[nikola-jokic]

Release 0.15.1

Follows #4697. The release branch currently contains master through 0532c16b.

Release prerequisite: #4726 must merge into master before this release PR is merged/published. Refresh this branch after it merges; its changelog entry is included below, but its implementation is not yet on this branch.

Bumps version and appVersion to 0.15.1 in all four stable/experimental scale-set charts and adds the changelog and controller-only upgrade guidance.

1. Requeue rate-limited scale-set requests without client retries #4726
2. Remove succeeded ephemeral runners that never ran a job from the service #4709
3. Bump Go to 1.27.3 and update Go dependencies #4725
4. Updates: runner to v2.338.1 #4724
5. Updates: runner to v2.338.0 #4708
6. Fix inconsistent guards for scale set metrics registration and publishing #4566
7. Read the e2e Go version from go.mod and apply the safe go fix modernizers #4677

CRD upgrade compatibility

Existing 0.15.0 CRDs can remain installed when upgrading the controller to 0.15.1. A CRD update, replacement, or ARC resource recreation is not required.

Compared all four actions.github.com CRDs against the actual scale-set release tag, gha-runner-scale-set-0.15.0, and checked both stable and experimental controller chart copies against their generated bases. The only differences are:

• controller-gen.kubebuilder.io/version: v0.22.0 → v0.23.0.
• Generated validation on existing embedded Pod evictionResponders: names must be non-empty, priorities must be between 0 and 100000, and the list is limited to 10 entries.

No ARC fields, required fields, defaults, served/storage versions, conversion settings, or other schema content changed. ARC Go API types, controller chart templates, and generated controller RBAC are unchanged since 0.15.0. The controller therefore does not depend on installing the newly generated validation rules. If CRDs are explicitly updated separately, custom evictionResponders values must satisfy the tighter validation. The current #4726 diff does not modify CRDs or ARC API types.

Verification

• All three scale-set chart Go test packages passed.
• Helm lint passed for all four scale-set charts.
• Recursive parsed-YAML comparison allowed only the exact CRD differences above and verified all four chart versions.
• git diff --check passed; master CI checks at 0532c16b were successful.

These checks preceded integration of #4726; refresh and validate the release branch once that prerequisite merges.

No live-cluster upgrade was performed. The local Helm CLI is v4.0.5, rather than CI's v4.2.2, and the helm-unittest plugin is not installed; experimental Helm unit suites remain for CI. This PR prepares the release only; it does not publish images/charts or create release tags.

[Copilot]

🟢 Approval recommended

The changes are limited to consistent release metadata and documentation, with no unresolved blocking findings.

No open issues 🎉

What changed in this PR

Prepares ARC 0.15.1 by aligning the stable and experimental scale-set chart versions and documenting the release. This PR does not publish release artifacts.

Changes:

• Bumps version and appVersion to 0.15.1 in all four charts.
• Adds the release changelog covering runner cleanup, metrics fixes, and dependency updates.
• Documents that controller upgrades from 0.15.0 can retain existing CRDs without recreating ARC resources.

File	Description
docs/​gha-runner-scale-set-controller/​README.md	Adds the 0.15.1 changelog and CRD compatibility guidance.
charts/​gha-runner-scale-set/​Chart.yaml	Updates stable scale-set chart and application versions.
charts/​gha-runner-scale-set-experimental/​Chart.yaml	Updates experimental scale-set chart and application versions.
charts/​gha-runner-scale-set-controller/​Chart.yaml	Updates stable controller chart and application versions.
charts/​gha-runner-scale-set-controller-experimental/​Chart.yaml	Updates experimental controller chart and application versions.

_{Review effort: Balanced}

[salmanmkc]

🥳