Removing a plugin

In this recipe, we'll remove a plugin that we no longer need as part of our Nagios Core installation. Perhaps it's not working correctly, the service it monitors is no longer available, or there are security or licensing concerns with its usage.

Getting ready

You should have a Nagios Core 4.0 or newer server running with a few hosts and services configured already, and you should have a plugin that you would like to remove from the server. In this instance, we'll remove the no longer needed check_rsync plugin from our Nagios Core server.

How to do it...

We can remove a plugin from our Nagios Core instance as follows:

1. Remove any part of the configuration that uses the plugin, including hosts or services that use it for a check_command and command definitions that refer to the program. As an example, the following definition for a command would no longer work after we removed the check_rsync plugin:

   define command {
       command_name  check_rsync
       command_line  $USER1$/check_rsync -H $HOSTADDRESS$
   }

   Using a tool such as grep(1) can be a good way to find mentions of the command and plugin:

   # grep -R check_rsync /usr/local/nagios/etc
   

2. Change the directory location on the Nagios Core server to wherever the plugins are kept. The default location is /usr/local/nagios/libexec:

   # cd /usr/local/nagios/libexec
   

3. Delete the plugin using rm(1):

   # rm check_rsync
   

4. Validate the configuration and restart the Nagios Core server:

   # /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
   # /etc/init.d/nagios reload
   

How it works...

Nagios Core plugins are simply external programs that the server uses to perform checks of hosts and services. If a plugin is no longer wanted, all that we need to do is remove references to it in our configuration, if any, and delete it from /usr/local/nagios/libexec.

There's more...

There's not usually any harm in leaving the plugin's program on the server even if Nagios Core isn't using it. It doesn't slow anything down or cause any other problems, and it may be needed later. Nagios Core plugins are generally quite small programs and should not really cause disk space concerns on a modern server.

See also

• The Finding a plugin section in this chapter
• The Installing a plugin section in this chapter
• The Creating a new command section in this chapter