juju-installer

A lightweight Debian package that enables a one-command Juju experience on Ubuntu.

Instead of manually installing snaps, initializing substrates, bootstrapping controllers, and creating models, users can simply run:

juju deploy postgresql              # LXD substrate
juju deploy postgresql-k8s --trust  # Canonical K8s substrate

On a fresh Ubuntu 24.04+ system, juju-installer handles everything automatically: installing the required snaps, initializing the substrate (LXD or Canonical K8s), bootstrapping a Juju controller, creating a model, and executing the deploy.

How It Works

juju-installer follows the same pattern as Ubuntu's lxd-installer package:

1. A thin wrapper script at /sbin/juju intercepts juju commands
2. If the Juju snap is not installed, it detects the target substrate from the charm name (-k8s suffix → Canonical K8s, otherwise → LXD)
3. It triggers the appropriate systemd socket-activated service (no sudo required): snap-only, LXD, or K8s
4. For juju deploy commands, the wrapper also bootstraps the Juju controller as the calling user
5. Once setup is complete, the wrapper passes through to the real /snap/bin/juju with zero overhead

Privilege Split

• Root operations (via systemd socket): snap install juju, snap install lxd, lxd init --auto, snap install k8s, k8s bootstrap, k8s enable local-storage
• User operations (in the wrapper): juju bootstrap, juju add-k8s, juju add-model welcome

No user-controlled data crosses the privilege boundary. The socket is a trigger, not a command channel.

Requirements

• Ubuntu 24.04 (Noble) or later
• lxd-installer package (pulled in as a dependency)
• User must be a member of the lxd system group

Installation

From PPA (recommended)

sudo add-apt-repository ppa:taurus/juju-installer
sudo apt update
sudo apt install juju-installer

From .deb (local build)

sudo apt install ./juju-installer_*.deb

From source

dpkg-buildpackage -us -uc
sudo apt install ../juju-installer_*.deb

Usage

# Deploy a VM charm (triggers LXD setup on first run)
juju deploy postgresql

# Deploy a K8s charm (triggers Canonical K8s setup on first run)
juju deploy postgresql-k8s --trust

# Run any juju command (triggers snap install only)
juju version
juju help

Package Contents

/sbin/juju                                                  # wrapper script
/usr/lib/systemd/system/juju-installer-snap.socket          # snap-only socket
/usr/lib/systemd/system/juju-installer-snap@.service        # snap-only service
/usr/lib/systemd/system/juju-installer-lxd.socket           # LXD socket
/usr/lib/systemd/system/juju-installer-lxd@.service         # LXD service
/usr/lib/systemd/system/juju-installer-k8s.socket           # K8s socket
/usr/lib/systemd/system/juju-installer-k8s@.service         # K8s service
/usr/share/juju-installer/juju-installer-snap-service       # snap install logic
/usr/share/juju-installer/juju-installer-lxd-service        # LXD install/init logic
/usr/share/juju-installer/juju-installer-k8s-service        # K8s install/bootstrap logic

Design

See docs/specs/2026-05-11-juju-installer-design.md for the PoC1 (LXD support) design and docs/specs/2026-05-12-poc2-k8s-support-design.md for the PoC2 (K8s support) design.

Future Work

• Dedicated juju system group (instead of reusing lxd)
• Charmhub API detection (query charm metadata instead of name suffix)
• Re-bootstrap after snap already installed
• Configurable snap channels
• CI/CD via GitHub Actions

Contributing

This project is part of Canonical. Contributions are welcome via pull requests.

License

Copyright 2026 Canonical Ltd.

Licensed under the Apache License, Version 2.0. See LICENSE for details.