Built-in Tekton PipelineRun Support

[adambkaplan]

What would you like to be added:

Support Tekton Pipelines as a built-in Kueue integration. Tekton PipelineRun objects can be potentially supported because it has a "suspended" equivalent through the Pending PipelineRun feature.

Why is this needed:

At scale, Tekton PipelineRun objects can overwhelm a Kubernetes cluster due to the chain of objects it creates (child TaskRun objects + Pods). Even with pruning mechanisms in place, a cluster that uses webhooks or other mechanisms to launch Tekton PipelineRuns can lead to cluster failure.

This is split out from #74, which also includes Argo Workflows. The latter is a different project with an entirely different set of APIs.

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[kannon92]

This sounds great! I wrote up a external integration here using pod integration.

It would probably be best to have someone from the tekton community to lead this implementation with a KEP. I'm not sure how many folks in the Kueue community are familar with Tekton.

[vdemeester]

@kannon92 you are right, I think someone from the Tekton Community should definitely help / drive this. This will require a KEP right ?

[kannon92]

I'm not sure actually. @mimowo @tenzen-y WDYT? Can we add an integration for Tekton without a KEP?

I'd prefer to see some kind of KEP to at least document the plan but I'll leave that decision to @tenzen-y and @mimowo.

It would also be worth seeing how this work would play with #74 as the hope was to have a general solution for workflows in Kueue.

[mimowo]

Can we add an integration for Tekton without a KEP?

Historically we added some integrations without KEP, but this is always tricky.

Plus, we don't have much expertise in Tekton so the KEP will be very much appreciated in this case to also describe the higher-level ideas.

[tenzen-y]

I also think that KEP would be better since in case of workflow supporting, it is obviously required to prepare additional mechanism similar to ArgoWorkflow supporting KEP

[gbenhaim]

Does the integration with Tekton should be added to kueue''s code base? I think that an external integration would be better.

[mimowo]

Staring externally is even better as Appswrapper started, or incubate it in kueue under cmd/experimental

[gbenhaim]

I created a simple external integration of Kueue and Tekton for supporting PipelineRuns. It's very basic but I think it provide a POC. You can find the code in https://github.com/konflux-ci/tekton-kueue and a short demo in https://www.youtube.com/watch?v=ppXd38CEhoE