NRPE interface for Juju Operator Framework charms

This interface works with the NRPE charm to provide monitoring and altering in combination with Nagios

To use it, add the library to your requirements.txt so charmcraft can embed it into your final charm:

ops
-e git://github.com/canonical/ops-lib-nrpe.git#egg=ops-lib-nrpe

Declare the use of the relation in the provides section of you charm's metadata.yaml file:

provides:
  nrpe-external-master:
    interface: nrpe-external-master
    scope: container

NRPE must be deployed on the same machine as the unit it observes, make sure to specify scope: container as part of the relation definition.

Add the following configuration options to your charm's config.yaml file:

  nagios_context:
    default: "juju"
    type: string
    description: |
      Used by the nrpe subordinate charms.
      A string that will be prepended to instance name to set the host name
      in nagios. So for instance the hostname would be something like:
        juju-myservice-0
      If you're running multiple environments with the same services in them
      this allows you to differentiate between them.
  nagios_servicegroups:
    default: ""
    type: string
    description: |
      A comma-separated list of nagios servicegroups.
      If left empty, the nagios_context will be used as the servicegroup

Usage

from nrpe.client import NRPEClient

class MyCharm(ops.charm.CharmBase):
    _state = ops.framework.StoredState()

    def __init__(self, *args):
        super().__init__(*args)
        self.nrpe_client = NRPEClient(self, 'nrpe-external-master')
        self.framework.observe(self.nrpe_client.on.nrpe_available, self.on_nrpe_available)

    def on_nrpe_available(self, event):
        check_name = "check_{}".format(self.model.unit.name.replace("/", "_"))

        self.nrpe_client.add_check(command=[
            '/usr/lib/nagios/plugins/check_tcp',
            '-H', '127.0.0.1'
            '-p', '8080'
        ], name=check_name)

        # Save all new checks to filesystem and to Nagios
        self.nrpe_client.commit()