Runit – How to Write a Custom Stop Script for Runit

runit

I want to have a custom "stop" script runit (runsv) to execute when having to stop/restart the process. Currently it simply kills the process, then runs the "finish" script. But in my case, my process spawns dynamically child processes, so instead of simple kill, I need a "killtree" to get rid of them. How do I do that?

I know it should be done through the control options of runit but from reading the docs its not really clear to me how the stop script should be named 🙁

http://smarden.org/runit/runsv.8.html

Best Answer

From the docs

For each control character c sent to the control pipe, runsv first checks if service/control/c exists and is executable. If so, it starts service/control/c and waits for it to terminate, before interpreting the command. If the program exits with return code 0, runsv refrains from sending the service the corresponding signal. The command o is always considered as command u. On command d first service/control/t is checked, and then service/control/d. On command x first service/control/t is checked, and then service/control/x. The control of the optional log service cannot be customized.

That means you need to create a service_name/control/X, X being an executable that will run when you send the related sv command to the service, like the d command (down). If your script exits with status 0 it will not try to down the service itself.

Basically you need an executable script on /etc/sv/<service>/control/d that will do whatever you want and kill the service, clean up pids and etc.

Related Solutions

RUNIT – created first service directory, “sv start testrun” does not work

Your service isn't set up correctly. The reason it worked is that you invoked it directly from the service definition and not from the actual service control.

When runit's service management starts, it expects a /service directory to exist, although some installs (like Debian Jessie) currently have it at /etc/service for reasons unknown. The error message comes from this missing directory, which it is trying to change to, hence the unable to change service directory message. Do the following as root:

mkdir -p /etc/service
cd /
ln -s /etc/service
cd /service
ln -s /etc/sv/testrun

This will:

create the service directory if it doesn't exist
place a symlink in the root so that runsvdir will be able to change to /service as its working directory
creates a link to your testrun service, assuming you have it defined at /etc/sv/testrun

runsvdir will then be able to change its directory into /service, find your symlink for testrun, and then launch it. You can verify this by using ps fax or pstree -A to see the process tree; there should be a runsv with your command attached to it. Note: sometimes it may take a second or two for the runsvdir process to get its head oriented, so if you look right away and don't see it in the process tree, wait 2-3 seconds and try again, and it should show up. This appears to only happen when it starts up.

Using runit and monit to run / monitor services

runit is better suited for running processes, as it does not depend upon the pid files and, will also restart if the child process crashes.

Monit in turn monitors the performance of these process, and restarts them using runit as needed.

Best Answer

Related Solutions

RUNIT – created first service directory, “sv start testrun” does not work

Using runit and monit to run / monitor services

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