This one was a real facepalm moment, but I thought I’d share in case anyone else runs into the same thing.
I’ve been working on migrating from Nagios to Icinga2. One of the services I monitor is whether or not a given host has any available yum updates. This service, which I label
check_yum, worked on all my hosts except for the Icinga2 host. All the other services monitored on that host were working, but
check_yum returned an error:
NRPE: Unable to read output
I tried running the test manually on the Icinga2 host:
/usr/lib64/nagios/plugins/check_nrpe -H localhost -c check_yum NRPE: Unable to read output
I checked to make sure NRPE was listening, in this case via
I checked the service definition to see what script/plugin NRPE runs:
cat /etc/nrpe.d/check_yum.cfg command[check_yum]=/usr/lib64/nagios/plugins/check_updates -w 0 -c 10 -t 60
I tried to run that manually and…the file
/usr/lib64/nagios/plugins/check_updates did not exist.
I installed the corresponding
sudo yum install nagios-plugins-check-updates
Now it works! It was a reminder to myself to check the basics before trying to troubleshoot network issues.