serving Add support for GRPC probes

/area API /kind spec

Describe the feature

This is in alpha in K8s 1.23. https://twitter.com/ahmetb/status/1471530310072475655

Not sure if we fully switched to startupProbe, but this will let us route GRPC probes through the queue-proxy which is something we couldn't easily do with the execProbe path.

cc @dprotaso @julz

Dec 16 '21 18:12 mattmoor

This issue is stale because it has been open for 90 days with no activity. It will automatically close after 30 more days of inactivity. Reopen the issue with /reopen. Mark the issue as fresh by adding the comment /remove-lifecycle stale.

Mar 17 '22 01:03 github-actions[bot]

/remove-lifecycle stale

Mar 17 '22 01:03 psschwei

/lifecycle frozen

Mar 17 '22 01:03 mattmoor

:eyes: Kubernetes v1.24 [beta] supports GRPC probes

Mar 29 '23 15:03 FedirAlifirenko

Hello, I would like to use grpc probe in the knative service. But, it seems that it is not available because validateProbe does not allow grpc at this time.

https://github.com/knative/serving/blob/921daf867a3c598246836bcd2f9451ccdc10b0d0/pkg/apis/serving/k8s_validation.go#L804-L843

Do you have any concerns about applying grpc probe other than adding it to validateProbe?

Jun 20 '23 07:06 seongpyoHong

Hey @seongpyoHong it's a bit more complex because our queue proxy sidecar performs the probing in lieu of Kubernetes. This way we're able to poll more frequently than Kubernetes allows and can signal readiness faster.

Because of this I would recommend we go through the feature track process defined here - https://github.com/knative/community/blob/main/mechanics/FEATURE-TRACKS.md and write up a document that talks about how we'll introduce this feature and it's implications.

Jun 20 '23 13:06 dprotaso

I'm going to add this to the 1.12 Milestone (October) - this would be great if someone could pick it up

Jun 20 '23 13:06 dprotaso