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HPA scale-to-zero for custom object/external metrics

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Add support for scaling to zero pods

minReplicas is allowed to be zero

condition is set once

Based on https://github.com/kubernetes/kubernetes/pull/61423

set original valid condition

add scale to/from zero and invalid metric tests

Scaling up from zero pods ignores tolerance

validate metrics when minReplicas is 0

Document HPA behaviour when minReplicas is 0

Documented minReplicas field in autoscaling APIs
This commit is contained in:
Rinat Shigapov
2019-02-18 15:29:37 +00:00
parent 1bf7103ea0
commit d55f037b7d
10 changed files with 629 additions and 148 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
pkg/apis/autoscaling/validation/validation.go
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@@ -17,14 +17,17 @@ limitations under the License.
package validation
import (
"fmt"
"strings"
apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
pathvalidation "k8s.io/apimachinery/pkg/api/validation/path"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/apimachinery/pkg/util/validation/field"
utilfeature "k8s.io/apiserver/pkg/util/feature"
"k8s.io/kubernetes/pkg/apis/autoscaling"
apivalidation "k8s.io/kubernetes/pkg/apis/core/validation"
"k8s.io/kubernetes/pkg/features"
)
func ValidateScale(scale *autoscaling.Scale) field.ErrorList {
@@ -42,10 +45,12 @@ func ValidateScale(scale *autoscaling.Scale) field.ErrorList {
// Prefix indicates this name will be used as part of generation, in which case trailing dashes are allowed.
var ValidateHorizontalPodAutoscalerName = apivalidation.ValidateReplicationControllerName
func validateHorizontalPodAutoscalerSpec(autoscaler autoscaling.HorizontalPodAutoscalerSpec, fldPath *field.Path) field.ErrorList {
func validateHorizontalPodAutoscalerSpec(autoscaler autoscaling.HorizontalPodAutoscalerSpec, fldPath *field.Path, minReplicasLowerBound int32) field.ErrorList {
allErrs := field.ErrorList{}
if autoscaler.MinReplicas != nil && *autoscaler.MinReplicas < 1 {
allErrs = append(allErrs, field.Invalid(fldPath.Child("minReplicas"), *autoscaler.MinReplicas, "must be greater than 0"))
if autoscaler.MinReplicas != nil && *autoscaler.MinReplicas < minReplicasLowerBound {
allErrs = append(allErrs, field.Invalid(fldPath.Child("minReplicas"), *autoscaler.MinReplicas,
fmt.Sprintf("must be greater than or equal to %d", minReplicasLowerBound)))
}
if autoscaler.MaxReplicas < 1 {
allErrs = append(allErrs, field.Invalid(fldPath.Child("maxReplicas"), autoscaler.MaxReplicas, "must be greater than 0"))
@@ -56,7 +61,7 @@ func validateHorizontalPodAutoscalerSpec(autoscaler autoscaling.HorizontalPodAut
if refErrs := ValidateCrossVersionObjectReference(autoscaler.ScaleTargetRef, fldPath.Child("scaleTargetRef")); len(refErrs) > 0 {
allErrs = append(allErrs, refErrs...)
}
if refErrs := validateMetrics(autoscaler.Metrics, fldPath.Child("metrics")); len(refErrs) > 0 {
if refErrs := validateMetrics(autoscaler.Metrics, fldPath.Child("metrics"), autoscaler.MinReplicas); len(refErrs) > 0 {
allErrs = append(allErrs, refErrs...)
}
return allErrs
@@ -85,13 +90,34 @@ func ValidateCrossVersionObjectReference(ref autoscaling.CrossVersionObjectRefer
func ValidateHorizontalPodAutoscaler(autoscaler *autoscaling.HorizontalPodAutoscaler) field.ErrorList {
allErrs := apivalidation.ValidateObjectMeta(&autoscaler.ObjectMeta, true, ValidateHorizontalPodAutoscalerName, field.NewPath("metadata"))
allErrs = append(allErrs, validateHorizontalPodAutoscalerSpec(autoscaler.Spec, field.NewPath("spec"))...)
// MinReplicasLowerBound represents a minimum value for minReplicas
// 0 when HPA scale-to-zero feature is enabled
var minReplicasLowerBound int32
if utilfeature.DefaultFeatureGate.Enabled(features.HPAScaleToZero) {
minReplicasLowerBound = 0
} else {
minReplicasLowerBound = 1
}
allErrs = append(allErrs, validateHorizontalPodAutoscalerSpec(autoscaler.Spec, field.NewPath("spec"), minReplicasLowerBound)...)
return allErrs
}
func ValidateHorizontalPodAutoscalerUpdate(newAutoscaler, oldAutoscaler *autoscaling.HorizontalPodAutoscaler) field.ErrorList {
allErrs := apivalidation.ValidateObjectMetaUpdate(&newAutoscaler.ObjectMeta, &oldAutoscaler.ObjectMeta, field.NewPath("metadata"))
allErrs = append(allErrs, validateHorizontalPodAutoscalerSpec(newAutoscaler.Spec, field.NewPath("spec"))...)
// minReplicasLowerBound represents a minimum value for minReplicas
// 0 when HPA scale-to-zero feature is enabled or HPA object already has minReplicas=0
var minReplicasLowerBound int32
if utilfeature.DefaultFeatureGate.Enabled(features.HPAScaleToZero) || (oldAutoscaler.Spec.MinReplicas != nil && *oldAutoscaler.Spec.MinReplicas == 0) {
minReplicasLowerBound = 0
} else {
minReplicasLowerBound = 1
}
allErrs = append(allErrs, validateHorizontalPodAutoscalerSpec(newAutoscaler.Spec, field.NewPath("spec"), minReplicasLowerBound)...)
return allErrs
}
@@ -103,14 +129,28 @@ func ValidateHorizontalPodAutoscalerStatusUpdate(newAutoscaler, oldAutoscaler *a
return allErrs
}
func validateMetrics(metrics []autoscaling.MetricSpec, fldPath *field.Path) field.ErrorList {
func validateMetrics(metrics []autoscaling.MetricSpec, fldPath *field.Path, minReplicas *int32) field.ErrorList {
allErrs := field.ErrorList{}
hasObjectMetrics := false
hasExternalMetrics := false
for i, metricSpec := range metrics {
idxPath := fldPath.Index(i)
if targetErrs := validateMetricSpec(metricSpec, idxPath); len(targetErrs) > 0 {
allErrs = append(allErrs, targetErrs...)
}
if metricSpec.Type == autoscaling.ObjectMetricSourceType {
hasObjectMetrics = true
}
if metricSpec.Type == autoscaling.ExternalMetricSourceType {
hasExternalMetrics = true
}
}
if minReplicas != nil && *minReplicas == 0 {
if !hasObjectMetrics && !hasExternalMetrics {
allErrs = append(allErrs, field.Forbidden(fldPath, "must specify at least one Object or External metric to support scaling to zero replicas"))
}
}
return allErrs