nrpe-external-master interface

Use this interface to register nagios checks in your charm layers.

Purpose

This interface is designed to interoperate with the nrpe-external-master subordinate charm.

How to use in your layers

The event handler for nrpe-external-master.available is called with an object through which you can register your own custom nagios checks, when a relation is established with nrpe-external-master:nrpe-external-master.

This object provides a method,

add_check(args, name=check_name, description=description, context=context, unit=unit)

which is called to register a nagios plugin check for your service.

All arguments are required.

args is a list of nagios plugin command line arguments, starting with the path to the plugin executable.

name is the name of the check registered in nagios

description is some text that describes what the check is for and what it does

context is the nagios context name, something that identifies your application

unit is hookenv.local_unit()

The nrpe subordinate installs check_http, so you can use it like this:

@when('nrpe-external-master.available')
def setup_nagios(nagios):
    config = hookenv.config()
    unit_name = hookenv.local_unit()
    nagios.add_check(['/usr/lib/nagios/plugins/check_http',
            '-I', '127.0.0.1', '-p', str(config['port']),
            '-e', " 200 OK", '-u', '/publickey'],
        name="check_http",
        description="Verify my awesome service is responding",
        context=config["nagios_context"],
        unit=unit_name,
    )

If your nagios.add_check defines a custom plugin, you will also need to restart the nagios-nrpe-server service.

Consult the nagios documentation for more information on how to write your own plugins or find one that does what you need.

Example deployment

$ juju deploy your-awesome-charm
$ juju deploy nrpe-external-master --config site-nagios.yaml
$ juju add-relation your-awesome-charm nrpe-external-master

where site-nagios.yaml has the necessary configuration settings for the subordinate to connect to nagios.