feat: allow custom metrics configuration of FederatedHPA

Signed-off-by: jwcesign <jwcesign@gmail.com>

pkg/util/lifted/corehelpers.go

@@ -24,8 +24,6 @@ import (
 	"strings"
 
 	corev1 "k8s.io/api/core/v1"
-	apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/validation"
 	"k8s.io/apimachinery/pkg/util/validation/field"
@@ -162,71 +160,3 @@ func ValidateDNS1123Label(value string, fldPath *field.Path) field.ErrorList {
 	}
 	return allErrs
 }
-
-// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/core/validation/validation.go
-
-// ValidateNameFunc validates that the provided name is valid for a given resource type.
-// Not all resources have the same validation rules for names. Prefix is true
-// if the name will have a value appended to it.  If the name is not valid,
-// this returns a list of descriptions of individual characteristics of the
-// value that were not valid.  Otherwise this returns an empty list or nil.
-type ValidateNameFunc apimachineryvalidation.ValidateNameFunc
-
-// ValidateObjectMeta validates an object's metadata on creation. It expects that name generation has already
-// been performed.
-// It doesn't return an error for rootscoped resources with namespace, because namespace should already be cleared before.
-// TODO: Remove calls to this method scattered in validations of specific resources, e.g., ValidatePodUpdate.
-func ValidateObjectMeta(meta *metav1.ObjectMeta, requiresNamespace bool, nameFn ValidateNameFunc, fldPath *field.Path) field.ErrorList {
-	allErrs := apimachineryvalidation.ValidateObjectMeta(meta, requiresNamespace, apimachineryvalidation.ValidateNameFunc(nameFn), fldPath)
-	// run additional checks for the finalizer name
-	for i := range meta.Finalizers {
-		allErrs = append(allErrs, validateKubeFinalizerName(string(meta.Finalizers[i]), fldPath.Child("finalizers").Index(i))...)
-	}
-	return allErrs
-}
-
-// validateKubeFinalizerName checks for "standard" names of legacy finalizer
-func validateKubeFinalizerName(stringValue string, fldPath *field.Path) field.ErrorList {
-	allErrs := field.ErrorList{}
-	if len(strings.Split(stringValue, "/")) == 1 {
-		if IsStandardFinalizerName(stringValue) {
-			return append(allErrs, field.Invalid(fldPath, stringValue, "name is neither a standard finalizer name nor is it fully qualified"))
-		}
-	}
-
-	return allErrs
-}
-
-// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/core/helper/helpers.go
-
-var standardFinalizers = sets.NewString(
-	string(corev1.FinalizerKubernetes),
-	metav1.FinalizerOrphanDependents,
-	metav1.FinalizerDeleteDependents,
-)
-
-// IsStandardFinalizerName checks if the input string is a standard finalizer name
-func IsStandardFinalizerName(str string) bool {
-	return standardFinalizers.Has(str)
-}
-
-// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/staging/src/k8s.io/apimachinery/pkg/api/validation/generic.go
-
-// NameIsDNSSubdomain is a ValidateNameFunc for names that must be a DNS subdomain.
-func NameIsDNSSubdomain(name string, prefix bool) []string {
-	if prefix {
-		name = maskTrailingDash(name)
-	}
-	return validation.IsDNS1123Subdomain(name)
-}
-
-// maskTrailingDash replaces the final character of a string with a subdomain safe
-// value if it is a dash and if the length of this string is greater than 1. Note that
-// this is used when a value could be appended to the string, see ValidateNameFunc
-// for more info.
-func maskTrailingDash(name string) string {
-	if len(name) > 1 && strings.HasSuffix(name, "-") {
-		return name[:len(name)-2] + "a"
-	}
-	return name
-}

pkg/util/lifted/doc.go

@@ -13,9 +13,6 @@ package lifted
 | corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/helper/helpers.go#L261-L264                                                          | func IsStandardResourceName                       | N       |
 | corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/helper/helpers.go#LL266-L276                                                         | var integerResources                              | Y       |
 | corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/helper/helpers.go#L278-L281                                                          | func IsIntegerResourceName                        | N       |
-| corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/core/validation/validation.go                                                             | type ValidateNameFunc                             | N       |
-| corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/core/helper/helpers.go                                                                    | var standardFinalizers                            | N       |
-| corehelpers.go           | https://github.com/kubernetes/kubernetes/blob/release-1.27/staging/src/k8s.io/apimachinery/pkg/api/validation/generic.go                                      | func NameIsDNSSubdomain                           | N       |
 | corev1helpers.go         | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/v1/helper/helpers.go#L31-L46                                                         | func IsExtendedResourceName                       | Y       |
 | corev1helpers.go         | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/v1/helper/helpers.go#L48-L51                                                         | func IsPrefixedNativeResource                     | N       |
 | corev1helpers.go         | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/v1/helper/helpers.go#L54-L60                                                         | func IsNativeResource                             | N       |
@@ -78,6 +75,26 @@ package lifted
 | taint_test.go            | https://github.com/kubernetes/kubernetes/blob/release-1.26/staging/src/k8s.io/kubectl/pkg/cmd/taint/utils_test.go#L372-L533                                   | func TestParseTaints                              | N       |
 | validateclustertaints.go | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/validation/validation.go#L3497-L3518                                                 | func validateClusterTaintEffect                   | Y       |
 | validateclustertaints.go | https://github.com/kubernetes/kubernetes/blob/release-1.26/pkg/apis/core/validation/validation.go#L5227-L5259                                                 | func ValidateClusterTaints                        | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L32-37                                               | const MaxPeriodSeconds                            | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L32-37                                               | const MaxStabilizationWindowSeconds               | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L103-L119                                            | func ValidateFederatedHPA                         | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L55-L78                                              | func validateFederatedHPASpec                     | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L80-L101                                             | func ValidateCrossVersionObjectReference          | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L140-L148                                            | func validateFederatedHPAStatus                   | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L150-L175                                            | func validateMetrics                              | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L177-L188                                            | func validateBehavior                             | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L190-L191                                            | var validSelectPolicyTypes                        | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L193-L218                                            | func validateScalingRules                         | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L220-L221                                            | var validPolicyTypes                              | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L223-L239                                            | func validateScalingPolicy                        | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L241-L245                                            | var validMetricSourceTypes                        | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L247-L339                                            | func validateMetricSpec                           | Y       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L340-L352                                            | func validateObjectSource                         | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L371-L382                                            | func validatePodsSource                           | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L383-L410                                            | func validateContainerResourceSource              | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L412-L430                                            | func validateResourceSource                       | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L432-L458                                            | func validateMetricTarget                         | N       |
+| validatingfhpa.go        | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L460-L471                                            | func validateMetricIdentifier                     | N       |
 | validatingmci.go         | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/networking/validation/validation.go#L326-L348                                             | func ValidateIngressSpec                          | N       |
 | validatingmci.go         | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/networking/validation/validation.go#L468C1-L509                                           | func validateIngressBackend                       | N       |
 | validatingmci.go         | https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/networking/validation/validation.go#L547C1-L578                                           | func validateIngressTypedLocalObjectReference     | N       |

pkg/util/lifted/validatingfhpa.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	autoscalingv2 "k8s.io/api/autoscaling/v2"
+	apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
 	apivalidation "k8s.io/apimachinery/pkg/api/validation"
 	pathvalidation "k8s.io/apimachinery/pkg/api/validation/path"
 	"k8s.io/apimachinery/pkg/util/sets"
@@ -12,9 +13,7 @@ import (
 	autoscalingv1alpha1 "github.com/karmada-io/karmada/pkg/apis/autoscaling/v1alpha1"
 )
 
-// This code is directly lifted from the Kubernetes codebase.
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L32-37
-// For reference:
-// https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go
 
 const (
 	// MaxPeriodSeconds is the largest allowed scaling policy period (in seconds)
@@ -23,14 +22,15 @@ const (
 	MaxStabilizationWindowSeconds int32 = 3600
 )
 
-// ValidateFederatedHPAName can be used to check whether the given autoscaler name is valid.
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L103-L119
-// Prefix indicates this name will be used as part of generation, in which case trailing dashes are allowed.
+// +lifted:changed
-var ValidateFederatedHPAName = apivalidation.NameIsDNSSubdomain
 
+// ValidateFederatedHPA validates a FederatedHPA and returns an
+// ErrorList with any errors.
 func ValidateFederatedHPA(fhpa *autoscalingv1alpha1.FederatedHPA) field.ErrorList {
 	errs := field.ErrorList{}
 
-	errs = append(errs, ValidateObjectMeta(&fhpa.ObjectMeta, true, ValidateFederatedHPAName, field.NewPath("metadata"))...)
+	errs = append(errs, apimachineryvalidation.ValidateObjectMeta(&fhpa.ObjectMeta, true, apivalidation.NameIsDNSSubdomain, field.NewPath("metadata"))...)
 
 	// MinReplicasLowerBound represents a minimum value for minReplicas
 	// 0 when HPA scale-to-zero feature is enabled
@@ -42,6 +42,9 @@ func ValidateFederatedHPA(fhpa *autoscalingv1alpha1.FederatedHPA) field.ErrorLis
 	return errs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L55-L78
+// +lifted:changed
+
 func validateFederatedHPASpec(fhpaSpec *autoscalingv1alpha1.FederatedHPASpec, fldPath *field.Path, minReplicasLowerBound int32) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -67,6 +70,8 @@ func validateFederatedHPASpec(fhpaSpec *autoscalingv1alpha1.FederatedHPASpec, fl
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L80-L101
+
 // ValidateCrossVersionObjectReference validates a CrossVersionObjectReference and returns an
 // ErrorList with any errors.
 func ValidateCrossVersionObjectReference(ref autoscalingv2.CrossVersionObjectReference, fldPath *field.Path) field.ErrorList {
@@ -90,6 +95,9 @@ func ValidateCrossVersionObjectReference(ref autoscalingv2.CrossVersionObjectRef
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L140-L148
+// +lifted:changed
+
 // validateFederatedHPAStatus validates an update to status on a FederatedHPA and
 // returns an ErrorList with any errors.
 func validateFederatedHPAStatus(fhpaStatus *autoscalingv2.HorizontalPodAutoscalerStatus) field.ErrorList {
@@ -99,6 +107,9 @@ func validateFederatedHPAStatus(fhpaStatus *autoscalingv2.HorizontalPodAutoscale
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L150-L175
+// +lifted:changed
+
 func validateMetrics(metrics []autoscalingv2.MetricSpec, fldPath *field.Path, minReplicas *int32) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -112,6 +123,8 @@ func validateMetrics(metrics []autoscalingv2.MetricSpec, fldPath *field.Path, mi
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L177-L188
+
 func validateBehavior(behavior *autoscalingv2.HorizontalPodAutoscalerBehavior, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 	if behavior != nil {
@@ -125,9 +138,13 @@ func validateBehavior(behavior *autoscalingv2.HorizontalPodAutoscalerBehavior, f
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L190-L191
+
 var validSelectPolicyTypes = sets.NewString(string(autoscalingv2.MaxChangePolicySelect), string(autoscalingv2.MinChangePolicySelect), string(autoscalingv2.DisabledPolicySelect))
 var validSelectPolicyTypesList = validSelectPolicyTypes.List()
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L193-L218
+
 func validateScalingRules(rules *autoscalingv2.HPAScalingRules, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 	if rules != nil {
@@ -155,9 +172,13 @@ func validateScalingRules(rules *autoscalingv2.HPAScalingRules, fldPath *field.P
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L220-L221
+
 var validPolicyTypes = sets.NewString(string(autoscalingv2.PodsScalingPolicy), string(autoscalingv2.PercentScalingPolicy))
 var validPolicyTypesList = validPolicyTypes.List()
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L223-L239
+
 func validateScalingPolicy(policy autoscalingv2.HPAScalingPolicy, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 	if policy.Type != autoscalingv2.PodsScalingPolicy && policy.Type != autoscalingv2.PercentScalingPolicy {
@@ -176,12 +197,18 @@ func validateScalingPolicy(policy autoscalingv2.HPAScalingPolicy, fldPath *field
 	return allErrs
 }
 
-// TODO: Karmada only supports cpu/memory resource metrics
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L241-L245
-var validMetricSourceTypes = sets.NewString(
+// +lifted:changed
-	string(autoscalingv2.ResourceMetricSourceType))
 
+// TODO: Karmada do not support ExternalMetricSourceType currently
+var validMetricSourceTypes = sets.NewString(
+	string(autoscalingv2.ObjectMetricSourceType), string(autoscalingv2.PodsMetricSourceType),
+	string(autoscalingv2.ResourceMetricSourceType), string(autoscalingv2.ContainerResourceMetricSourceType))
 var validMetricSourceTypesList = validMetricSourceTypes.List()
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L247-L339
+// +lifted:changed
+
 func validateMetricSpec(spec autoscalingv2.MetricSpec, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -194,6 +221,20 @@ func validateMetricSpec(spec autoscalingv2.MetricSpec, fldPath *field.Path) fiel
 	}
 
 	typesPresent := sets.NewString()
+	if spec.Object != nil {
+		typesPresent.Insert("object")
+		if typesPresent.Len() == 1 {
+			allErrs = append(allErrs, validateObjectSource(spec.Object, fldPath.Child("object"))...)
+		}
+	}
+
+	if spec.Pods != nil {
+		typesPresent.Insert("pods")
+		if typesPresent.Len() == 1 {
+			allErrs = append(allErrs, validatePodsSource(spec.Pods, fldPath.Child("pods"))...)
+		}
+	}
+
 	if spec.Resource != nil {
 		typesPresent.Insert("resource")
 		if typesPresent.Len() == 1 {
@@ -201,15 +242,37 @@ func validateMetricSpec(spec autoscalingv2.MetricSpec, fldPath *field.Path) fiel
 		}
 	}
 
+	if spec.ContainerResource != nil {
+		typesPresent.Insert("containerResource")
+		if typesPresent.Len() == 1 {
+			allErrs = append(allErrs, validateContainerResourceSource(spec.ContainerResource, fldPath.Child("containerResource"))...)
+		}
+	}
+
 	var expectedField string
 	switch spec.Type {
 
-	// TODO: Karmada only support resource metrics temporarily
+	case autoscalingv2.ObjectMetricSourceType:
+		if spec.Object == nil {
+			allErrs = append(allErrs, field.Required(fldPath.Child("object"), "must populate information for the given metric source"))
+		}
+		expectedField = "object"
+	case autoscalingv2.PodsMetricSourceType:
+		if spec.Pods == nil {
+			allErrs = append(allErrs, field.Required(fldPath.Child("pods"), "must populate information for the given metric source"))
+		}
+		expectedField = "pods"
 	case autoscalingv2.ResourceMetricSourceType:
 		if spec.Resource == nil {
 			allErrs = append(allErrs, field.Required(fldPath.Child("resource"), "must populate information for the given metric source"))
 		}
 		expectedField = "resource"
+	case autoscalingv2.ContainerResourceMetricSourceType:
+		if spec.ContainerResource == nil {
+			// In K8s, there is a feature gate:HPAContainerMetrics, but we don't know about member clusters, so we enable it by default.
+			allErrs = append(allErrs, field.Required(fldPath.Child("containerResource"), "must populate information for the given metric source"))
+		}
+		expectedField = "containerResource"
 	default:
 		allErrs = append(allErrs, field.NotSupported(fldPath.Child("type"), spec.Type, validMetricSourceTypesList))
 	}
@@ -224,6 +287,69 @@ func validateMetricSpec(spec autoscalingv2.MetricSpec, fldPath *field.Path) fiel
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L340-L352
+
+func validateObjectSource(src *autoscalingv2.ObjectMetricSource, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	allErrs = append(allErrs, ValidateCrossVersionObjectReference(src.DescribedObject, fldPath.Child("describedObject"))...)
+	allErrs = append(allErrs, validateMetricIdentifier(src.Metric, fldPath.Child("metric"))...)
+	allErrs = append(allErrs, validateMetricTarget(src.Target, fldPath.Child("target"))...)
+
+	if src.Target.Value == nil && src.Target.AverageValue == nil {
+		allErrs = append(allErrs, field.Required(fldPath.Child("target").Child("averageValue"), "must set either a target value or averageValue"))
+	}
+
+	return allErrs
+}
+
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L371-L382
+
+func validatePodsSource(src *autoscalingv2.PodsMetricSource, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	allErrs = append(allErrs, validateMetricIdentifier(src.Metric, fldPath.Child("metric"))...)
+	allErrs = append(allErrs, validateMetricTarget(src.Target, fldPath.Child("target"))...)
+
+	if src.Target.AverageValue == nil {
+		allErrs = append(allErrs, field.Required(fldPath.Child("target").Child("averageValue"), "must specify a positive target averageValue"))
+	}
+
+	return allErrs
+}
+
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L383-L410
+
+func validateContainerResourceSource(src *autoscalingv2.ContainerResourceMetricSource, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	if len(src.Name) == 0 {
+		allErrs = append(allErrs, field.Required(fldPath.Child("name"), "must specify a resource name"))
+	} else {
+		allErrs = append(allErrs, ValidateContainerResourceName(string(src.Name), fldPath.Child("name"))...)
+	}
+
+	if len(src.Container) == 0 {
+		allErrs = append(allErrs, field.Required(fldPath.Child("container"), "must specify a container"))
+	} else {
+		allErrs = append(allErrs, ValidateDNS1123Label(src.Container, fldPath.Child("container"))...)
+	}
+
+	allErrs = append(allErrs, validateMetricTarget(src.Target, fldPath.Child("target"))...)
+
+	if src.Target.AverageUtilization == nil && src.Target.AverageValue == nil {
+		allErrs = append(allErrs, field.Required(fldPath.Child("target").Child("averageUtilization"), "must set either a target raw value or a target utilization"))
+	}
+
+	if src.Target.AverageUtilization != nil && src.Target.AverageValue != nil {
+		allErrs = append(allErrs, field.Forbidden(fldPath.Child("target").Child("averageValue"), "may not set both a target raw value and a target utilization"))
+	}
+
+	return allErrs
+}
+
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L412-L430
+
 func validateResourceSource(src *autoscalingv2.ResourceMetricSource, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -244,6 +370,8 @@ func validateResourceSource(src *autoscalingv2.ResourceMetricSource, fldPath *fi
 	return allErrs
 }
 
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L432-L458
+
 func validateMetricTarget(mt autoscalingv2.MetricTarget, fldPath *field.Path) field.ErrorList {
 	allErrs := field.ErrorList{}
 
@@ -271,3 +399,18 @@ func validateMetricTarget(mt autoscalingv2.MetricTarget, fldPath *field.Path) fi
 
 	return allErrs
 }
+
+// +lifted:source=https://github.com/kubernetes/kubernetes/blob/release-1.27/pkg/apis/autoscaling/validation/validation.go#L460-L471
+
+func validateMetricIdentifier(id autoscalingv2.MetricIdentifier, fldPath *field.Path) field.ErrorList {
+	allErrs := field.ErrorList{}
+
+	if len(id.Name) == 0 {
+		allErrs = append(allErrs, field.Required(fldPath.Child("name"), "must specify a metric name"))
+	} else {
+		for _, msg := range pathvalidation.IsValidPathSegmentName(id.Name) {
+			allErrs = append(allErrs, field.Invalid(fldPath.Child("name"), id.Name, msg))
+		}
+	}
+	return allErrs
+}