Charm development utils

A repository to collect initiatives around making the life of a charm author easier.

Table of Contents

• Charm development utils
  • cloud-init
  • How to launch a VM using cloud-init script
    • Using Multipass
    • Using LXD
  • zsh_themes

cloud-init

In the cloud-init directory you will find the following cloud-init scripts to launch reusable VMs to everyday charm development:

• charm-dev-juju-4.0.yaml
• charm-dev-juju-3.6.yaml

These script will create a VM with:

• juju (stable 4.0 and 3.6)
• Canonical Kubernetes 1.35-classic/stable
• ZSH as a default SHELL with oh-my-zsh and juju theme with plugins:
  • autosuggestions
  • syntax highlighting
  • juju
• Pietro's amazing jhack tool.
• just
• goss + kgoss

How to launch a VM using cloud-init script

Using Multipass

Let's say you need to launch a VM using Multipass that runs juju 3.6/stable with:

• 4G RAM
• 3 CPUs
• 30G disk
• and mounting your repos directory inside the ubuntu user home directory
• an IP address provide

you may run:

multipass launch --cloud-init charm-dev-juju-3.6.yaml \
--timeout 1200 \
--name charm-dev-36 \
--memory 4G \
--cpus 3 \
--disk 30G \
--mount /home/jose/trabajos/canonical/repos:/home/ubuntu/repos \
--network enp1s0

Once the VM is ready you will see:

Launched: charm-dev-36
Mounted '/home/jose/trabajos/canonical/repos' into 'charm-dev-36:/home/ubuntu/repos'

Now you can jump into the new VM:

multipass shell charm-dev-36

Welcome to Ubuntu 24.04.1 LTS (GNU/Linux 6.8.0-51-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/pro


Expanded Security Maintenance for Applications is not enabled.

0 updates can be applied immediately.

Enable ESM Apps to receive additional future security updates.
See https://ubuntu.com/esm or run: sudo pro status


Last login: Thu Jan  9 09:49:25 2025 from 10.169.97.1
╭─ubuntu@charm-dev-36 ~ [lxd:null]
╰─$

And voilà, you have a VM with all you need to start developing Charmed Operators!

Using LXD

Let's say you need to launch a VM using LXD that runs juju 3.6/stable with:

• 4G RAM
• 3 CPUs
• 30G disk
• and mounting your repos directory inside the ubuntu user home directory
• an IP provided by the DHCP present in the host network

you need to run:

lxc init ubuntu:24.04 charm-dev-36 --vm \
  -c limits.memory=4GB \
  -c limits.cpu=3 \
  -c cloud-init.user-data="$(cat charm-dev-juju-3.6.yaml)" \
  -c environment.LXC_START_COMMAND="/bin/zsh --login -c 'su - ubuntu'" \
  -s default

lxc config device set charm-dev-36 root size=30GB

lxc config device add charm-dev-36 repos disk \
  source=/home/jose/trabajos/canonical/repos \
  path=/home/ubuntu/repos

lxc config device add charm-dev-36 eth0 nic \
  nictype=bridged \
  parent=br-enp1s0

lxc start charm-dev-36

Now you can jump into the new VM:

lxc exec charm-dev-36 -- su ubuntu

╭─ubuntu@charm-dev-36 /root [lxd:null]
╰─$

And voilà, you have a VM with all you need to start developing Charmed Operators!

zsh_themes

In the zsh_themes directory you will find a juju.zsh-theme that uses the juju plugin to show a prompt with juju information about controller and model.