backend: Skip DaemonSet pods during drain

[harrshita123]

Summary

This PR fixes backend node drain behavior so DaemonSet-owned pods are skipped even when they do not have the legacy kubernetes.io/created-by=daemonset-controller label.

Related Issue

Fixes #5687

Changes

• Added DaemonSet pod detection using pod owner references.
• Kept the existing legacy label check for compatibility.
• Updated drain-node tests to verify DaemonSet-owned pods are not deleted.

Steps to Test

1. Run cd backend && go test ./cmd -run 'TestDrainNodePodDeletionFailure|TestDrainNodeAllPodsDeletedSuccessfully'.
2. Run cd backend && go test ./cmd.
3. Run npm run backend:lint.

Screenshots (if applicable)

Not applicable. This is a backend node drain change.

Notes for the Reviewer

The change is limited to the backend drain loop. It does not change how regular pods are deleted during drain; it only avoids deleting pods owned by DaemonSets.

[Copilot]

Pull request overview

This PR updates the backend node drain logic to correctly skip DaemonSet-owned pods by detecting DaemonSet ownership via pod ownerReferences (while retaining the legacy kubernetes.io/created-by=daemonset-controller label check), aligning Headlamp’s drain behavior with modern Kubernetes semantics.

Changes:

• Added isDaemonSetPod helper to identify DaemonSet pods via legacy label and ownerReferences.kind == "DaemonSet".
• Updated drainNode to use the helper to skip DaemonSet pods during deletion.
• Extended drain tests to validate deletion behavior and introduced a helper to extract deleted pod names from fake client actions.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
backend/cmd/headlamp.go	Adds DaemonSet pod detection helper and uses it to skip DaemonSet pods during node drain.
backend/cmd/headlamp_test.go	Updates drain tests and adds a helper to assert which pods were deleted.

[illume]

Thanks for the contribution.

There are some open Copilot review comments — could you take a look at them? Please mark each one as resolved once you've addressed it.

[harrshita123]

Thanks for the contribution.

There are some open Copilot review comments — could you take a look at them? Please mark each one as resolved once you've addressed it.

@illume
I resolved all the comments of copilot .

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[illume]

🎉 thanks!

[illume]

Sorry, noticed these two functions are missing some documentation. Could you please add it?

[k8s-ci-robot]

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This pull-request has been approved by: harrshita123
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[harrshita123]

Sorry, noticed these two functions are missing some documentation. Could you please add it?

Yeah sure .

[harrshita123]

@illume Added docs for both helper functions and force-pushed the branch as a single commit: backend: Skip DaemonSet pods during drain. I also reran the targeted backend tests:\n\ncd backend && go test ./cmd -run 'TestDrainNodePodDeletionFailure|TestDrainNodeAllPodsDeletedSuccessfully'\n\nResult: passed.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.