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Merge pull request #48997 from johanneswuerbach/hpa-min

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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
```
This commit is contained in:
Kubernetes Submit Queue 2017-07-17 13:23:47 -07:00 committed by GitHub
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: case desiredReplicas > scaleUpLimit:
setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "ScaleUpLimit", "the desired replica count is increasing faster than the maximum scale rate") setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "ScaleUpLimit", "the desired replica count is increasing faster than the maximum scale rate")
desiredReplicas = scaleUpLimit 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: case hpa.Spec.MinReplicas != nil && desiredReplicas < *hpa.Spec.MinReplicas:
// make sure we aren't below our minimum // 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") setCondition(hpa, autoscalingv2.ScalingLimited, v1.ConditionTrue, "TooFewReplicas", "the desired replica count was less than the minimum replica count")
desiredReplicas = *hpa.Spec.MinReplicas 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: case desiredReplicas > hpa.Spec.MaxReplicas:
// make sure we aren't above our maximum // 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") 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) 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) { func TestZeroReplicas(t *testing.T) {
tc := testCase{ tc := testCase{
minReplicas: 3, minReplicas: 3,