Hallo,
I'm trying to let a python script run as service (daemon) on (ubuntu) linux.
On the web there exist several solutions like:
http://pypi.python.org/pypi/python-daemon/
A well-behaved Unix daemon process is tricky to get right, but the required steps are much the same for every daemon program. A DaemonContext instance holds the behaviour and configured process environment for the program; use the instance as a context manager to enter a daemon state.
http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
However as I want to integrate my python script specifically with ubuntu linux my solution is a combination with an init.d script
#!/bin/bash
WORK_DIR="/var/lib/foo"
DAEMON="/usr/bin/python"
ARGS="/opt/foo/linux_service.py"
PIDFILE="/var/run/foo.pid"
USER="foo"
case "$1" in
start)
echo "Starting server"
mkdir -p "$WORK_DIR"
/sbin/start-stop-daemon --start --pidfile $PIDFILE \
--user $USER --group $USER \
-b --make-pidfile \
--chuid $USER \
--exec $DAEMON $ARGS
;;
stop)
echo "Stopping server"
/sbin/start-stop-daemon --stop --pidfile $PIDFILE --verbose
;;
*)
echo "Usage: /etc/init.d/$USER {start|stop}"
exit 1
;;
esac
exit 0
and in python:
import signal
import time
import multiprocessing
stop_event = multiprocessing.Event()
def stop(signum, frame):
stop_event.set()
signal.signal(signal.SIGTERM, stop)
if __name__ == '__main__':
while not stop_event.is_set():
time.sleep(3)
My question now is if this approach is correct. Do I have to handle any additional signals? Will it be a "well-behaved Unix daemon process"?
Assuming your daemon has some way of continually running (some event loop, twisted, whatever), you can try to use upstart
.
Here's an example upstart config for a hypothetical Python service:
description "My service"
author "Some Dude <[email protected]>"
start on runlevel [234]
stop on runlevel [0156]
chdir /some/dir
exec /some/dir/script.py
respawn
If you save this as script.conf to /etc/init
you simple do a one-time
$ sudo initctl reload-configuration
$ sudo start script
You can stop it with stop script
. What the above upstart conf says is to start this service on reboots and also restart it if it dies.
As for signal handling - your process should naturally respond to SIGTERM
. By default this should be handled unless you've specifically installed your own signal handler.