instancetype: Add ControllerRevision upgrade proposal

lyarwood commented 2 months ago

What this PR does / why we need it:

VirtualMachines referencing instance types or preferences have ControllerRevisions created containing a point in time copy of the referenced resource. See the user guide for more on this:

https://kubevirt.io/user-guide/virtual_machines/instancetypes/#versioning

While this allows KubeVirt to always produce the same VirtualMachineInstance at run time regardless of changes to the original resource it does currently mean that KubeVirt has to support older versions of the instancetype.kubevirt.io CRDs for the lifetime of these VirtualMachines.

This proposal outlines a solution to this by upgrading older ControllerRevisions during a VirtualMachine resync by the vm-controller.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #

Special notes for your reviewer:

The original design proposal is here: https://github.com/kubevirt/community/pull/226

An old WIP series (drafted before sick leave) is here : https://github.com/kubevirt/kubevirt/pull/10545

Checklist

This checklist is not enforcing, but it's a reminder of items that could be relevant to every PR. Approvers are expected to review this list.

[ ] Design: A design document was considered and is present (link) or not required
[ ] PR: The PR description is expressive enough and will help future contributors
[ ] Code: Write code that humans can understand and Keep it simple
[ ] Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
[ ] Upgrade: Impact of this change on upgrade flows was considered and addressed if required
[ ] Testing: New code requires new unit tests. New features and bug fixes require at least on e2e test
[ ] Documentation: A user-guide update was considered and is present (link) or not required. You want a user-guide update if it's a user facing feature / API change.
[ ] Community: Announcement to kubevirt-dev was considered

Release note:

NONE

kubevirt-bot commented 2 months ago

Skipping CI for Draft Pull Request. If you want CI signal for your change, please convert it to an actual PR. You can still manually trigger a test run with /test all

kubevirt-bot commented 2 months ago

[APPROVALNOTIFIER] This PR is NOT APPROVED

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kubevirt / community

instancetype: Add ControllerRevision upgrade proposal #289