OpenStack, Ceph, OVN and support charms new default channel + retiring latest/stable

We are closing the latest/stable channel, and changing the default channel, for the OpenStack, Ceph, OVN and support charms. The new default channel will map to the most appropriate one for the current LTS: 22.04, which means Yoga OpenStack, Quincy Ceph and the 22.03 release of OVN.

In practice this won’t affect anyone using bundles (assuming they are reasonably up to date) as they tend to use explicit charmhub tracks/channels; do check your bundle!

It also won’t affect you if you’ve already deployed from latest/stable or were/are using the Juju 2.8 client. This only affects new installs that don’t use an explicit channel: specification in the bundle or when using imperative juju deploy commands without a --channel option.

The following provides a bit more detail and background to understand why this decision was made.


The latest/stable channel across the OpenStack, Ceph, OVN and miscellaneous charms contains the (now) outdated 21.10 (and older) releases of the OpenStack suite of charms. This was maintained during the charmstore to charmhub migration to provide a default for Juju 2.8 client/controllers to still be able to access compatible charms as Juju 2.8 isn’t charmhub-channel aware.

However, this is causing issues as latest/stable is the default branch and new users that don’t use a specific channel are getting old charms, which are unmaintained and don’t support the newer releases of OpenStack, Ceph and OVN.

The latest/stable channel for the OpenStack, Ceph, OVN and miscellaneous charms contains a set of revisions that were imported from the charmstore. Therefore, for some charms, they contain bases for Precise (say), and the most recent versions are for Focal from the 21.10 release of the charms.

This means that a juju deploy (without specifying a channel) will, at best, get a focal charm with the openstack-origin=distro, which would select a focal-ussuri OpenStack), and at worst (the vault charm), get a 21.10 vault charm with snap vault 1.10 (the current default track). In the latter case, this has never been tested and frankly, doesn’t work.

This obviously provides a poor experience!

New default channel

Each of the charms will have a new default channel that will provide the recommended combination of charms for the 22.04 LTS. These are:

  • OpenStack charms: channel yoga
  • Ceph charms: channel quincy
  • OVN charms: channel 22.03
  • hacluster - channel 2.4
  • mysql-innodb-cluster - channel 8.0
  • mysql-router - channel 8.0
  • percona-cluster - channel 5.7
  • rabbitmq-server - channel 3.9
  • vault - channel 1.8
  • openstack-loadbalancer - channel jammy
  • pacemaker-remote - channle jammy


This will be happening over the next two weeks.

What’s happening?

  1. The existing revisions have been recorded in the charm-guide to provide a reference for the last released Juju 2.8 compatible charms mapped against bases.
  2. New default channels will be set for all the charms.
  3. the latest/stable channel will be closed.

Note that the charm revision numbers on the latest/stable channel are no longer supported, but are being recorded so that operators/users can understand what is/was available. There are replacement revisions for all supported versions of OpenStack, Ceph and OVN in the stable channels for each charm.

Closing the latest/stable channel

Closing the latest/stable channel results in two outcomes:

  1. For new installs, where the operator doesn’t select a channel, the charms will be a consistent set that work with the current 22.04 LTS. The default stable channel means that the charms will get stable updates to the charm for their OpenStack version.
  2. For existing installs that were installed previously on Juju 2.8 (implicitly latest/stable channel), there will be no charm upgrade offered until the channel is switched. This means that their existing install remains stable, but they may choose to switch to a OpenStack release channel and then get updates to the charms. It is necessary to upgrade to Juju 2.9 (client and controller) to be able to switch to a new channel.


If you have any questions or comments, then please drop a reply here, or alternatively, reach out to us in the public OpenStack channel on, or on #openstack-charms on OFTC IRC or on the OpenStack discuss mailing list using the subject prefix “[charms]”

Thanks for reading this far!