fix(k8s): tolerate scale-to-zero during deployment readiness

[Elvand-Lie]

KEDA can scale a Deployment to zero while func waits after redeploy. The wait previously aborted when no active ReplicaSet supplied a pod-template-hash. Judge zero replicas by current-generation Deployment status, and retry inconsistent Deployment/ReplicaSet reads during scaling. API errors still fail and unresolved state still times out.

Idle zero-replica success does not establish that a pod of the new image ran. This changes the shared raw/keda wait; Knative uses its own Serving readiness. Remote deployments receive it after the func-util image is released.

Testing: exported wait and selector tests use a concrete Clientset with an httptest API server. They cover reconciled zero, stale/remaining status, scale-down between reads, healthy nonzero, timeout, cancellation and API errors. Main fails the reported hash-error regressions. Linux make test, make check, check-schema and check-embedded-fs passed. No valid revised Windows, live KEDA/cluster or macOS checks.

/kind bug
Fixes #4068

Raw and KEDA deployment readiness waits tolerate scale-to-zero and transient ReplicaSet changes instead of aborting on a missing pod-template-hash.

N/A

[knative-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: Elvand-Lie
Once this PR has been reviewed and has the lgtm label, please assign gauron99 for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[knative-prow]

Hi @Elvand-Lie. Thanks for your PR.

I'm waiting for a knative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

Tip

We noticed you've done this a few times! Consider joining the org to skip this step and gain /lgtm and other bot rights. We recommend asking approvers on your previous PRs to sponsor you.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.