
|
sys.stderr.write(message.format(self.pid_file))
|
||
|
|
return
|
||
|
|
|
||
|
|
try:
|
||
|
|
while 1:
|
||
|
|
os.kill(pid, signal.SIGTERM)
|
||
|
|
time.sleep(0.1)
|
||
|
|
except OSError as err:
|
||
|
|
e = str(err.args)
|
||
|
|
if e.find("No such process") > 0:
|
||
|
|
if os.path.exists(self.pid_file):
|
||
|
|
os.remove(self.pid_file)
|
||
|
|
else:
|
||
|
|
print(str(err.args))
|
||
|
|
sys.exit(1)
|
||
|
|
|
||
|
|
def restart(self):
|
||
|
|
self.stop()
|
||
|
|
self.start()
|
||
|
|
|
||
|
|
def run(self):
|
||
|
|
"""Override this method when you subclass Daemon.
|
||
|
|
It will be called after the process has been daemonized by
|
||
|
|
start() or restart()."""
|