Charm delivery

Overview

Juju charms are delivered via the online Charmhub. This page provides charm delivery information in the context of the OpenStack Charms project.

There are two general types of OpenStack charms: one that does use channels and one that does not (legacy) - see the Charm types for details. This page will focus on channel charms.

Channels

The notion of channels is central to the delivery of the correct OpenStack charm.

By definition, a channel is comprised of three components: track, risk level, and branch. If a component is not specified at deploy time a default value will be used.

Unlike many charms in the Charmhub, the OpenStack Charms project leverages tracks extensively in order to manage a different array of supported charm versions for each supported combination of OpenStack release and Ubuntu series.

The Charmhub can be queried for a charm’s supported channels. For utmost clarity, this should be done on a per-series basis. For example, to query the channels for the glance charm on the ‘focal’ series:

juju info --series focal glance

Alternatively, the Charmhub web site can be visited: https://charmhub.io/glance

Important

For deployments that are running non-channel (legacy) charms, please see special charm operation All charms: migration to channels.

Tracks

A charm’s track corresponds to a given release of its payload. When the associated upstream project uses well-known release names, the track will use that name as its version number. Otherwise, the track’s name will typically be based on a version number or a release date. For example:

Charm

Example tracks

nova-compute

wallaby, xena

ceph-mon

octopus, pacific

rabbitmq-server

3.8, 3.9

ovn-central

21.03, 21.09

latest track

Generally speaking, the latest track is a special track whose purpose is to conveniently point to the latest version of a piece of software.

Warning

The OpenStack Charms project strongly advises against the use of the latest track due to its implicit nature. In doing so, a future charm upgrade may result in a charm version that does not support your current OpenStack release.

Risk levels

There are four risk levels that are potentially available for any track: edge, beta, candidate, and stable. Charms will be promoted through these levels based on the OpenStack Charms team policy on software maturity.

Branches

There is the possibility for a further subdivision of tracks and risk levels into Charmhub “branches”, which are meant to provide short-lived releases (e.g. quick bug fix).

Channels and tracks for OpenStack charms

Important

The information in this section will be updated as new tracks become available.

The below tables give the tracks that are available for several categories of charms. A mapping of tracks to both OpenStack release and Ubuntu series is also provided.

Note

The OpenStack service charms that support the following OpenStack releases will soon be managed by a single track: Queens, Rocky, Stein, and Train.

Group

Tracks

OpenStack

Series

OpenStack service charms

yoga

Yoga

jammy
focal

xena

Xena

focal

wallaby

Wallaby

victoria

Victoria

ussuri

Ussuri

focal
bionic

Ceph charms

quincy

Yoga

jammy
focal

pacific

Xena
Wallaby

focal

octopus

Victoria

Ussuri

focal
bionic

nautilus

Train

bionic

mimic

Stein
Rocky

luminous

Queens

OVN charms

22.03

Yoga

jammy
focal

21.09

Xena

focal

20.12

Wallaby

20.03

Victoria

Ussuri

focal
bionic

MySQL charms

8.0

Yoga

jammy
focal

Provider-specific subordinate charms

Some services interact with provider-specific subordinate charms in order to enable a specific SDN, storage plugin, etc. Although these are considered supporting charms, they nonetheless often enable specific functionality for an OpenStack service. They therefore follow the same track-naming schema as do the OpenStack service charms.

This is the list of provider-specific subordinate charms:

  • cinder-ceph

  • cinder-lvm

  • cinder-netapp

  • cinder-purestorage

  • neutron-openvswitch

  • neutron-api-plugin-arista

  • neutron-api-plugin-ironic

  • neutron-api-plugin-ovn

  • keystone-saml-mellon

Installation sources

Most charms in the OpenStack Charm project support either the openstack-origin or source configuration option. This options sets the software sources of the hosting machine.

In order to ensure that a charm’s channel will lead to the installation of the correct software version, these options will be set automatically according to the associated track. This is particularly important when a track spans multiple series (e.g. Ussuri is supported on both the ‘bionic’ and ‘focal’ series).