Merge remote-tracking branch 'origin/nikola-jokic-ers-scale-up-after-cleanup' into nikola-jokic-remove-integrity-hash-annotation

controllers/actions.github.com/ephemeralrunnerset_cleanup_patch_test.go

@@ -100,6 +100,54 @@ func TestPatchFinishedRunnerCleanupPatchIDStatusUsesOptimisticLock(t *testing.T)
 	assert.Equal(t, 4, updated.Status.FinishedRunnerCleanupPatchID)
 }
 
+// TestPatchFinishedRunnerCleanupPatchIDStatusRecordsALowerPatchID pins the
+// equality check against being "tidied" into the >= monotonicity check its
+// neighbour uses.
+//
+// Applied revisions come from metadata.generation and only climb, but listener
+// patch IDs do not: the scaler publishes 0 whenever the set is idle at
+// MinRunners with nothing dirty, restarts its sequence from 0 on a listener
+// restart, and wraps explicitly at math.MaxInt32. A marker that refused to move
+// down would sit above every value the listener subsequently publishes, and
+// because the scale-up guard suppresses only on an exact match, suppression
+// would never fire again.
+func TestPatchFinishedRunnerCleanupPatchIDStatusRecordsALowerPatchID(t *testing.T) {
+	scheme := runtime.NewScheme()
+	require.NoError(t, clientgoscheme.AddToScheme(scheme))
+	require.NoError(t, v1alpha1.AddToScheme(scheme))
+
+	ephemeralRunnerSet := &v1alpha1.EphemeralRunnerSet{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      "test-ers",
+			Namespace: "default",
+		},
+		Status: v1alpha1.EphemeralRunnerSetStatus{
+			FinishedRunnerCleanupPatchID: 7,
+		},
+	}
+
+	c := fake.NewClientBuilder().
+		WithScheme(scheme).
+		WithObjects(ephemeralRunnerSet).
+		WithStatusSubresource(&v1alpha1.EphemeralRunnerSet{}).
+		Build()
+
+	reconciler := &EphemeralRunnerSetReconciler{
+		Client:    c,
+		APIReader: c,
+		Log:       logr.Discard(),
+		Scheme:    scheme,
+	}
+
+	key := types.NamespacedName{Namespace: ephemeralRunnerSet.Namespace, Name: ephemeralRunnerSet.Name}
+	require.NoError(t, reconciler.patchFinishedRunnerCleanupPatchIDStatus(context.Background(), key, 1))
+
+	var updated v1alpha1.EphemeralRunnerSet
+	require.NoError(t, c.Get(context.Background(), key, &updated))
+	assert.Equal(t, 1, updated.Status.FinishedRunnerCleanupPatchID,
+		"a restarted or collapsed patch sequence must be recorded, or suppression can never match Spec.PatchID again")
+}
+
 // TestPatchFinishedRunnerCleanupPatchIDStatusIsIdempotent covers the early
 // return: a marker already recording this patch ID must not be rewritten, so
 // repeated reconciles for one patch do not churn the status.

controllers/actions.github.com/ephemeralrunnerset_controller.go

@@ -417,6 +417,24 @@ func (r *EphemeralRunnerSetReconciler) scaleUpServicedByFinishedRunnerCleanup(ct
 // read and the patch rather than closing it, because the decision is only as
 // fresh as the moment it was taken. The lock is what makes the write conditional
 // on that decision still holding.
+//
+// The check below is deliberately an equality test and must not be relaxed into
+// the >= monotonicity test the applied revision uses. Applied revisions derive
+// from metadata.generation and only ever climb, but listener patch IDs do not:
+// setDesiredWorkerState publishes 0 whenever the set is idle at MinRunners with
+// nothing dirty, restarts its sequence from 0 when the listener restarts, and
+// wraps explicitly at math.MaxInt32. So Spec.PatchID legitimately moves
+// backwards, and the marker has to follow it. Refusing to record a lower patch
+// ID would strand the marker above every value the listener goes on to publish,
+// and since the scale-up guard suppresses only on an exact match, suppression
+// would never fire again -- disabling the behaviour this layer exists to add.
+//
+// That is also why the lock is the right fix rather than a stricter comparison.
+// It cannot make an older patch ID unwritable, because the retry re-reads and
+// re-applies the same argument; recording the patch ID whose cleanup actually
+// happened is a true statement regardless of ordering, and the next cleanup
+// re-records. What the lock prevents is a write decided against state that has
+// since changed.
 func (r *EphemeralRunnerSetReconciler) patchFinishedRunnerCleanupPatchIDStatus(ctx context.Context, key types.NamespacedName, patchID int) error {
 	return retry.RetryOnConflict(retry.DefaultBackoff, func() error {
 		var latest v1alpha1.EphemeralRunnerSet