Files
actions-runner-controller/controllers/actions.github.com
Nikola JokicandCopilot App dd1e877f9e Confirm the finished runner cleanup marker outside the cache before scaling up
The scale-up suppression read Status.FinishedRunnerCleanupPatchID off the
EphemeralRunnerSet that Reconcile fetched through the manager's cached
client. That marker is written by the cleanup reconcile, and it is the
runner deletions performed by that same reconcile which trigger the next
one, so the follow-up reconcile is regularly served from an informer cache
that has not yet observed the controller's own status write. The marker
read as 0, the guard did not fire, and the controller created a
replacement runner for a job that had already finished. That is the exact
spurious scale up the guard exists to prevent, so it is a correctness
problem in a cluster and not only a flaky test.

Make the decision from authoritative state. A cached hit still short
circuits, because nothing ever clears the marker, so a hit cannot be a
false positive. Only a miss falls through to an uncached Get via a new
APIReader, which SetupWithManager fills in from mgr.GetAPIReader() so no
construction site can forget it. The extra read is confined to scale-up
decisions, where the controller is about to issue creates anyway.

The window was transient: updateStatus copies the marker from the
in-memory object and patches with MergeFrom, so a stale reconcile produces
no diff for that field and cannot clobber the recorded value.

The envtest spec that caught this only fails under CI load, so the
regression is pinned down directly instead. TestScaleUpServicedByFinished
RunnerCleanup drives the decision with a lagging cached client and an API
reader that already has the write, and asserts the suppression still
holds. Pointing the read back at the cached client fails that case and
only that case.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
2026-09-10 22:56:48 +02:00
..