When refactoring a check_memory I wrote a few years ago I bumped into the feared

NRPE: Unable to read output

error message on our nagios instance.

When looking for a solution I went through most possible debug steps I could think of and which are nicely described by nagios support but didn't found any solution.

I almost grabbed to some anti depressants when I thought of the thing I always forget about.

SELINUX

When crawling through the audit log it became clear I forgot to configure the proper selinux context type for the new script.

type=PATH msg=audit(1518702310 …

Recently I started to try writing a customized script for the icinga monitoring tool. I will try to describe the steps I went trough to achieve this in this post. I assume you already have a working icinga setup. If not you can find documentation about this on http://docs.icinga.org/.

First of all you need to script. I created a script which will check if a service is running using the command

# /etc/init.d/service status

to see how to implement this in icinga. The script can be found on my github repo.

Once you have tested …