Juju Charms tutorial

Software installation

Installation of juju and charmcraft:

Creation of the Charm structure

After running these commands, you should have the following structure:

Changing files

Changing files to create a basic charm


You should replace the maintainer:





Keep in mind that you should replace the hostname with your machine, as well as the username and password that you have.


Before building the charm you might need to execute the following commands:

$ lxd init --auto
$ lxc network set lxdbr0 ipv6.address none

Build the charm:

$ charmcraft build

Before deploying you might need to choose your controller (In your case should be localhost):

$ juju bootstrap

Deploying the charm using the configurations in the local-config file:

$ juju deploy ./prometheus-node-exporter_ubuntu-20.04-amd64.charm --config local-config.yaml

Check status:

$ juju status

Execute the ‘run‘ action to run a command inside the VM/VNF. You can check your unit_id with juju status.

$ juju run-action prometheus-node-exporter/<unit_id> run "command"="ls -la" --wait

Adding the Prometheus Node Metrics Exporter’s logic

Update actions.yaml

Update src/charm.py

Add needed imports

Inside the SampleProxyCharm class add the custom actions

Define the 2 functions inside the class:

Add functions to handle the prometheus:

Check if charm is working.

Build and deploy the charm again.

First, remove the first charm that we deployed:

$ juju remove-application prometheus-node-exporter

Using the commands in the first charm, build and deploy.

Run the action for the prometheus that we created:

$ juju run-action prometheus-node-exporter/<unit_id> start-prometheus-exporter --wait

Useful juju commands

Delete an application

$ juju remove-application <application_id>

Delete a machine

$ juju remove-machine <machine_id>

Check deployment logs

$ juju debug-log

Continuously observe deployment status

$ juju status –watch 5s

Access machine terminal

$ juju ssh <machine_id>

Tutorial materials

For a better description of the tutorial, you can check our video here.

You can also check a PDF version of this tutorial here.