Supervisor

This page attempts to answer these questions.

Will Supervisor help me? http://supervisord.org

Q1. How do I set up a Python script so that I can easily start and stop it and monitor whether it's crashed?

Q2. Can I start multiple instances of the same script each with a different configuration?

Installing "Supervisor" AKA "Supervisord"

% sudo apt-get install supervisor

If you want the latest version next do

% sudo apt-get remove supervisor
% sudo easy_install supervisor

This trick will cause the Debian/Ubuntu startup files to be left around which you can then edit. Like /etc/init.d/supervisor I added a user and group for "supervisor".

Configuring Supervisor

sudo mkdir /etc/supervisor echo_supervisord_conf | sudo tee /etc/supervisor/supervisord.conf

/etc/defaults/supervisor: DAEMON_OPTS="-c /etc/supervisor/supervisord.conf"

sudo mkdir /var/run/supervisor sudo chown supervisor /var/run/supervisor

Things I changed in config file

1. Change location of logfile to /var/log/supervisord.log
2. Change pidfile to /var/run/supervisor/supervisord.pid
3. Enable inet_http_server section with for example, port=*.9001
4. Set user to 'supervisor'
5. Enable reading files from /etc/supervisor/conf.d/ (see 'include')

Do nothing test script

Here is a script that will log to the system log, and sleep for 10 minutes. It handles control-C exit. It optionally accepts an arg that can be anything and writes it to the log. This is to simulate running multiple instances with different configurations.

#/usr/bin/python
import time, logging, logging.handlers
instance = 'default'
try:
  instance = sys.argv[1]
except:
  pass
logging.basicConfig(level=logging.INFO)
log = logging.getLogger(__name__)
handler = logging.handlers.SysLogHandler(address='/dev/log')
log.addHandler(handler)
log.info("Start doing nothing.")
forever = True
try:
   while forever:
      log.info("MARK " + instance)
      time.sleep(60 * 10) 
except KeyboardInterrupt:
   log.info("Interrupt detected.")
log.info("Completed successfully.")
exit(0)