Auto-restart an process when it crashes

Question

I have an app that I need to autostart when the OS starts. I am running in a CentOS 6, so I am using a LSB init script placed in /etc/init.d. So far this is fine and working.

Now....besides that, what I would like is that if my app crashes (exits with error), I want that it automatically starts again. Ideally, even defining a max number of tries. In Mac's Info.plist there are the keys KeepAlive Since I already have chkconfig working, I was wondering if there is something I could do with it.

I know there is http://mmonit.com/monit/ but it may be too much for what I need.

Solution

Given you control the init.d script to start this process you might want to just wrap the execution of your process in the init.d script like so:

until myserver; do
    echo "Server 'myserver' crashed with exit code $?.  Respawning.." >&2
    sleep 1
done

This will lanch your process in an until loop basically forever, each time it dies. Counting etc. could be introduced like this:

cnt=0
max=3
until myserver; do
    let cnt=cnt+1
    echo "Server 'myserver' crashed with exit code $?.  Respawning.." >&2
    sleep 1
    [ $cnt = $max ] && exit;
done

Comments

[Bratchley]

This feature was added to systemd basically because it is such a hassle for admins to implement a third-party solution. If the application doesn't have its own monitoring process, there's nothing that supervises service continuity unless you install and configure something for that purpose.

[Rahul Patil]

what is the issue with monit ?