Research :: Readiness Scheduling Gates

[thisthat]

Goal

Prototype a KLT implementation that uses Pod Scheduling Readiness instead of the Scheduling Plugin.

Technical Details

KLT currently uses a custom plugin for the scheduler to forbid Pods from being bound to a node. With the new addition of the Readiness Gates, we could eliminate the extra binary and use the new API. This has some consequences for our mutating webhook: it should add a gate when a manifest is applied (on update it won't). When the pre-checks are completed successfully, the gates shall be removed.

Resources

• Changelog: https://kubernetes.io/blog/2023/04/11/kubernetes-v1-27-release/#pod-scheduling-readiness-goes-to-beta

[thisthat]

Old PoC that used a workaround with extra labels: #632

[thisthat]

PR kubernetes-sigs/controller-runtime#2189 has been merged and unlocks this research