monitoring-nrpe

monitoring-nrpe

A simple charm that shows how to implement some monitoring with charmhelpers and nrpe to use with nagios.

Uses charmhelpers lib to work out the nrpe bits. See: https://github.com/juju/charm-helpers

Usage

charmcraft build
juju add-model examples
juju model-config default-series=focal
juju model-config logging-config="<root>=WARNING;unit=TRACE"

juju deploy nagios
juju deploy nrpe
juju deploy ./monitoring-nrpe.charm
juju relate nagios:monitors nrpe:monitors
juju relate monitoring-nrpe:local-monitors nrpe

# Visit nagios http://nagios
# Get nagiosadmin password:
juju ssh nagios/0 sudo cat /var/lib/juju/nagios.passwd

General implementation details

1. Update metadata.yaml

   provides:
     local-monitors:
     interface: local-monitors
     scope: container
   

2. Add the following to config.yaml

   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
   

3. Add custom checks (Nagios plugins) to files/nrpe-checks

   files/nrpe-checks/check_mycheck.sh
   

4. Implement the events in charm.py with something like in this charm

   def render_checks(self):
    """Render nrpe checks."""
    nrpe = NRPE()
    if not os.path.exists(self.plugins_dir):
        os.makedirs(self.plugins_dir)
   
    # register basic test
    
    nrpe.add_check(
        shortname="hellocheck",
        description="Dummy hello check",
        check_cmd="check_hello.sh",
    )
    nrpe.write()
   

5. Update charmcraft.yaml

   parts:
    charm:
    charm-python-packages: [setuptools < 58]
    prime:
      - files/*
   

6. Add to requirements.txt

   ops >= 1.3.0
   charmhelpers==0.20.24
   

Authors

Erik Lönroth, support me by attributing my work https://eriklonroth.com