This is a Moodle plugin to simplify monitoring the Moodle service (as opposed to the hardware and infrastructure) using Nagios. It provides:

1. A simple API which allows plugins to implement "services" which can be monitored.
2. A Nagios plugin script (/cli/check_moodle) which communicates with the Moodle plugin to get service status into Nagios.
3. A couple of simple example services.

Note that this plugin is intended for experienced systems administrators who are familiar with both Moodle and Nagios configuration!

NB: this is currently in development and should not be used on live systems!

The Moodle plugin should be installed as normal.

The Nagios plugin requires a PHP executable to be available on the server.

(All paths given are the default locations for a Ubuntu install of nagios3 using apt-get)

Copy / move / symlink the Nagios plugin (/cli/check_moodle) to your Nagios plugins directory (/usr/lib/nagios/plugins). Change the permissions on the script to make it executable. Edit the $MOODLE_DIR and (if necessary) the PHP location in the shebang line to reflect your environment.

1. Create a new file, moodle.cfg, in your Nagios plugins configuration directory (/etc/nagios-plugins/config).
2. Add a command definition for each Moodle service to be monitored, e.g.:

define command{
        command_name    check_moodle_cron
        command_line    /usr/lib/nagios/plugins/check_moodle -p=local_nagios -s=cron
        }

Note the use of Moodle-style parameter passing (using =). Use these command in Nagios service definitions as normal.

1. The Nagios plugin calls the script /cli/check.php in the Moodle plugin. This means that the user account Nagios is running under must have write access to the Moodle data directory, otherwise all checks will result in an error message.
2. If the user account Nagios is running under has to use sudo to call the PHP executable, this must be configured in the shebang line in the check_moodle script. The sudo access for the account must also be configured to be able to run the PHP executable without being challenged for a password.

The local_nagios plugin scans other Moodle plugins looking for a db/local_nagios.php file.

This should contain a single definition for a variable named "$services", which is an associative array of service name to definition. The definition is a key value pair containing at least the "classname", and optionally "params". See the plugin's db/local_nagios.php file for examples.

The service class must extend the local_nagios\service class and implement the check_status() method.

The \local_nagios\service object has constants for the status code, e.g. \local_nagios\service::NAGIOS_STATUS_WARNING

There is a simple admin page for the plugin available through Plugins -> Local plugins -> Nagios monitoring.

This simply displays the available services in order for administrators to configure Nagios to check them.

1. The above describes how the Nagios plugin should be set up for an environment where Nagios and Moodle are running on the same server. This is unlikely to be the case for most installations, where the two systems may be on different servers. In this case, the Nagios NRPE system should be used.
2. The Nagios plugin is intended to be run on a Linux platform, although it may be possible to get it to work under Windows.