Appendix F2: Series upgrade OpenStack

Overview

This document will provide specific steps for how to perform a series upgrade across the entirety of a Charmed OpenStack cloud.

Warning

This document is based upon the foundational knowledge and guidelines set forth in the more general Series upgrade appendix. That reference must be studied in-depth prior to attempting the steps outlined here. In particular, ensure that the Pre-upgrade requirements are satisfied; the Specific series upgrade procedures have been reviewed and considered; and that Workload specific preparations have been addressed during planning.

Downtime

Although the goal is to minimise downtime the series upgrade process across a cloud will nonetheless result in some level of downtime for the control plane.

When the machines associated with stateful applications such as percona-cluster and rabbitmq-server undergo a series upgrade all cloud APIs will experience downtime, in addition to the stateful application itself.

When machines associated with a single API application undergo a series upgrade that individual API will also experience downtime. This is because it is necessary to pause services in order to avoid race condition errors.

For those applications working in tandem with hacluster, as will be shown, some hacluster units will need to be paused before the upgrade. One should assume that the commencement of an outage coincides with this step (it will cause cluster quorum heartbeats to fail and the service VIP will consequently go offline).

Reference cloud topology

This section describes a hyperconverged cloud topology that this document will use for the procedural steps to follow. Hyperconvergence refers to the practice of co-locating principle applications on the same machine.

The topology is defined in this way:

  • Only compute and storage charms (and their subordinates) may be co-located.

  • Third-party charms either do not exist or have been thoroughly tested for a series upgrade.

  • The following are containerised:

    • All API applications

    • The percona-cluster application

    • The rabbitmq-server application

    • The ceph-mon application

Storage charms are charms that manage physical disks. For example, ceph-osd and swift-storage. Example OpenStack subordinate charms are networking SDN charms for the nova-compute charm, or monitoring charms for compute or storage charms.

Caution

If your cloud differs from this topology you must adapt the procedural steps accordingly. In particular, look at the aspects of co-located applications and containerised applications. Recall that:

  • the upgrade-series command:

    • affects all applications residing on the target machine

    • does not affect containers hosted on the target machine

  • an application’s leader should be upgraded before its non-leaders

Generalised OpenStack series upgrade

This section will summarise the series upgrade steps in the context of specific OpenStack applications. It is an enhancement of the Generic series upgrade section in the companion document.

Applications for which this summary does not apply include:

  • nova-compute

  • ceph-mon

  • ceph-osd

This is because the above applications do not require the pausing of units and application leadership is irrelevant for them.

However, this summary does apply to all API applications (e.g. neutron-api, keystone, nova-cloud-controller), as well as percona-cluster, and rabbitmq-server.

Important

The first machine to be upgraded is always associated with the leader of the principle application. Let this machine be called the “principle leader machine” and its unit be called the “principle leader unit”.

The steps are as follows:

  1. Set the default series for the principle application and ensure the same has been done to the model.

  2. If hacluster is used, pause the hacluster units not associated with the principle leader machine.

  3. Pause the principle non-leader units.

  4. Perform a series upgrade on the principle leader machine.

    1. Perform any pre-upgrade workload maintenance tasks.

    2. Invoke the prepare sub-command.

    3. Upgrade the operating system (APT commands).

    4. Perform any post-upgrade workload maintenance tasks.

    5. Reboot.

  5. Set the value of the (application-dependent) openstack-origin or the source configuration option to ‘distro’ (new operating system).

  6. Invoke the complete sub-command on the principle leader machine.

  7. Repeat steps 4 and 6 for the application non-leader machines.

  8. Perform any possible cluster completed upgrade tasks once all machines have had their series upgraded.

    Note

    Here is a non-extensive list of the most common post-upgrade tasks for OpenStack and supporting charms:

    • percona-cluster: run action complete-cluster-series-upgrade on the leader unit.

    • rabbitmq-server: run action complete-cluster-series-upgrade on the leader unit.

    • ceilometer: run action ceilometer-upgrade on the leader unit.

    • vault: Each vault unit will need to be unsealed after its machine is rebooted.

Procedures

The procedures are categorised based on application types. The example scenario used throughout is a ‘xenial’ to ‘bionic’ series upgrade, within an OpenStack release of Queens (i.e. the starting point is a cloud archive pocket of ‘xenial-queens’).

Stateful applications

This section covers the series upgrade procedure for containerised stateful applications. These include:

  • ceph-mon

  • percona-cluster

  • rabbitmq-server

A stateful application is one that maintains the state of various aspects of the cloud. Clustered stateful applications, such as all the ones given above, also require a quorum to function properly. Because of these reasons a stateful application should not have all of its units restarted simultaneously; it must have the series of its corresponding machines upgraded sequentially.

Note

The concurrent upgrade approach is theoretically possible, although to use it all cloud workloads will need to be stopped in order to ensure consistency. This is not recommended.

The example procedure will be based on the percona-cluster application.

Important

Unlike percona-cluster, the ceph-mon and rabbitmq-server applications do not use hacluster to achieve HA, nor do they need backups. Disregard therefore the hacluster and backup steps for these two applications.

The ceph-mon charm will maintain the MON cluster during a series upgrade, so ceph-mon units do not need to be paused.

This scenario is represented by the following partial juju status command output:

Model    Controller       Cloud/Region    Version  SLA          Timestamp
upgrade  maas-controller  mymaas/default  2.7.6    unsupported  18:26:57Z

App                        Version  Status  Scale  Charm            Store       Rev  OS      Notes
percona-cluster            5.6.37   active      3  percona-cluster  jujucharms  286  ubuntu
percona-cluster-hacluster           active      3  hacluster        jujucharms   66  ubuntu

Unit                            Workload  Agent  Machine  Public address  Ports     Message
percona-cluster/0               active    idle   0/lxd/0  10.0.0.47       3306/tcp  Unit is ready
  percona-cluster-hacluster/0*  active    idle            10.0.0.47                 Unit is ready and clustered
percona-cluster/1*              active    idle   1/lxd/0  10.0.0.48       3306/tcp  Unit is ready
  percona-cluster-hacluster/2   active    idle            10.0.0.48                 Unit is ready and clustered
percona-cluster/2               active    idle   2/lxd/0  10.0.0.49       3306/tcp  Unit is ready
  percona-cluster-hacluster/1   active    idle            10.0.0.49                 Unit is ready and clustered

In summary, the principle leader unit is percona-cluster/1 and is deployed on machine 1/lxd/0 (the principle leader machine).

Warning

During this upgrade, there will be a MySQL service outage. The HA resources provided by hacluster will not be monitored during the series upgrade due to the pausing of units.

  1. Perform any workload maintenance pre-upgrade steps. For percona-cluster, take a backup and transfer it to a secure location:

    juju run-action --wait percona-cluster/1 backup
    juju scp -- -r percona-cluster/1:/opt/backups/mysql /path/to/local/directory
    

    Permissions will need to be altered on the remote machine, and note that the last command transfers all existing backups.

  2. Set the default series for both the model and the principle application:

    juju model-config default-series=bionic
    juju set-series percona-cluster bionic
    
  3. Pause the hacluster units not associated with the principle leader machine:

    juju run-action --wait percona-cluster-hacluster/0 pause
    juju run-action --wait percona-cluster-hacluster/1 pause
    
  4. Pause the principle non-leader units:

    juju run-action --wait percona-cluster/0 pause
    juju run-action --wait percona-cluster/2 pause
    

    For percona-cluster, leaving the principle leader unit up will ensure it has the latest MySQL sequence number; it will be considered the most up to date cluster member.

  5. Perform a series upgrade on the principle leader machine:

    juju upgrade-series 1/lxd/0 prepare bionic
    juju run --machine=1/lxd/0 -- sudo apt update
    juju ssh 1/lxd/0 sudo apt full-upgrade
    juju ssh 1/lxd/0 sudo do-release-upgrade
    

    For percona-cluster, there are no post-upgrade steps; the prompt to reboot can be answered in the affirmative.

  6. Set the value of the source configuration option to ‘distro’:

    juju config percona-cluster source=distro
    
  7. Invoke the complete sub-command on the principle leader machine:

    juju upgrade-series 1/lxd/0 complete
    

    At this point the juju status output looks like this:

    Model    Controller       Cloud/Region    Version  SLA          Timestamp
    upgrade  maas-controller  mymaas/default  2.7.6    unsupported  19:51:52Z
    
    App                        Version  Status       Scale  Charm            Store       Rev  OS      Notes
    percona-cluster            5.7.20   maintenance      3  percona-cluster  jujucharms  286  ubuntu
    percona-cluster-hacluster           blocked          3  hacluster        jujucharms   66  ubuntu
    
    Unit                            Workload     Agent  Machine  Public address  Ports     Message
    percona-cluster/0               maintenance  idle   0/lxd/0  10.0.0.47       3306/tcp  Paused. Use 'resume' action to resume normal service.
      percona-cluster-hacluster/0*  maintenance  idle            10.0.0.47                 Paused. Use 'resume' action to resume normal service.
    percona-cluster/1*              active       idle   1/lxd/0  10.0.0.48       3306/tcp  Unit is ready
      percona-cluster-hacluster/2   blocked      idle            10.0.0.48                 Resource: res_mysql_11810cc_vip not running
    percona-cluster/2               maintenance  idle   2/lxd/0  10.0.0.49       3306/tcp  Paused. Use 'resume' action to resume normal service.
      percona-cluster-hacluster/1   maintenance  idle            10.0.0.49                 Paused. Use 'resume' action to resume normal service.
    
    Machine  State    DNS        Inst id              Series  AZ     Message
    0        started  10.0.0.44  node1                xenial  zone1  Deployed
    0/lxd/0  started  10.0.0.47  juju-f83fcd-0-lxd-0  xenial  zone1  Container started
    1        started  10.0.0.45  node2                xenial  zone2  Deployed
    1/lxd/0  started  10.0.0.48  juju-f83fcd-1-lxd-0  bionic  zone2  Running
    2        started  10.0.0.46  node3                xenial  zone3  Deployed
    2/lxd/0  started  10.0.0.49  juju-f83fcd-2-lxd-0  xenial  zone3  Container started
    
  8. For percona-cluster, a sanity check should be done on the leader unit’s databases and data.

  9. Repeat steps 5 and 7 for the principle non-leader machines.

  10. Perform any possible cluster completed upgrade tasks once all machines have had their series upgraded:

    juju run-action --wait percona-cluster/leader complete-cluster-series-upgrade
    

    For percona-cluster (and rabbitmq-server), the above action is performed on the leader unit. It informs each cluster node that the upgrade process is complete cluster-wide. This also updates MySQL configuration with all peers in the cluster.

API applications

This section covers series upgrade procedures for containerised API applications. These include, but are not limited to:

  • cinder

  • glance

  • keystone

  • neutron-api

  • nova-cloud-controller

Machines hosting API applications can have their series upgraded concurrently because those applications are stateless. This results in a dramatically reduced downtime for the application. A sequential approach will not reduce downtime as the HA services will still need to be brought down during the upgrade associated with the application leader.

The following two sub-sections will show how to perform a series upgrade concurrently for a single API application and for multiple API applications.

Upgrading a single API application concurrently

This example procedure will be based on the keystone application.

This scenario is represented by the following partial juju status command output:

Model    Controller       Cloud/Region    Version  SLA          Timestamp
upgrade  maas-controller  mymaas/default  2.7.6    unsupported  22:48:41Z

App                 Version  Status  Scale  Charm            Store       Rev  OS      Notes
keystone            13.0.2   active      3  keystone         jujucharms  312  ubuntu
keystone-hacluster           active      3  hacluster        jujucharms   66  ubuntu

Unit                     Workload  Agent  Machine  Public address  Ports     Message
keystone/0*              active    idle   0/lxd/0  10.0.0.70       5000/tcp  Unit is ready
  keystone-hacluster/0*  active    idle            10.0.0.70                 Unit is ready and clustered
keystone/1               active    idle   1/lxd/0  10.0.0.71       5000/tcp  Unit is ready
  keystone-hacluster/2   active    idle            10.0.0.71                 Unit is ready and clustered
keystone/2               active    idle   2/lxd/0  10.0.0.72       5000/tcp  Unit is ready
  keystone-hacluster/1   active    idle            10.0.0.72                 Unit is ready and clustered

In summary, the principle leader unit is keystone/0 and is deployed on machine 0/lxd/0 (the principle leader machine).

  1. Set the default series for both the model and the principle application:

    juju model-config default-series=bionic
    juju set-series keystone bionic
    
  2. Pause the hacluster units not associated with the principle leader machine:

    juju run-action --wait keystone-hacluster/1 pause
    juju run-action --wait keystone-hacluster/2 pause
    
  3. Pause the principle non-leader units:

    juju run-action --wait keystone/1 pause
    juju run-action --wait keystone/2 pause
    
  4. Perform any workload maintenance pre-upgrade steps on all machines. There are no keystone-specific steps to perform.

  5. Invoke the prepare sub-command on all machines, starting with the principle leader machine:

    juju upgrade-series 0/lxd/0 prepare bionic
    juju upgrade-series 1/lxd/0 prepare bionic
    juju upgrade-series 2/lxd/0 prepare bionic
    

    At this point the juju status output looks like this:

    Model    Controller       Cloud/Region    Version  SLA          Timestamp
    upgrade  maas-controller  mymaas/default  2.7.6    unsupported  23:11:01Z
    
    App                 Version  Status   Scale  Charm            Store       Rev  OS      Notes
    keystone            13.0.2   blocked      3  keystone         jujucharms  312  ubuntu
    keystone-hacluster           blocked      3  hacluster        jujucharms   66  ubuntu
    
    Unit                     Workload  Agent  Machine  Public address  Ports     Message
    keystone/0*              blocked   idle   0/lxd/0  10.0.0.70       5000/tcp  Ready for do-release-upgrade and reboot. Set complete when finished.
      keystone-hacluster/0*  blocked   idle            10.0.0.70                 Ready for do-release-upgrade. Set complete when finished
    keystone/1               blocked   idle   1/lxd/0  10.0.0.71       5000/tcp  Ready for do-release-upgrade and reboot. Set complete when finished.
      keystone-hacluster/2   blocked   idle            10.0.0.71                 Ready for do-release-upgrade. Set complete when finished
    keystone/2               blocked   idle   2/lxd/0  10.0.0.72       5000/tcp  Ready for do-release-upgrade and reboot. Set complete when finished.
      keystone-hacluster/1   blocked   idle            10.0.0.72                 Ready for do-release-upgrade. Set complete when finished
    
  6. Upgrade the operating system on all machines. The non-interactive method is used here:

    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0 --timeout=10m \
       -- sudo apt-get update
    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0 --timeout=60m \
       -- sudo DEBIAN_FRONTEND=noninteractive apt-get --assume-yes \
       -o "Dpkg::Options::=--force-confdef" \
       -o "Dpkg::Options::=--force-confold" dist-upgrade
    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0 --timeout=120m \
       -- sudo DEBIAN_FRONTEND=noninteractive \
       do-release-upgrade -f DistUpgradeViewNonInteractive
    

    Important

    Choose values for the --timeout option that are appropriate for the task at hand.

  7. Perform any workload maintenance post-upgrade steps on all machines. There are no keystone-specific steps to perform.

  8. Reboot all machines:

    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0 -- sudo reboot
    
  9. Set the value of the openstack-origin configuration option to ‘distro’:

    juju config keystone openstack-origin=distro
    
  10. Invoke the complete sub-command on all machines:

    juju upgrade-series 0/lxd/0 complete
    juju upgrade-series 1/lxd/0 complete
    juju upgrade-series 2/lxd/0 complete
    

Upgrading multiple API applications concurrently

This example procedure will be based on the nova-cloud-controller and glance applications.

This scenario is represented by the following partial juju status command output:

Model    Controller       Cloud/Region    Version  SLA          Timestamp
upgrade  maas-controller  mymaas/default  2.7.6    unsupported  19:23:41Z

App                    Version  Status  Scale  Charm                  Store       Rev  OS      Notes
glance                 16.0.1   active      3  glance                 jujucharms  295  ubuntu
glance-hacluster                active      3  hacluster              jujucharms   66  ubuntu
nova-cc-hacluster               active      3  hacluster              jujucharms   66  ubuntu
nova-cloud-controller  17.0.12  active      3  nova-cloud-controller  jujucharms  343  ubuntu

Unit                      Workload  Agent  Machine  Public address  Ports              Message
glance/0*                 active    idle   0/lxd/0  10.246.114.39   9292/tcp           Unit is ready
  glance-hacluster/0*     active    idle            10.246.114.39                      Unit is ready and clustered
glance/1                  active    idle   1/lxd/0  10.246.114.40   9292/tcp           Unit is ready
  glance-hacluster/1      active    idle            10.246.114.40                      Unit is ready and clustered
glance/2                  active    idle   2/lxd/0  10.246.114.41   9292/tcp           Unit is ready
  glance-hacluster/2      active    idle            10.246.114.41                      Unit is ready and clustered
nova-cloud-controller/0   active    idle   3/lxd/0  10.246.114.48   8774/tcp,8778/tcp  Unit is ready
  nova-cc-hacluster/2     active    idle            10.246.114.48                      Unit is ready and clustered
nova-cloud-controller/1*  active    idle   4/lxd/0  10.246.114.43   8774/tcp,8778/tcp  Unit is ready
  nova-cc-hacluster/0*    active    idle            10.246.114.43                      Unit is ready and clustered
nova-cloud-controller/2   active    idle   5/lxd/0  10.246.114.47   8774/tcp,8778/tcp  Unit is ready
  nova-cc-hacluster/1     active    idle            10.246.114.47                      Unit is ready and clustered

In summary,

  • The glance principle leader unit is glance/0 and is deployed on machine 0/lxd/0 (the glance principle leader machine).

  • The nova-cloud-controller principle leader unit is nova-cloud-controller/1 and is deployed on machine 4/lxd/0 (the nova-cloud-controller principle leader machine).

The procedure has been expedited slightly by adding the --yes confirmation option to the prepare sub-command.

  1. Set the default series for both the model and the principle applications:

    juju model-config default-series=bionic
    juju set-series glance bionic
    juju set-series nova-cloud-controller bionic
    
  2. Pause the hacluster units not associated with their principle leader machines:

    juju run-action --wait glance-hacluster/1 pause
    juju run-action --wait glance-hacluster/2 pause
    juju run-action --wait nova-cc-hacluster/1 pause
    juju run-action --wait nova-cc-hacluster/2 pause
    
  3. Pause the principle non-leader units:

    juju run-action --wait glance/1 pause
    juju run-action --wait glance/2 pause
    juju run-action --wait nova-cloud-controller/0 pause
    juju run-action --wait nova-cloud-controller/2 pause
    
  4. Perform any workload maintenance pre-upgrade steps on all machines. There are no glance-specific or nova-cloud-controller-specific steps to perform.

  5. Invoke the prepare sub-command on all machines, starting with the principle leader machines:

    juju upgrade-series --yes 0/lxd/0 prepare bionic
    juju upgrade-series --yes 4/lxd/0 prepare bionic
    juju upgrade-series --yes 1/lxd/0 prepare bionic
    juju upgrade-series --yes 2/lxd/0 prepare bionic
    juju upgrade-series --yes 3/lxd/0 prepare bionic
    juju upgrade-series --yes 5/lxd/0 prepare bionic
    
  6. Upgrade the operating system on all machines. The non-interactive method is used here:

    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0,3/lxd/0,4/lxd/0,5/lxd/0 \
       --timeout=20m -- sudo apt-get update
    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0,3/lxd/0,4/lxd/0,5/lxd/0 \
       --timeout=120m -- sudo DEBIAN_FRONTEND=noninteractive apt-get --assume-yes \
       -o "Dpkg::Options::=--force-confdef" \
       -o "Dpkg::Options::=--force-confold" dist-upgrade
    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0,3/lxd/0,4/lxd/0,5/lxd/0 \
       --timeout=200m -- sudo DEBIAN_FRONTEND=noninteractive \
       do-release-upgrade -f DistUpgradeViewNonInteractive
    
  7. Perform any workload maintenance post-upgrade steps on all machines. There are no glance-specific or nova-cloud-controller-specific steps to perform.

  8. Reboot all machines:

    juju run --machine=0/lxd/0,1/lxd/0,2/lxd/0,3/lxd/0,4/lxd/0,5/lxd/0 -- sudo reboot
    
  9. Set the value of the openstack-origin configuration option to ‘distro’:

    juju config glance openstack-origin=distro
    juju config nova-cloud-controller openstack-origin=distro
    
  10. Invoke the complete sub-command on all machines:

    juju upgrade-series 0/lxd/0 complete
    juju upgrade-series 1/lxd/0 complete
    juju upgrade-series 2/lxd/0 complete
    juju upgrade-series 3/lxd/0 complete
    juju upgrade-series 4/lxd/0 complete
    juju upgrade-series 5/lxd/0 complete
    

Physical machines

This section covers series upgrade procedures for applications hosted on physical machines in particular. These typically include:

  • ceph-osd

  • neutron-gateway

  • nova-compute

When performing a series upgrade on a physical machine more attention should be given to any workload maintenance pre-upgrade steps:

  • For compute nodes migrate all running VMs to another hypervisor.

  • For network nodes force HA routers off of the current node.

  • Any storage related tasks that may be required.

  • Any site specific tasks that may be required.

The following two sub-sections will show how to perform a series upgrade for a single physical machine and for multiple physical machines concurrently.

Upgrading a single physical machine

This example procedure will be based on the nova-compute and ceph-osd applications residing on the same physical machine. Since application leadership does not play a significant role with these two applications, and because the hacluster application is not present, there will be no units to pause (as there were in previous scenarios).

This scenario is represented by the following partial juju status command output:

Model    Controller       Cloud/Region    Version  SLA          Timestamp
upgrade  maas-controller  mymaas/default  2.7.6    unsupported  15:23:21Z

App           Version  Status  Scale  Charm         Store       Rev  OS      Notes
ceph-osd      12.2.12  active      1  ceph-osd      jujucharms  301  ubuntu
keystone      13.0.2   active      1  keystone      jujucharms  312  ubuntu
nova-compute  17.0.12  active      1  nova-compute  jujucharms  314  ubuntu

Unit             Workload  Agent  Machine  Public address  Ports     Message
ceph-osd/0*      active    idle   0        10.0.0.235                Unit is ready (1 OSD)
keystone/0*      active    idle   0/lxd/0  10.0.0.240      5000/tcp  Unit is ready
nova-compute/0*  active    idle   0        10.0.0.235                Unit is ready

Machine  State    DNS         Inst id              Series  AZ     Message
0        started  10.0.0.235  node1                xenial  zone1  Deployed
0/lxd/0  started  10.0.0.240  juju-88b27a-0-lxd-0  xenial  zone1  Container started

In summary, the ceph-osd and nova-compute applications are hosted on machine 0. Recall that container 0/lxd/0 will need to have its series upgraded separately.

  1. It is recommended to set the Ceph cluster OSDs to ‘noout’. This is typically done at the application level (i.e. not at the unit or machine level):

    juju run-action --wait ceph-mon/leader set-noout
    
  2. All running VMs should be migrated to another hypervisor.

  3. Upgrade the series on machine 0:

    1. Invoke the prepare sub-command:

      juju upgrade-series 0 prepare bionic
      
    2. Upgrade the operating system:

      juju run --machine=0 -- sudo apt update
      juju ssh 0 sudo apt full-upgrade
      juju ssh 0 sudo do-release-upgrade
      
    3. Reboot (if not already done):

      juju run --machine=0 -- sudo reboot
      
    4. Set the value of the openstack-origin or source configuration options to ‘distro’:

      juju config nova-compute openstack-origin=distro
      juju config ceph-osd source=distro
      
    5. Invoke the complete sub-command on the machine:

      juju upgrade-series 0 complete
      
  4. If OSDs were previously set to ‘noout’ then check up/in status of those OSDs in ceph status, then unset ‘noout’ for the cluster:

    juju run --unit ceph-mon/leader -- ceph status
    juju run-action --wait ceph-mon/leader unset-noout
    

Upgrading multiple physical hosts concurrently

When physical machines have their series upgraded concurrently Availability Zones need to be taken into account. Machines should be placed into upgrade groups such that any API services running on them have a maximum of one unit per group. This is to ensure API availability at the reboot stage.

This simplified bundle is used to demonstrate the general idea:

series: xenial
machines:
  0: {}
  1: {}
  2: {}
  3: {}
  4: {}
  5: {}
applications:
  nova-compute:
    charm: cs:nova-compute
    num_units: 3
    options:
      openstack-origin: cloud:xenial-queens
    to:
      - 0
      - 2
      - 4
  keystone:
    charm: cs:keystone
    constraints: mem=1G
    num_units: 3
    options:
      vip: 10.85.132.200
      openstack-origin: cloud:xenial-queens
    to:
      - lxd:1
      - lxd:3
      - lxd:5
  keystone-hacluster:
    charm: cs:hacluster
    options:
      cluster_count: 3

Three upgrade groups could consist of the following machines:

  1. Machines 0 and 1

  2. Machines 2 and 3

  3. Machines 4 and 5

In this way, a less time-consuming series upgrade can be performed while still ensuring the availability of services.

Caution

For the ceph-osd application, ensure that rack-aware replication rules exist in the CRUSH map if machines are being rebooted together. This is to prevent significant interruption to running workloads from occurring if the same placement group is hosted on those machines. For example, if ceph-mon is deployed with customize-failure-domain set to ‘true’ and the ceph-osd units are hosted on machines in three or more separate Juju AZs you can safely reboot ceph-osd machines concurrently in the same zone. See Ceph AZ in OpenStack high availability for details.

Automation

Series upgrades across an OpenStack cloud can be time consuming, even when using concurrent methods wherever possible. They can also be tedious and thus susceptible to human error.

The following code examples encapsulate the processes described in this document. They are provided solely to illustrate the methods used to develop and test the series upgrade primitives:

  • Parallel tests: An example that is used as a functional verification of a series upgrade in the OpenStack Charms project.

  • Upgrade helpers: A set of helpers used in the above upgrade example.

Caution

The example code should only be used for its intended use case of development and testing. Do not attempt to automate a series upgrade on a production cloud.