Epic Goal

Allow layered projects/products to easily integrate with multikueue for multicluster job support when used as an RHACM add-on. This would allow a way for Kueue to provide a way to use a custom CRD for job execution.

Why is this important?

Currently multikueue doesn't support external frameworks for job execution. Being able to support this would allow external projects to more easily be used for multicluster job execution whilst being able to retain control of their own releases and not have to manage the integration. For Kueue this would open up the usage to a more "plug and play" model.

For the RHBoK multicluster add-on provided by RHACM it would allow layered products to easily utilise multikueue in RHACM via the add-on.

Scenarios

An external project or layered product would like to use multikueue for multicluster job execution but does not want, or can not, maintain that integration. RHACM, and the RHBoK add-on can introduce this as a standard interface for adding a project to a multicluster environment.

Acceptance Criteria

The add-on provides a way to add external projects and provides a hook for custom CRDs in multikueue.

Dependencies (internal and external)

1. Functionality needs to be added to Kueue upstream  

Previous Work (Optional):

1. Upstream Kueue KEP: https://github.com/kubernetes-sigs/kueue/pull/2458
2. Similar/same upstream KEP: https://github.com/kubernetes-sigs/kueue/pull/5981 
3. Upstream Red Hat Tekton request to Kueue community and answer: https://github.com/kubernetes-sigs/kueue/issues/2349#issuecomment-3044109201 

Open questions:

1. Do we use OCM's manifestwork controller for this?

Done Checklist

• CI - CI is running, tests are automated and merged.
• Release Enablement <link to Feature Enablement Presentation>
• DEV - Upstream code and tests merged: <link to meaningful PR or GitHub
  Issue>
• DEV - Upstream documentation merged: <link to meaningful PR or GitHub
  Issue>
• DEV - Downstream build attached to advisory: <link to errata>
• QE - Test plans in Polarion: <link or reference to Polarion>
• QE - Automated tests merged: <link or reference to automated tests>
• DOC - Doc issue opened with a completed template. Separate doc issue
  opened for any deprecation, removal, or any current known
  issue/troubleshooting removal from the doc, if applicable.
• Considerations were made for Extended Update Support (EUS)