apiextensions: forbid false x-kubernetes-preserve-unknown-fields

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/deepcopy.go

@@ -258,5 +258,15 @@ func (in *JSONSchemaProps) DeepCopy() *JSONSchemaProps {
 		}
 	}
 
+	if in.XPreserveUnknownFields != nil {
+		in, out := &in.XPreserveUnknownFields, &out.XPreserveUnknownFields
+		if *in == nil {
+			*out = nil
+		} else {
+			*out = new(bool)
+			**out = **in
+		}
+	}
+
 	return out
 }

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/types_jsonschema.go

@@ -61,7 +61,8 @@ type JSONSchemaProps struct {
 	// in the validation schema. This affects fields recursively,
 	// but switches back to normal pruning behaviour if nested
 	// properties or additionalProperties are specified in the schema.
-	XPreserveUnknownFields bool
+	// This can either be true or undefined. False is forbidden.
+	XPreserveUnknownFields *bool
 
 	// x-kubernetes-embedded-resource defines that the value is an
 	// embedded Kubernetes runtime.Object, with TypeMeta and

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/deepcopy.go

@@ -234,5 +234,15 @@ func (in *JSONSchemaProps) DeepCopy() *JSONSchemaProps {
 		}
 	}
 
+	if in.XPreserveUnknownFields != nil {
+		in, out := &in.XPreserveUnknownFields, &out.XPreserveUnknownFields
+		if *in == nil {
+			*out = nil
+		} else {
+			*out = new(bool)
+			**out = **in
+		}
+	}
+
 	return out
 }

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/generated.proto

@@ -449,6 +449,7 @@ message JSONSchemaProps {
   // in the validation schema. This affects fields recursively,
   // but switches back to normal pruning behaviour if nested
   // properties or additionalProperties are specified in the schema.
+  // This can either be true or undefined. False is forbidden.
   optional bool xKubernetesPreserveUnknownFields = 38;
 
   // x-kubernetes-embedded-resource defines that the value is an

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1/types_jsonschema.go

@@ -61,7 +61,8 @@ type JSONSchemaProps struct {
 	// in the validation schema. This affects fields recursively,
 	// but switches back to normal pruning behaviour if nested
 	// properties or additionalProperties are specified in the schema.
-	XPreserveUnknownFields bool `json:"x-kubernetes-preserve-unknown-fields,omitempty" protobuf:"bytes,38,opt,name=xKubernetesPreserveUnknownFields"`
+	// This can either be true or undefined. False is forbidden.
+	XPreserveUnknownFields *bool `json:"x-kubernetes-preserve-unknown-fields,omitempty" protobuf:"bytes,38,opt,name=xKubernetesPreserveUnknownFields"`
 
 	// x-kubernetes-embedded-resource defines that the value is an
 	// embedded Kubernetes runtime.Object, with TypeMeta and

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/BUILD

@@ -34,6 +34,7 @@ go_test(
         "//staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/validation/field:go_default_library",
+        "//vendor/k8s.io/utils/pointer:go_default_library",
     ],
 )
 

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation.go

@@ -673,6 +673,10 @@ func ValidateCustomResourceDefinitionOpenAPISchema(schema *apiextensions.JSONSch
 		}
 	}
 
+	if schema.XPreserveUnknownFields != nil && *schema.XPreserveUnknownFields == false {
+		allErrs = append(allErrs, field.Invalid(fldPath.Child("x-kubernetes-preserve-unknown-fields"), *schema.XPreserveUnknownFields, "must be true or undefined"))
+	}
+
 	return allErrs
 }
 

staging/src/k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/validation/validation_test.go

@@ -22,6 +22,7 @@ import (
 	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/validation/field"
+	"k8s.io/utils/pointer"
 )
 
 type validationMatch struct {
@@ -935,6 +936,41 @@ func TestValidateCustomResourceDefinition(t *testing.T) {
 				invalid("spec", "versions"),
 			},
 		},
+		{
+			name: "x-kubernetes-preserve-unknown-field: false",
+			resource: &apiextensions.CustomResourceDefinition{
+				ObjectMeta: metav1.ObjectMeta{Name: "plural.group.com"},
+				Spec: apiextensions.CustomResourceDefinitionSpec{
+					Group:   "group.com",
+					Version: "version",
+					Validation: &apiextensions.CustomResourceValidation{
+						OpenAPIV3Schema: &apiextensions.JSONSchemaProps{
+							XPreserveUnknownFields: pointer.BoolPtr(false),
+						},
+					},
+					Versions: []apiextensions.CustomResourceDefinitionVersion{
+						{
+							Name:    "version",
+							Served:  true,
+							Storage: true,
+						},
+					},
+					Scope: apiextensions.NamespaceScoped,
+					Names: apiextensions.CustomResourceDefinitionNames{
+						Plural:   "plural",
+						Singular: "singular",
+						Kind:     "Plural",
+						ListKind: "PluralList",
+					},
+				},
+				Status: apiextensions.CustomResourceDefinitionStatus{
+					StoredVersions: []string{"version"},
+				},
+			},
+			errors: []validationMatch{
+				invalid("spec", "validation", "openAPIV3Schema", "x-kubernetes-preserve-unknown-fields"),
+			},
+		},
 	}
 
 	for _, tc := range tests {

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/convert.go

@@ -241,11 +241,19 @@ func newExtensions(s *apiextensions.JSONSchemaProps) (*Extensions, error) {
 		return nil, nil
 	}
 
-	return &Extensions{
-		XPreserveUnknownFields: s.XPreserveUnknownFields,
-		XEmbeddedResource:      s.XEmbeddedResource,
-		XIntOrString:           s.XIntOrString,
-	}, nil
+	ret := &Extensions{
+		XEmbeddedResource: s.XEmbeddedResource,
+		XIntOrString:      s.XIntOrString,
+	}
+
+	if s.XPreserveUnknownFields != nil {
+		if !*s.XPreserveUnknownFields {
+			return nil, fmt.Errorf("'x-kubernetes-preserve-unknown-fields' must be true or undefined")
+		}
+		ret.XPreserveUnknownFields = true
+	}
+
+	return ret, nil
 }
 
 // validateUnsupportedFields checks that those fields rejected by validation are actually unset.

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/structural.go

@@ -66,6 +66,8 @@ type Extensions struct {
 	// in the validation schema. This affects fields recursively,
 	// but switches back to normal pruning behaviour if nested
 	// properties or additionalProperties are specified in the schema.
+	// False means that the pruning behaviour is inherited from the parent.
+	// False does not mean to activate pruning.
 	XPreserveUnknownFields bool
 
 	// x-kubernetes-embedded-resource defines that the value is an

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/validation/validation.go

@@ -195,8 +195,8 @@ func ConvertJSONSchemaPropsWithPostProcess(in *apiextensions.JSONSchemaProps, ou
 		}
 	}
 
-	if in.XPreserveUnknownFields {
-		out.VendorExtensible.AddExtension("x-kubernetes-preserve-unknown-fields", true)
+	if in.XPreserveUnknownFields != nil {
+		out.VendorExtensible.AddExtension("x-kubernetes-preserve-unknown-fields", *in.XPreserveUnknownFields)
 	}
 	if in.XEmbeddedResource {
 		out.VendorExtensible.AddExtension("x-kubernetes-embedded-resource", true)