Merge pull request #7997 from damikag/scale-down-slo-update-metric

Emit scale down metric even when there is no scale down candidates.

Author: k8s-ci-robot

cluster-autoscaler/core/scaledown/status/status.go

@@ -98,6 +98,8 @@ const (
 	ScaleDownInCooldown
 	// ScaleDownInProgress - the scale down wasn't attempted, because a previous scale-down was still in progress.
 	ScaleDownInProgress
+	// ScaleDownNoCandidates - the scale down was skipped because of no scale down candidates.
+	ScaleDownNoCandidates
 )
 
 // NodeDeleteResultType denotes the type of the result of node deletion. It provides deeper

cluster-autoscaler/core/static_autoscaler.go

@@ -606,7 +606,7 @@ func (a *StaticAutoscaler) RunOnce(currentTime time.Time) caerrors.AutoscalerErr
 
 		metrics.UpdateDurationFromStart(metrics.FindUnneeded, unneededStart)
 
-		scaleDownInCooldown := a.isScaleDownInCooldown(currentTime, scaleDownCandidates)
+		scaleDownInCooldown := a.isScaleDownInCooldown(currentTime)
 		klog.V(4).Infof("Scale down status: lastScaleUpTime=%s lastScaleDownDeleteTime=%v "+
 			"lastScaleDownFailTime=%s scaleDownForbidden=%v scaleDownInCooldown=%v",
 			a.lastScaleUpTime, a.lastScaleDownDeleteTime, a.lastScaleDownFailTime,
@@ -628,6 +628,11 @@ func (a *StaticAutoscaler) RunOnce(currentTime time.Time) caerrors.AutoscalerErr
 		if scaleDownInCooldown {
 			scaleDownStatus.Result = scaledownstatus.ScaleDownInCooldown
 			a.updateSoftDeletionTaints(allNodes)
+		} else if len(scaleDownCandidates) == 0 {
+			klog.V(4).Infof("Starting scale down: no scale down candidates. skipping...")
+			scaleDownStatus.Result = scaledownstatus.ScaleDownNoCandidates
+			metrics.UpdateLastTime(metrics.ScaleDown, time.Now())
+			a.updateSoftDeletionTaints(allNodes)
 		} else {
 			klog.V(4).Infof("Starting scale down")
 
@@ -712,8 +717,8 @@ func (a *StaticAutoscaler) addUpcomingNodesToClusterSnapshot(upcomingCounts map[
 	return nil
 }
 
-func (a *StaticAutoscaler) isScaleDownInCooldown(currentTime time.Time, scaleDownCandidates []*apiv1.Node) bool {
-	scaleDownInCooldown := a.processorCallbacks.disableScaleDownForLoop || len(scaleDownCandidates) == 0
+func (a *StaticAutoscaler) isScaleDownInCooldown(currentTime time.Time) bool {
+	scaleDownInCooldown := a.processorCallbacks.disableScaleDownForLoop
 
 	if a.ScaleDownDelayTypeLocal {
 		return scaleDownInCooldown