VPA updater: fix unready DaemonSet updates

[dippynark]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Currently if all DaemonSet Pods become not ready (for example, VPA scales memory limits down too low and they all start OOMing) then VPA cannot scale the Pods back up again due to the following error:

Failed to obtain replication info ... daemon set ... has no number ready pods

This is because we're looking at the wrong field in the DaemonSet status to determine the desired number of Pods. This PR fixes this by looking at daemonSet.Status.DesiredNumberScheduled instead of daemonSet.Status.NumberReady.

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

None

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

Summary by CodeRabbit

• Bug Fixes
  • Improved pod eviction decisions for DaemonSet-managed workloads by using the desired scheduled pod count.
  • Corrected behavior when DaemonSet pods are not yet ready, allowing eligible pods to be evaluated accurately.

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: dippynark
Once this PR has been reviewed and has the lgtm label, please assign omerap12 for approval. For more information see the Code Review Process.

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Details

Needs approval from an approver in each of these files:

• vertical-pod-autoscaler/OWNERS

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[kubernetes-prow]

This issue is currently awaiting triage.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 6a194abc-cf04-4df1-ab7e-74b4bee96bde

📥 Commits

Reviewing files that changed from the base of the PR and between 5e07dd5 and 1b5df75.

📒 Files selected for processing (2)

• vertical-pod-autoscaler/pkg/updater/restriction/pods_restriction_factory.go
• vertical-pod-autoscaler/pkg/updater/restriction/pods_restriction_factory_test.go

---

📝 Walkthrough

Walkthrough

The updater now bases DaemonSet replica restrictions on Status.DesiredNumberScheduled. Tests cover DaemonSets with all scheduled pods ready and with none ready.

Changes

DaemonSet replica count correction

Layer / File(s)	Summary
Scheduled count validation vertical-pod-autoscaler/pkg/updater/restriction/pods_restriction_factory.go, vertical-pod-autoscaler/pkg/updater/restriction/pods_restriction_factory_test.go	getReplicaCount uses DesiredNumberScheduled and reports zero scheduled replicas. Table-driven tests cover ready and unready DaemonSet pods and verify eviction limits.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 1b5df

This localized fix changes DaemonSet replica information used by VPA updates; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: adrianmoisey, maxcao13, omerap12

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the DaemonSet unready-Pod handling fix, which is the main change in the pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[kubernetes-prow]

Hi @dippynark. Thanks for your PR.

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[dippynark]

/kind bug