kubernetes · omerap12 · May 29, 2025 · May 31, 2025 · May 31, 2025 · May 31, 2025
diff --git a/api/openapi-spec/swagger.json b/api/openapi-spec/swagger.json
diff --git a/api/openapi-spec/v3/apis__autoscaling__v2_openapi.json b/api/openapi-spec/v3/apis__autoscaling__v2_openapi.json
diff --git a/cmd/kube-controller-manager/app/autoscaling.go b/cmd/kube-controller-manager/app/autoscaling.go
@@ -75,6 +75,10 @@ func startHPAControllerWithMetricsClient(ctx context.Context, controllerContext
 	if err != nil {
 		return nil, false, err
 	}
+	dynamicClient, err := dynamic.NewForConfig(hpaClientConfig)
+	if err != nil {
+		return nil, false, err
+	}
 
 	go podautoscaler.NewHorizontalController(
 		ctx,
@@ -90,6 +94,7 @@ func startHPAControllerWithMetricsClient(ctx context.Context, controllerContext
 		controllerContext.ComponentConfig.HPAController.HorizontalPodAutoscalerTolerance,
 		controllerContext.ComponentConfig.HPAController.HorizontalPodAutoscalerCPUInitializationPeriod.Duration,
 		controllerContext.ComponentConfig.HPAController.HorizontalPodAutoscalerInitialReadinessDelay.Duration,
+		dynamicClient,
 	).Run(ctx, int(controllerContext.ComponentConfig.HPAController.ConcurrentHorizontalPodAutoscalerSyncs))
 	return nil, true, nil
 }
diff --git a/pkg/apis/autoscaling/annotations.go b/pkg/apis/autoscaling/annotations.go
@@ -44,3 +44,7 @@ const ToleranceScaleDownAnnotation = "autoscaling.alpha.kubernetes.io/scale-down
 // ToleranceScaleUpAnnotation is the annotation which holds the HPA tolerance specs
 // when converting the `ScaleUp.Tolerance` field from autoscaling/v2
 const ToleranceScaleUpAnnotation = "autoscaling.alpha.kubernetes.io/scale-up-tolerance"
+
+// SelectionStrategyAnnotation is the annotation which holds the pod selection strategy
+// when converting the `PodSelectionStrategy` field from autoscaling/v2
+const SelectionStrategyAnnotation = "autoscaling.alpha.kubernetes.io/pod-selection-strategy"
diff --git a/pkg/apis/autoscaling/helpers.go b/pkg/apis/autoscaling/helpers.go
@@ -40,16 +40,23 @@ func DropRoundTripHorizontalPodAutoscalerAnnotations(in map[string]string) (out
 	_, hasToleranceScaleUp := in[ToleranceScaleUpAnnotation]
 	_, hasMetricsStatuses := in[MetricStatusesAnnotation]
 	_, hasConditions := in[HorizontalPodAutoscalerConditionsAnnotation]
-	if hasMetricsSpecs || hasBehaviorSpecs || hasToleranceScaleDown || hasToleranceScaleUp || hasMetricsStatuses || hasConditions {
+	_, hasSelectionStrategy := in[SelectionStrategyAnnotation]
+
+	if hasMetricsSpecs || hasBehaviorSpecs || hasToleranceScaleDown ||
+		hasToleranceScaleUp || hasMetricsStatuses || hasConditions ||
+		hasSelectionStrategy {
+
 		out = DeepCopyStringMap(in)
 		delete(out, MetricSpecsAnnotation)
 		delete(out, BehaviorSpecsAnnotation)
 		delete(out, ToleranceScaleDownAnnotation)
 		delete(out, ToleranceScaleUpAnnotation)
 		delete(out, MetricStatusesAnnotation)
 		delete(out, HorizontalPodAutoscalerConditionsAnnotation)
+		delete(out, SelectionStrategyAnnotation)
 		return out, true
 	}
+
 	return in, false
 }
 

diff --git a/pkg/apis/autoscaling/types.go b/pkg/apis/autoscaling/types.go
@@ -73,6 +73,17 @@ type CrossVersionObjectReference struct {
 	APIVersion string
 }
 
+// SelectionStrategy defines how pods are selected for metrics collection and scaling decisions
+type SelectionStrategy string
+
+const (
+	// LabelSelector selects pods based on the label selector specified in the HPA's scale target
+	LabelSelector SelectionStrategy = "LabelSelector"
+
+	// OwnerReferences selects pods based on the ownership chain to the HPA's scale target
+	OwnerReferences SelectionStrategy = "OwnerReferences"
+)
+
 // HorizontalPodAutoscalerSpec describes the desired functionality of the HorizontalPodAutoscaler.
 type HorizontalPodAutoscalerSpec struct {
 	// scaleTargetRef points to the target resource to scale, and is used to the pods for which metrics
@@ -106,6 +117,25 @@ type HorizontalPodAutoscalerSpec struct {
 	// If not set, the default HPAScalingRules for scale up and scale down are used.
 	// +optional
 	Behavior *HorizontalPodAutoscalerBehavior
+
+	// SelectionStrategy determines how pods are selected for metrics collection
+	// and scaling decisions. Valid values are:
+	// - "LabelSelector": uses the label selector from the scale target (default)
+	// - "OwnerReferences": only considers pods owned by the scale target
+	//
+	// If not set, the default value "LabelSelector" is used, which maintains
+	// backward compatibility with existing behavior.
+	//
+	// For example, when using "OwnerReferences" with a Deployment target,
+	// only pods directly owned by the Deployment's ReplicaSets will be considered,
+	// even if other pods match the label selector.
+	//
+	// This is an alpha field and requires enabling the HPASelectionStrategy
+	// feature gate.
+	//
+	// +featureGate=HPASelectionStrategy
+	// +optional
+	SelectionStrategy *SelectionStrategy
 }
 
 // HorizontalPodAutoscalerBehavior configures a scaling behavior for Up and Down direction

diff --git a/pkg/apis/autoscaling/v1/conversion.go b/pkg/apis/autoscaling/v1/conversion.go
@@ -355,6 +355,19 @@ func Convert_autoscaling_HorizontalPodAutoscaler_To_v1_HorizontalPodAutoscaler(i
 		out.Annotations[autoscaling.BehaviorSpecsAnnotation] = string(behaviorEnc)
 	}
 
+	if in.Spec.SelectionStrategy != nil {
+		selectionStrategyEnc, err := json.Marshal(in.Spec.SelectionStrategy)
+		if err != nil {
+			return err
+		}
+		// copy before mutating
+		if !copiedAnnotations {
+			copiedAnnotations = true
+			out.Annotations = autoscaling.DeepCopyStringMap(out.Annotations)
+		}
+		out.Annotations[autoscaling.SelectionStrategyAnnotation] = string(selectionStrategyEnc)
+	}
+
 	if len(in.Status.Conditions) > 0 {
 		currentConditionsEnc, err := json.Marshal(currentConditions)
 		if err != nil {

diff --git a/pkg/apis/autoscaling/v1/zz_generated.conversion.go b/pkg/apis/autoscaling/v1/zz_generated.conversion.go
diff --git a/pkg/apis/autoscaling/v2/zz_generated.conversion.go b/pkg/apis/autoscaling/v2/zz_generated.conversion.go
diff --git a/pkg/apis/autoscaling/v2beta1/zz_generated.conversion.go b/pkg/apis/autoscaling/v2beta1/zz_generated.conversion.go
diff --git a/pkg/apis/autoscaling/v2beta2/conversion.go b/pkg/apis/autoscaling/v2beta2/conversion.go
@@ -34,6 +34,14 @@ func Convert_autoscaling_HorizontalPodAutoscaler_To_v2beta2_HorizontalPodAutosca
 	annotations, copiedAnnotations := autoscaling.DropRoundTripHorizontalPodAutoscalerAnnotations(out.Annotations)
 	out.Annotations = annotations
 
+	if in.Spec.SelectionStrategy != nil {
+		if !copiedAnnotations {
+			copiedAnnotations = true
+			out.Annotations = autoscaling.DeepCopyStringMap(out.Annotations)
+		}
+		out.Annotations[autoscaling.SelectionStrategyAnnotation] = string(*in.Spec.SelectionStrategy)
+	}
+
 	behavior := in.Spec.Behavior
 	if behavior == nil {
 		return nil
@@ -87,6 +95,11 @@ func Convert_v2beta2_HorizontalPodAutoscaler_To_autoscaling_HorizontalPodAutosca
 		}
 		out.Spec.Behavior.ScaleUp.Tolerance = &q
 	}
+
+	if strategyStr, ok := out.Annotations[autoscaling.SelectionStrategyAnnotation]; ok {
+		strategy := autoscaling.SelectionStrategy(strategyStr)
+		out.Spec.SelectionStrategy = &strategy
+	}
 	// Do not save round-trip annotations in internal resource
 	out.Annotations, _ = autoscaling.DropRoundTripHorizontalPodAutoscalerAnnotations(out.Annotations)
 	return nil
@@ -101,3 +114,19 @@ func Convert_autoscaling_HPAScalingRules_To_v2beta2_HPAScalingRules(in *autoscal
 	// Tolerance field is handled in the HorizontalPodAutoscaler conversion function.
 	return autoConvert_autoscaling_HPAScalingRules_To_v2beta2_HPAScalingRules(in, out, s)
 }
+
+func Convert_autoscaling_HorizontalPodAutoscalerSpec_To_v2beta2_HorizontalPodAutoscalerSpec(in *autoscaling.HorizontalPodAutoscalerSpec, out *autoscalingv2beta2.HorizontalPodAutoscalerSpec, s conversion.Scope) error {
+	if err := autoConvert_autoscaling_HorizontalPodAutoscalerSpec_To_v2beta2_HorizontalPodAutoscalerSpec(in, out, s); err != nil {
+		return err
+	}
+	// SelectionStrategy is handled in the HorizontalPodAutoscaler conversion function
+	return nil
+}
+
+func Convert_autoscaling_HorizontalPodAutoscalerStatus_To_v2beta2_HorizontalPodAutoscalerStatus(in *autoscaling.HorizontalPodAutoscalerStatus, out *autoscalingv2beta2.HorizontalPodAutoscalerStatus, s conversion.Scope) error {
+	if err := autoConvert_autoscaling_HorizontalPodAutoscalerStatus_To_v2beta2_HorizontalPodAutoscalerStatus(in, out, s); err != nil {
+		return err
+	}
+	// CurrentSelectionStrategy is handled in the HorizontalPodAutoscaler conversion function
+	return nil
+}
diff --git a/pkg/apis/autoscaling/v2beta2/zz_generated.conversion.go b/pkg/apis/autoscaling/v2beta2/zz_generated.conversion.go
diff --git a/pkg/apis/autoscaling/validation/validation.go b/pkg/apis/autoscaling/validation/validation.go
@@ -18,6 +18,7 @@ package validation
 
 import (
 	"fmt"
+	"slices"
 
 	apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
 	pathvalidation "k8s.io/apimachinery/pkg/api/validation/path"
@@ -73,6 +74,10 @@ func validateHorizontalPodAutoscalerSpec(autoscaler autoscaling.HorizontalPodAut
 	if refErrs := validateBehavior(autoscaler.Behavior, fldPath.Child("behavior"), opts); len(refErrs) > 0 {
 		allErrs = append(allErrs, refErrs...)
 	}
+	if refErrs := valdidateSelectionStrategy(autoscaler.SelectionStrategy, fldPath.Child("selectionStrategy"), opts); len(refErrs) > 0 {
+		allErrs = append(allErrs, refErrs...)
+	}
+
 	return allErrs
 }
 
@@ -172,6 +177,24 @@ func validateBehavior(behavior *autoscaling.HorizontalPodAutoscalerBehavior, fld
 	return allErrs
 }
 
+func valdidateSelectionStrategy(selectionStrategy *autoscaling.SelectionStrategy, fldPath *field.Path, opts HorizontalPodAutoscalerSpecValidationOptions) field.ErrorList {
+	allErrs := field.ErrorList{}
+	if selectionStrategy == nil {
+		return allErrs
+	}
+
+	supportedSelectionStrategy := []autoscaling.SelectionStrategy{
+		autoscaling.LabelSelector,
+		autoscaling.OwnerReferences,
+	}
+
+	if !slices.Contains(supportedSelectionStrategy, *selectionStrategy) {
+		allErrs = append(allErrs, field.NotSupported(field.NewPath("spec").Child("selectionStrategy"), *selectionStrategy, supportedSelectionStrategy))
+	}
+
+	return allErrs
+}
+
 var validSelectPolicyTypes = sets.NewString(string(autoscaling.MaxPolicySelect), string(autoscaling.MinPolicySelect), string(autoscaling.DisabledPolicySelect))
 var validSelectPolicyTypesList = validSelectPolicyTypes.List()
 

diff --git a/pkg/apis/autoscaling/zz_generated.deepcopy.go b/pkg/apis/autoscaling/zz_generated.deepcopy.go