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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
```
pull/6/head
Kubernetes Submit Queue 2017-07-17 13:23:47 -07:00 committed by GitHub
parent 12ba9bdc8c a99d988e3b
commit aed912bf63
2 changed files with 23 additions and 4 deletions
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8
pkg/controller/podautoscaler/horizontal.go
View File

@ -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")

19
pkg/controller/podautoscaler/horizontal_test.go
View File

@ -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,