Merge pull request #21149 from mwielgus/hpa-rescale

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pkg/controller/podautoscaler/horizontal.go

@@ -161,7 +161,6 @@ func (a *HorizontalController) computeReplicasForCustomMetrics(hpa extensions.Ho
 	}
 
 	return replicas, string(byteStatusList), timestamp, nil
-
 }
 
 func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodAutoscaler) error {
@@ -182,6 +181,18 @@ func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodA
 	cmStatus := ""
 	cmTimestamp := time.Time{}
 
+	desiredReplicas := 0
+	timestamp := time.Now()
+
+	if currentReplicas > hpa.Spec.MaxReplicas {
+		desiredReplicas = hpa.Spec.MaxReplicas
+	} else if hpa.Spec.MinReplicas != nil && currentReplicas < *hpa.Spec.MinReplicas {
+		desiredReplicas = *hpa.Spec.MinReplicas
+	} else if currentReplicas == 0 {
+		desiredReplicas = 1
+	} else {
+		// All basic scenarios covered, the state should be sane, lets use metrics.
+
 		if hpa.Spec.CPUUtilization != nil {
 			cpuDesiredReplicas, cpuCurrentUtilization, cpuTimestamp, err = a.computeReplicasForCPUUtilization(hpa, scale)
 			if err != nil {
@@ -198,9 +209,6 @@ func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodA
 			}
 		}
 
-	desiredReplicas := 0
-	timestamp := time.Time{}
-
 		if cpuDesiredReplicas > desiredReplicas {
 			desiredReplicas = cpuDesiredReplicas
 			timestamp = cpuTimestamp
@@ -222,6 +230,7 @@ func (a *HorizontalController) reconcileAutoscaler(hpa extensions.HorizontalPodA
 		if desiredReplicas > hpa.Spec.MaxReplicas {
 			desiredReplicas = hpa.Spec.MaxReplicas
 		}
+	}
 	rescale := false
 
 	if desiredReplicas != currentReplicas {

pkg/controller/podautoscaler/horizontal_test.go

@@ -333,6 +333,45 @@ func TestMinReplicas(t *testing.T) {
 	tc.runTest(t)
 }
 
+func TestZeroReplicas(t *testing.T) {
+	tc := testCase{
+		minReplicas:         3,
+		maxReplicas:         5,
+		initialReplicas:     0,
+		desiredReplicas:     3,
+		CPUTarget:           90,
+		reportedLevels:      []uint64{},
+		reportedCPURequests: []resource.Quantity{},
+	}
+	tc.runTest(t)
+}
+
+func TestToFewReplicas(t *testing.T) {
+	tc := testCase{
+		minReplicas:         3,
+		maxReplicas:         5,
+		initialReplicas:     2,
+		desiredReplicas:     3,
+		CPUTarget:           90,
+		reportedLevels:      []uint64{},
+		reportedCPURequests: []resource.Quantity{},
+	}
+	tc.runTest(t)
+}
+
+func TestTooManyReplicas(t *testing.T) {
+	tc := testCase{
+		minReplicas:         3,
+		maxReplicas:         5,
+		initialReplicas:     10,
+		desiredReplicas:     5,
+		CPUTarget:           90,
+		reportedLevels:      []uint64{},
+		reportedCPURequests: []resource.Quantity{},
+	}
+	tc.runTest(t)
+}
+
 func TestMaxReplicas(t *testing.T) {
 	tc := testCase{
 		minReplicas:         2,