Add AdmissionReviewVersions to admissionregistration and default it

pkg/apis/admissionregistration/fuzzer/fuzzer.go

@@ -43,6 +43,7 @@ var Funcs = func(codecs runtimeserializer.CodecFactory) []interface{} {
 				i := int32(30)
 				obj.TimeoutSeconds = &i
 			}
+			obj.AdmissionReviewVersions = []string{"v1beta1"}
 		},
 	}
 }

pkg/apis/admissionregistration/types.go

@@ -239,6 +239,15 @@ type Webhook struct {
 	// The timeout value must be between 1 and 30 seconds.
 	// +optional
 	TimeoutSeconds *int32
+
+	// AdmissionReviewVersions is an ordered list of preferred `AdmissionReview`
+	// versions the Webhook expects. API server will try to use first version in
+	// the list which it supports. If none of the versions specified in this list
+	// supported by API server, validation will fail for this object.
+	// If the webhook configuration has already been persisted with a version apiserver
+	// does not understand, calls to the webhook will fail and be subject to the failure policy.
+	// +optional
+	AdmissionReviewVersions []string
 }
 
 // RuleWithOperations is a tuple of Operations and Resources. It is recommended to make

pkg/apis/admissionregistration/v1beta1/defaults.go

@@ -44,6 +44,10 @@ func SetDefaults_Webhook(obj *admissionregistrationv1beta1.Webhook) {
 		obj.TimeoutSeconds = new(int32)
 		*obj.TimeoutSeconds = 30
 	}
+
+	if len(obj.AdmissionReviewVersions) == 0 {
+		obj.AdmissionReviewVersions = []string{admissionregistrationv1beta1.SchemeGroupVersion.Version}
+	}
 }
 
 func SetDefaults_Rule(obj *admissionregistrationv1beta1.Rule) {

pkg/apis/admissionregistration/validation/validation.go

@@ -24,9 +24,11 @@ import (
 	metav1validation "k8s.io/apimachinery/pkg/apis/meta/v1/validation"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/validation"
+	utilvalidation "k8s.io/apimachinery/pkg/util/validation"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apiserver/pkg/util/webhook"
 	"k8s.io/kubernetes/pkg/apis/admissionregistration"
+	"k8s.io/kubernetes/pkg/apis/admissionregistration/v1beta1"
 )
 
 func hasWildcard(slice []string) bool {
@@ -150,18 +152,71 @@ func validateRule(rule *admissionregistration.Rule, fldPath *field.Path, allowSu
 	return allErrors
 }
 
+var AcceptedAdmissionReviewVersions = []string{v1beta1.SchemeGroupVersion.Version}
+
+func isAcceptedAdmissionReviewVersion(v string) bool {
+	for _, version := range AcceptedAdmissionReviewVersions {
+		if v == version {
+			return true
+		}
+	}
+	return false
+}
+
+func validateAdmissionReviewVersions(versions []string, requireRecognizedVersion bool, fldPath *field.Path) field.ErrorList {
+	allErrors := field.ErrorList{}
+
+	// Currently only v1beta1 accepted in AdmissionReviewVersions
+	if len(versions) < 1 {
+		allErrors = append(allErrors, field.Required(fldPath, ""))
+	} else {
+		seen := map[string]bool{}
+		hasAcceptedVersion := false
+		for i, v := range versions {
+			if seen[v] {
+				allErrors = append(allErrors, field.Invalid(fldPath.Index(i), v, "duplicate version"))
+				continue
+			}
+			seen[v] = true
+			for _, errString := range utilvalidation.IsDNS1035Label(v) {
+				allErrors = append(allErrors, field.Invalid(fldPath.Index(i), v, errString))
+			}
+			if isAcceptedAdmissionReviewVersion(v) {
+				hasAcceptedVersion = true
+			}
+		}
+		if requireRecognizedVersion && !hasAcceptedVersion {
+			allErrors = append(allErrors, field.Invalid(
+				fldPath, versions,
+				fmt.Sprintf("none of the versions accepted by this server. accepted version(s) are %v",
+					strings.Join(AcceptedAdmissionReviewVersions, ", "))))
+		}
+	}
+	return allErrors
+}
+
 func ValidateValidatingWebhookConfiguration(e *admissionregistration.ValidatingWebhookConfiguration) field.ErrorList {
+	return validateValidatingWebhookConfiguration(e, true)
+}
+
+func validateValidatingWebhookConfiguration(e *admissionregistration.ValidatingWebhookConfiguration, requireRecognizedVersion bool) field.ErrorList {
 	allErrors := genericvalidation.ValidateObjectMeta(&e.ObjectMeta, false, genericvalidation.NameIsDNSSubdomain, field.NewPath("metadata"))
 	for i, hook := range e.Webhooks {
 		allErrors = append(allErrors, validateWebhook(&hook, field.NewPath("webhooks").Index(i))...)
+		allErrors = append(allErrors, validateAdmissionReviewVersions(hook.AdmissionReviewVersions, requireRecognizedVersion, field.NewPath("webhooks").Index(i).Child("admissionReviewVersions"))...)
 	}
 	return allErrors
 }
 
 func ValidateMutatingWebhookConfiguration(e *admissionregistration.MutatingWebhookConfiguration) field.ErrorList {
+	return validateMutatingWebhookConfiguration(e, true)
+}
+
+func validateMutatingWebhookConfiguration(e *admissionregistration.MutatingWebhookConfiguration, requireRecognizedVersion bool) field.ErrorList {
 	allErrors := genericvalidation.ValidateObjectMeta(&e.ObjectMeta, false, genericvalidation.NameIsDNSSubdomain, field.NewPath("metadata"))
 	for i, hook := range e.Webhooks {
 		allErrors = append(allErrors, validateWebhook(&hook, field.NewPath("webhooks").Index(i))...)
+		allErrors = append(allErrors, validateAdmissionReviewVersions(hook.AdmissionReviewVersions, requireRecognizedVersion, field.NewPath("webhooks").Index(i).Child("admissionReviewVersions"))...)
 	}
 	return allErrors
 }
@@ -247,10 +302,28 @@ func validateRuleWithOperations(ruleWithOperations *admissionregistration.RuleWi
 	return allErrors
 }
 
+// hasAcceptedAdmissionReviewVersions returns true if all webhooks have at least one
+// admission review version this apiserver accepts.
+func hasAcceptedAdmissionReviewVersions(webhooks []admissionregistration.Webhook) bool {
+	for _, hook := range webhooks {
+		hasRecognizedVersion := false
+		for _, version := range hook.AdmissionReviewVersions {
+			if isAcceptedAdmissionReviewVersion(version) {
+				hasRecognizedVersion = true
+				break
+			}
+		}
+		if !hasRecognizedVersion && len(hook.AdmissionReviewVersions) > 0 {
+			return false
+		}
+	}
+	return true
+}
+
 func ValidateValidatingWebhookConfigurationUpdate(newC, oldC *admissionregistration.ValidatingWebhookConfiguration) field.ErrorList {
-	return ValidateValidatingWebhookConfiguration(newC)
+	return validateValidatingWebhookConfiguration(newC, hasAcceptedAdmissionReviewVersions(oldC.Webhooks))
 }
 
 func ValidateMutatingWebhookConfigurationUpdate(newC, oldC *admissionregistration.MutatingWebhookConfiguration) field.ErrorList {
-	return ValidateMutatingWebhookConfiguration(newC)
+	return validateMutatingWebhookConfiguration(newC, hasAcceptedAdmissionReviewVersions(oldC.Webhooks))
 }