Planning

The plan has a tree structure with six main sections:

• cloud pre-upgrade steps,

• control-plane principal applications upgrade

• control-plane subordinate applications upgrade

• data-plane hypervisors upgrade

• data-plane non-hypervisor principal applications upgrade

• data-plane subordinate applications upgrade

• cloud post-upgrade steps.

Upgrade cloud from current release to target release
    cloud pre-upgrade steps
        Verify cloud is in idle state
        MySQL backup
    control-plane principal applications upgrade
            application 1
                pre-upgrade steps
                upgrade steps
                post-upgrade steps
            ...
            application N
                ...
    control-plane subordinate applications upgrade
            application M
                ...
    data-plane hypervisors upgrade
            availability zone 1
                pre-upgrade steps
                upgrade steps
                    Ψ unit 1
                        unit upgrade step A
                        ...
                        unit upgrade step Z
                    ...
                    Ψ unit K
                        unit upgrade step A
                        ...
                        unit upgrade step Z
                post-upgrade steps
            ...
            availability zone N
                ...
    data-plane non-hypervisor principal applications upgrade
            application P
                ...
    data-plane subordinate applications upgrade
            application Q
                ...
    cloud post-upgrade steps
        (if ceph exists) Ensure correctness of 'require-osd-release' option in 'ceph-mon'
...

The above demonstrates a complete cloud upgrade plan. However, it’s also possible to target a specific subset of the cloud. For more information, please refer to Upgrade Groups.

The pre-upgrade steps prepare COU for the upgrade process, which includes verifying the states or configurations of the applications, units, or of the OpenStack cloud.

The upgrade steps are the main steps needed to run upgrades for each application.

The post-upgrade steps are responsible for making sure that the upgrade finishes successfully.

The plan can also be obtained without the need to perform a cloud upgrade using the plan command. See Plan an upgrade.

The Greek letter Psi Ψ indicates that the step and its sub-steps will run in parallel with other steps in the same level. In the example above, within the data-plane hypervisors upgrade, the unit 1 step will run in parallel with the unit K step, but their upgrade steps A to Z sub-steps will run sequentially.

Different upgrade strategies are chosen for control-plane and data-plane applications when preparing the plan. For details, please refer to Upgrade.