Appendix B: OpenStack upgrades


This document outlines how to upgrade a Juju-deployed OpenStack cloud.


Upgrading an OpenStack cloud is not risk-free. The procedures outlined in this guide should first be tested in a pre-production environment.

Please read the following before continuing:


Charm upgrade

An upgrade of the charm software which is used to deploy and manage OpenStack. This includes charms that manage applications which are not technically part of the OpenStack project such as Rabbitmq and MySQL.

OpenStack upgrade

An upgrade of the OpenStack software (packages) that are installed and managed by the charms. Each OpenStack service is upgraded (by the operator) via its corresponding (and upgraded) charm. This constitutes an upgrade from one major release to the next (e.g. Stein to Train).

Ubuntu Server package upgrade

An upgrade of the software packages on a Juju machine that are not part of the OpenStack project (e.g. kernel modules, QEMU binaries, KVM kernel module).

Series upgrade

An upgrade of the operating system (Ubuntu) on a Juju machine (e.g. Xenial to Bionic). See appendix Series upgrade for more information.

Charm upgrades

All charms should be upgraded to their latest stable revision prior to performing the OpenStack upgrade. The Juju command to use is upgrade-charm. For extra guidance see Upgrading applications in the Juju documentation.


A charm upgrade affects all corresponding units; per-unit upgrades is not currently supported.

Although it may be possible to upgrade some charms in parallel it is recommended that the upgrades be performed sequentially (i.e. one at a time). Verify a charm upgrade before moving on to the next.

In terms of the upgrade order, begin with ‘keystone’. After that, the rest of the charms can be upgraded in any order.

Do check the Release Notes for any special instructions regarding charm upgrades.


Any software changes that may have (exceptionally) been made to a charm currently running on a unit will be overwritten by the target charm during the upgrade.

Before upgrading, a (partial) output to juju status may look like:

App       Version  Status   Scale  Charm     Store       Rev  OS      Notes
keystone  15.0.0   active       1  keystone  jujucharms  306  ubuntu

Unit             Workload  Agent  Machine  Public address  Ports      Message
keystone/0*      active    idle   3/lxd/1    5000/tcp   Unit is ready

Here, as deduced from the Keystone service version of ‘15.0.0’, the cloud is running Stein. The ‘keystone’ charm however shows a revision number of ‘306’. Upon charm upgrade, the service version will remain unchanged but the charm revision is expected to increase in number.

So to upgrade this ‘keystone’ charm (to the most recent promulgated version in the Charm Store):

juju upgrade-charm keystone

The upgrade progress can be monitored via juju status. Any encountered problem will surface as a message in its output. This sample (partial) output reflects a successful upgrade:

App       Version  Status   Scale  Charm     Store       Rev  OS      Notes
keystone  15.0.0   active       1  keystone  jujucharms  309  ubuntu

Unit             Workload  Agent  Machine  Public address  Ports      Message
keystone/0*      active    idle   3/lxd/1    5000/tcp   Unit is ready

This shows that the charm now has a revision number of ‘309’ but Keystone itself remains at ‘15.0.0’.

Upgrade target revisions

By default the upgrade-charm command will upgrade a charm to its latest stable revision (a possible multi-step upgrade). This means that intervening revisions can be conveniently skipped. Use the --revision option to specify a target revision.

The current revision can be discovered via juju status output (see column ‘Rev’). For the ceph-mon charm:

App       Version  Status  Scale  Charm     Store       Rev  OS      Notes
ceph-mon  13.2.8   active      3  ceph-mon  jujucharms   48  ubuntu

The latest available stable revision of a charm can be obtained by querying the Charm Store with the charm snap:

sudo snap install charm --classic
charm pull ceph-mon

Sample output:


Based on the above, the ceph-mon charm does not require an upgrade.


As stated earlier, any kind of upgrade should first be tested in a pre-production environment. OpenStack charm upgrades have been tested for single-step upgrades only (N+1).

OpenStack upgrades

Go through each of the following sections to ensure a trouble-free OpenStack upgrade.


The charms only support single-step OpenStack upgrades (N+1). That is, to upgrade two releases forward you need to upgrade twice. You cannot skip releases when upgrading OpenStack with charms.

It may be worthwhile to read the upstream OpenStack Upgrades guide.

Release Notes

The OpenStack charms Release Notes for the corresponding current and target versions of OpenStack must be consulted for any special instructions. In particular, pay attention to services and/or configuration options that may be retired, deprecated, or changed.

Manual intervention

It is intended that the now upgraded charms are able to accommodate all software changes associated with the corresponding OpenStack services to be upgraded. A new charm will also strive to produce a service as similarly configured to the pre-upgraded service as possible. Nevertheless, there are still times when intervention on the part of the operator may be needed, such as when:

  • a service is removed, added, or replaced

  • a software bug affecting the OpenStack upgrade is present in the new charm

All known issues requiring manual intervention are documented in section Known OpenStack upgrade issues. You must look these over.

Verify the current deployment

Confirm that the output for the juju status command of the current deployment is error-free. In addition, if monitoring is in use (e.g. Nagios), ensure that all alerts have been resolved. This is to make certain that any issues that may appear after the upgrade are not for pre-existing problems.

Perform a database backup

Before making any changes to cloud services perform a backup of the cloud database by running the backup action on any single percona-cluster unit:

juju run-action --wait percona-cluster/0 backup

Now transfer the backup directory to the Juju client with the intention of subsequently storing it somewhere safe. This command will grab all existing backups:

juju scp -- -r percona-cluster/0:/opt/backups/mysql /path/to/local/directory

Permissions may first need to be altered on the remote machine.

Archive old database data

During the upgrade, database migrations will be run. This operation can be optimised by first archiving any stale data (e.g. deleted instances). Do this by running the archive-data action on any single nova-cloud-controller unit:

juju run-action --wait nova-cloud-controller/0 archive-data

This action may need to be run multiple times until the action output reports ‘Nothing was archived’.

Purge old compute service entries

Old compute service entries for units which are no longer part of the model should be purged before the upgrade. These entries will show as ‘down’ (and be hosted on machines no longer in the model) in the current list of compute services:

openstack compute service list

To remove a compute service:

openstack compute service delete <service-id>

Disable unattended-upgrades

When performing a service upgrade on a unit that hosts multiple principle charms (e.g. nova-compute and ceph-osd), ensure that unattended-upgrades is disabled on the underlying machine for the duration of the upgrade process. This is to prevent the other services from being upgraded outside of Juju’s control. On a unit run:

sudo dpkg-reconfigure -plow unattended-upgrades

Upgrade order

The charms are put into groups to indicate the order in which their corresponding OpenStack services should be upgraded. The order within a group is unimportant. What matters is that all the charms within the same group are acted on before those in the next group (i.e. upgrade all charms in group 2 before moving on to group 3). Any Release Notes guidance overrides the information listed here. You may also consult the upstream documentation on the subject: Update services.

Each service represented by a charm in the below table will need to be upgraded individually.


Charm Name

Charm Type



Core Identity





















Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane



Control Plane





OpenStack services whose software is not a part of the Ubuntu Cloud Archive are not represented in the above list. This type of software can only have their major versions changed during a series (Ubuntu) upgrade on the associated unit. Common charms where this applies are ntp, memcached, percona-cluster, and rabbitmq-server.

Perform the upgrade

The essence of a charmed OpenStack service upgrade is a change of the corresponding machine software sources so that a more recent combination of Ubuntu release and OpenStack release is used. This combination is based on the Ubuntu Cloud Archive and translates to a “cloud archive OpenStack release”. It takes on the following syntax:

<ubuntu series>-<openstack-release>

For example, the ‘bionic-train’ UCA release is expressed during configuration as:


There are three methods available for performing an OpenStack service upgrade. The appropriate method is chosen based on the actions supported by the charm. Actions for a charm can be listed in this way:

juju actions <charm-name>


The “all-in-one” method upgrades an application immediately. Although it is the quickest route, it can be harsh when applied in the context of multi-unit applications. This is because all the units are upgraded simultaneously, and is likely to cause a transient service outage. This method must be used if the application has a sole unit.


The “all-in-one” method should only be used when the charm does not support the openstack-upgrade action.

The syntax is:

juju config <openstack-charm> openstack-origin=cloud:<cloud-archive-release>

Charms whose services are not technically part of the OpenStack project will use the source charm option instead. The Ceph charms are a classic example:

juju config ceph-mon source=cloud:bionic-train


The ceph-osd and ceph-mon charms are able to maintain service availability during the upgrade.

So to upgrade Cinder across all units (currently running Bionic) from Stein to Train:

juju config cinder openstack-origin=cloud:bionic-train


The “single-unit” method builds upon the “all-in-one” method by allowing for the upgrade of individual units in a controlled manner. It requires the enablement of charm option action-managed-upgrade and the charm action openstack-upgrade.


The “single-unit” method should only be used when the charm does not support the pause and resume actions.

As a general rule, whenever there is the possibility of upgrading units individually, always upgrade the application leader first. The leader is the unit with a * next to it in the juju status output. It can also be discovered via the CLI:

juju run --application <application-name> is-leader

For example, to upgrade a three-unit glance application from Stein to Train where glance/1 is the leader:

juju config glance action-managed-upgrade=True
juju config glance openstack-origin=cloud:bionic-train

juju run-action --wait glance/1 openstack-upgrade
juju run-action --wait glance/0 openstack-upgrade
juju run-action --wait glance/2 openstack-upgrade


The openstack-upgrade action is only available for charms whose services are part of the OpenStack project. For instance, you will need to use the “all-in-one” method for the Ceph charms.


The “paused-single-unit” method extends the “single-unit” method by allowing for the upgrade of individual units while paused. Additional charm requirements are the pause and resume actions. This method provides more versatility by allowing a unit to be removed from service, upgraded, and returned to service. Each of these are distinct events whose timing is chosen by the operator.


The “paused-single-unit” method is the recommended OpenStack service upgrade method.

For example, to upgrade a three-unit nova-compute application from Stein to Train where nova-compute/0 is the leader:

juju config nova-compute action-managed-upgrade=True
juju config nova-compute openstack-origin=cloud:bionic-train

juju run-action nova-compute/0 --wait pause
juju run-action nova-compute/0 --wait openstack-upgrade
juju run-action nova-compute/0 --wait resume

juju run-action nova-compute/1 --wait pause
juju run-action nova-compute/1 --wait openstack-upgrade
juju run-action nova-compute/1 --wait resume

juju run-action nova-compute/2 --wait pause
juju run-action nova-compute/2 --wait openstack-upgrade
juju run-action nova-compute/2 --wait resume

In addition, this method also permits a possible hacluster subordinate unit, which typically manages a VIP, to be paused so that client traffic will not flow to the associated parent unit while its upgrade is underway.


When there is an hacluster subordinate unit then it is recommended to always take advantage of the “pause-single-unit” method’s ability to pause it before upgrading the parent unit.

For example, to upgrade a three-unit keystone application from Stein to Train where keystone/2 is the leader:

juju config keystone action-managed-upgrade=True
juju config keystone openstack-origin=cloud:bionic-train

juju run-action keystone-hacluster/1 --wait pause
juju run-action keystone/2 --wait pause
juju run-action keystone/2 --wait openstack-upgrade
juju run-action keystone/2 --wait resume
juju run-action keystone-hacluster/1 --wait resume

juju run-action keystone-hacluster/2 --wait pause
juju run-action keystone/1 --wait pause
juju run-action keystone/1 --wait openstack-upgrade
juju run-action keystone/1 --wait resume
juju run-action keystone-hacluster/2 --wait resume

juju run-action keystone-hacluster/0 --wait pause
juju run-action keystone/0 --wait pause
juju run-action keystone/0 --wait openstack-upgrade
juju run-action keystone/0 --wait resume
juju run-action keystone-hacluster/0 --wait resume


The hacluster subordinate unit number may not necessarily match its parent unit number. As in the above example, only for keystone/0 do the unit numbers correspond (i.e. keystone-hacluster/0 is the subordinate unit).

Verify the new deployment

Check for errors in juju status output and any monitoring service.

Known OpenStack upgrade issues

Nova RPC version mismatches

If it is not possible to upgrade Neutron and Nova within the same maintenance window, be mindful that the RPC communication between nova-cloud-controller, nova-compute, and nova-api-metadata is very likely to cause several errors while those services are not running the same version. This is due to the fact that currently those charms do not support RPC version pinning or auto-negotiation.

See bug LP #1825999.

neutron-gateway charm: upgrading from Mitaka to Newton

Between the Mitaka and Newton OpenStack releases, the neutron-gateway charm added two options, bridge-mappings and data-port, which replaced the (now) deprecated ext-port option. This was to provide for more control over how neutron-gateway can configure external networking. Unfortunately, the charm was only designed to work with either ext-port (no longer recommended) or bridge-mappings and data-port.

See bug LP #1809190.

cinder/ceph topology change: upgrading from Newton to Ocata

If cinder is directly related to ceph-mon rather than via cinder-ceph then upgrading from Newton to Ocata will result in the loss of some block storage functionality, specifically live migration and snapshotting. To remedy this situation the deployment should migrate to using the cinder-ceph charm. This can be done after the upgrade to Ocata.


Do not attempt to migrate a deployment with existing volumes to use the cinder-ceph charm prior to Ocata.

The intervention is detailed in the below three steps.

Step 0: Check existing configuration

Confirm existing volumes are in an RBD pool called ‘cinder’:

juju run --unit cinder/0 "rbd --name client.cinder -p cinder ls"

Sample output:


Step 1: Deploy new topology

Deploy the cinder-ceph charm and set the ‘rbd-pool-name’ to match the pool that any existing volumes are in (see above):

juju deploy --config rbd-pool-name=cinder cinder-ceph
juju add-relation cinder cinder-ceph
juju add-relation cinder-ceph ceph-mon
juju remove-relation cinder ceph-mon
juju add-relation cinder-ceph nova-compute

Step 2: Update volume configuration

The existing volumes now need to be updated to associate them with the newly defined cinder-ceph backend:

juju run-action cinder/0 rename-volume-host currenthost='cinder' \

Placement charm and nova-cloud-controller: upgrading from Stein to Train

As of Train, the placement API is managed by the new placement charm and is no longer managed by the nova-cloud-controller charm. The upgrade to Train therefore requires some coordination to transition to the new API endpoints.

Prior to upgrading nova-cloud-controller to Train, the placement charm must be deployed for Train and related to the Stein-based nova-cloud-controller. It is important that the nova-cloud-controller unit leader is paused while the API transition occurs (paused prior to adding relations for the placement charm) as the placement charm will migrate existing placement tables from the nova_api database to a new placement database. Once the new placement endpoints are registered, nova-cloud-controller can be resumed.

Here’s an example of the steps just described where nova-cloud-controller/0 is the leader:

juju deploy --series bionic --config openstack-origin=cloud:bionic-train cs:placement
juju run-action nova-cloud-controller/0 pause
juju add-relation placement mysql
juju add-relation placement keystone
juju add-relation placement nova-cloud-controller
openstack endpoint list # ensure placement endpoints are listening on new placment IP address
juju run-action nova-cloud-controller/0 resume

Only after these steps have been completed can nova-cloud-controller be upgraded. Here we upgrade all units simultaneously but see the Paused-single-unit service upgrade method for a more controlled approach:

juju config nova-cloud-controller openstack-origin=cloud:bionic-train

Neutron LBaaS: upgrading from Stein to Train

As of Train, support for Neutron LBaaS has been retired. The load-balancing services are now provided by Octavia LBaaS. There is no automatic migration path, please review the Octavia LBaaS appendix for more information.

openstack-dashboard charm: upgrading to revision 294

When Horizon is configured with TLS (openstack-dashboard charm option ssl-cert) revisions 294 and 295 of the charm have been reported to break the dashboard (see bug LP #1853173). The solution is to upgrade to a working revision. A temporary workaround is to disable TLS without upgrading.


Most users will not be impacted by this issue as the recommended approach is to always upgrade to the latest revision.

To upgrade to revision 293:

juju upgrade-charm openstack-dashboard --revision 293

To upgrade to revision 296:

juju upgrade-charm openstack-dashboard --revision 296

To disable TLS:

juju config enforce-ssl=false openstack-dashboard

Designate Upgrades to Train

When upgrading Designate to Train, there is an encoding issue between the designate-producer and memcached that causes the designate-producer to crash. See bug LP #1828534. This can be resolved by restarting the memcached service.

juju run --application=memcached 'sudo systemctl restart memcached'