Installing Supervisor¹ and Superlance² on CentOS/RHEL/Fedora can be a little tricky, as the versions of those packages included in the main repositories are too old to be useful. In this tutorial, I will show you how to make a stock install of the latest versions on CentOS, and will omit the configuration of Supervisor itself as that will be specific to your applications.

Installing Supervisor

As the super user, firstly install the Python setup tools to gain EasyInstall³, then use that to install Supervisor:

$ yum install python-setuptools
$ easy_install supervisor

You should now have the latest version installed:

$ supervisord --version
3.1.0

Create a config file

Easy Install will not create a config file for Supervisor for you, but luckily Supervisor includes a utility called echo_supervisord_conf to generate a default configi file for you:

$ echo_supervisord_conf > /etc/supervisord.conf

You can now make changes directly to the new /etc/supervisord.conf file.

Running the service

While it is possible to start Supervisor using the supervisord command, I like to run services via an init script. Here is an example I use (placed in /etc/rc.d/init.d/supervisord):

#!/bin/bash
 
. /etc/init.d/functions
 
DAEMON=/usr/bin/supervisord
PIDFILE=/var/run/supervisord.pid
 
[ -x "$DAEMON" ] || exit 0
 
start() {
        echo -n "Starting supervisord: "
        if [ -f $PIDFILE ]; then
                PID=`cat $PIDFILE`
                echo supervisord already running: $PID
                exit 2;
        else
                daemon  $DAEMON --pidfile=$PIDFILE -c /etc/supervisord.conf
                RETVAL=$?
                echo
                [ $RETVAL -eq 0 ] && touch /var/lock/subsys/supervisord
                return $RETVAL
        fi
 
}
 
stop() {
        echo -n "Shutting down supervisord: "
        echo
        killproc -p $PIDFILE supervisord
        echo
        rm -f /var/lock/subsys/supervisord
        return 0
}
 
case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    status)
        status supervisord
        ;;
    restart)
        stop
        start
        ;;
    *)
        echo "Usage:  {start|stop|status|restart}"
        exit 1
        ;;
esac
exit $?

You will need to create that file, containing the above script, and make sure it's executable:

$ nano /etc/rc.d/init.d/supervisord
$ chmod 755 /etc/rc.d/init.d/supervisord

You will now have access to the following commands to control Supervisor:

$ service supervisord start
$ service supervisord stop
$ service supervisord status
$ service supervisord restart

Superlance

Superlance is a set of additional plugins for Supervisor, that includes plugins for sending email or SMS alerts when a Supervisor process exists unexpectedly, for monitoring memory usage of Supervisor processes, and a few other useful monitoring and alerting utilities. You can also install it via EasyInstall:

$ easy_install superlance

References