Merge pull request #48997 from johanneswuerbach/hpa-min

Automatic merge from submit-queue (batch tested with PRs 48997, 48595, 48898, 48711, 48972) hpa: Prevent scaling below MinReplicas if desiredReplicas is zero **What this PR does / why we need it**: Prevent a HPA scaling below `minReplicas` if `desiredReplicas` is calculated as `0`. Example events of a HPA continuously scaling between `1` and `MinReplicas`: ``` 2h 59s 22 horizontal-pod-autoscaler Normal SuccessfulRescale New size: 1; reason: All metrics below target 2h 29s 22 horizontal-pod-autoscaler Normal SuccessfulRescale New size: 15; reason: Current number of replicas below Spec.MinReplicas ``` **Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #49028 **Special notes for your reviewer**: **Release note**: ```release-note hpa: Prevent scaling below MinReplicas if desiredReplicas is zero ```

Merge pull request #48997 from johanneswuerbach/hpa-min
aed912bf · Kubernetes Submit Queue · GitHub · 12ba9bdc · a99d988e · aed912bf
Commit aed912bf authored Jul 17, 2017 by Kubernetes Submit Queue Committed by GitHub Jul 17, 2017
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Showing with 23 additions and 4 deletions

horizontal.go pkg/controller/podautoscaler/horizontal.go +4 -4

horizontal_test.go pkg/controller/podautoscaler/horizontal_test.go +19 -0

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--- a/pkg/controller/podautoscaler/horizontal.go
+++ b/pkg/controller/podautoscaler/horizontal.go
@@ -450,14 +450,14 @@ func (a *HorizontalController) reconcileAutoscaler(hpav1Shared *autoscalingv1.Ho
 		case desiredReplicas > scaleUpLimit:
 			setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "ScaleUpLimit", "the desired replica count is increasing faster than the maximum scale rate")
 			desiredReplicas = scaleUpLimit
-		case desiredReplicas == 0:
-			//  never scale down to 0, reserved for disabling autoscaling
-			setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "TooFewReplicas", "the desired replica count was zero")
-			desiredReplicas = 1
 		case hpa.Spec.MinReplicas != nil && desiredReplicas < *hpa.Spec.MinReplicas:
 			// make sure we aren't below our minimum
 			setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "TooFewReplicas", "the desired replica count was less than the minimum replica count")
 			desiredReplicas = *hpa.Spec.MinReplicas
+		case desiredReplicas == 0:
+			//  never scale down to 0, reserved for disabling autoscaling
+			setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "TooFewReplicas", "the desired replica count was zero")
+			desiredReplicas = 1
 		case desiredReplicas > hpa.Spec.MaxReplicas:
 			// make sure we aren't above our maximum
 			setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "TooManyReplicas", "the desired replica count was more than the maximum replica count")

--- a/pkg/controller/podautoscaler/horizontal_test.go
+++ b/pkg/controller/podautoscaler/horizontal_test.go
@@ -994,6 +994,25 @@ func TestMinReplicas(t *testing.T) {
 	tc.runTest(t)
 }

+func TestMinReplicasDesiredZero(t *testing.T) {
+	tc := testCase{
+		minReplicas:         2,
+		maxReplicas:         5,
+		initialReplicas:     3,
+		desiredReplicas:     2,
+		CPUTarget:           90,
+		reportedLevels:      []uint64{0, 0, 0},
+		reportedCPURequests: []resource.Quantity{resource.MustParse("0.9"), resource.MustParse("1.0"), resource.MustParse("1.1")},
+		useMetricsApi:       true,
+		expectedConditions: statusOkWithOverrides(autoscalingv2.HorizontalPodAutoscalerCondition{
+			Type:   autoscalingv2.ScalingLimited,
+			Status: v1.ConditionTrue,
+			Reason: "TooFewReplicas",
+		}),
+	}
+	tc.runTest(t)
+}
+
 func TestZeroReplicas(t *testing.T) {
 	tc := testCase{
 		minReplicas:         3,