Missing Nagios plugins in CentOS 7

I set up a Nagios server on a CentOS 7 VM (Virtual Machine):

sudo yum install epel-release sudo yum install nrpe sudo yum install nagios

By default it sets up some basic checks for localhost. When I checked the Nagios site at http://127.0.0.1/nagios/, I found that even PING was critical:

(No output on stdout) stderr: execvp(/usr/lib64/nagios/plugins/check_ping, ...) failed. errno is 2: No such file or directory

I checked the contents of the plugins directory:

# ls /usr/lib64/nagios/plugins eventhandlers negate urlize utils.sh

Sure enough, the usual suspects are not there. E.g.:

check_load
check_ping
check_disk
check_http
check_procs

Eventually I stumbled onto the following document, /usr/share/doc/nagios-plugins-2.0.3/README.Fedora:

Fedora users

Nagios plugins for Fedora have all been packaged separately. For
example, to isntall the check_http just install nagios-plugins-http.

All plugins are installed in the architecture dependent directory
/usr/lib{,64}/nagios/plugins/.

I installed some of the plugins following that convention:

sudo yum install nagios-plugins-load sudo yum install nagios-plugins-ping sudo yum install nagios-plugins-disk sudo yum install nagios-plugins-http sudo yum install nagios-plugins-procs

Now the the corresponding plugins exist in /usr/lib64/nagios/plugins, and Nagios reports OK for those checks on localhost.

3 thoughts on “Missing Nagios plugins in CentOS 7”

Rien says:

2 May 2017 at 11:44 am

Thanks a heap! Exactly what I needed.
Noah Birnel says:

24 Jul 2018 at 5:51 pm

nagios-plugins-all is available in epel.
Chris Herdt says:

27 Jul 2018 at 12:01 pm
Thanks to Noah Birnel for pointing out nagios-plugins-all! While I was looking at the various yum packages for Nagios, NRPE, and plugins I also noted this one:
```
nagios-plugins
```
What is nagios-plugins and how is it different than nagios-plugins-all?
```
$ yum info nagios-plugins
...
Summary     : Host/service/network monitoring program plugins for Nagios
...
```
```
$ yum info nagios-plugins-all
...
Summary     : Nagios Plugins - All plugins
...
```
It’s still not really clear what the nagios-plugins package provides.

Before any Nagios plugins are installed, the plugins directory already exists:
```
/usr/lib64/nagios/plugins
```
It contains just an empty directory, eventhandlers.

After installing nagios-plugins (no dependent packages):
```
$ ls -l
total 100
drwxr-xr-x. 2 root root     6 Nov 20  2017 eventhandlers
-rwxr-xr-x. 1 root root 45328 Nov 21  2017 negate
-rwxr-xr-x. 1 root root 45104 Nov 21  2017 urlize
-rwxr-xr-x. 1 root root  2791 Nov 21  2017 utils.sh
```
It looks like these are used by Nagios and plugins. urlize, for example, turns plugin output into a clickable link. I don’t understand why negate exists: given a Nagios plugin and options, it returns the opposite of what the plugin returns. CRITICAL instead of OK. Why does this even exist?

After installing nagios-plugins-all (along with 103 dependent packages):
```
$ ls | wc -l
67
```
The 3 files installed by nagios-plugins are also present, as it was one of the dependencies.

Even installing just nagios-plugins-ping includes nagios-plugins as a dependency, so it looks like the files included in that package (negate, urlize, and utils.sh) are required by most (if not all) of the nagios-plugins-* packages.

In general, I recommend avoiding installing any packages that aren’t strictly necessary. I would avoid installing nagios-plugins-all, but it is admittedly convenient.

3 thoughts on “Missing Nagios plugins in CentOS 7”

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