apiextensions: switch OpenAPI pubilshing to structural schema

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/builder.go

@@ -26,6 +26,7 @@ import (
 	"github.com/go-openapi/spec"
 
 	v1 "k8s.io/api/autoscaling/v1"
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	metav1beta1 "k8s.io/apimachinery/pkg/apis/meta/v1beta1"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -58,22 +59,24 @@ var namer *openapi.DefinitionNamer
 
 // BuildSwagger builds swagger for the given crd in the given version
 func BuildSwagger(crd *apiextensions.CustomResourceDefinition, version string) (*spec.Swagger, error) {
-	var schema *spec.Schema
+	var schema *structuralschema.Structural
 	s, err := apiextensions.GetSchemaForVersion(crd, version)
 	if err != nil {
 		return nil, err
 	}
 	if s != nil && s.OpenAPIV3Schema != nil {
-		schema, err = ConvertJSONSchemaPropsToOpenAPIv2Schema(s.OpenAPIV3Schema)
-		if err != nil {
-			return nil, err
+		ss, err := structuralschema.NewStructural(s.OpenAPIV3Schema)
+		if err == nil && len(structuralschema.ValidateStructural(ss, nil)) == 0 {
+			// skip non-structural schemas
+			schema = ss.Unfold()
 		}
 	}
+
 	// TODO(roycaihw): remove the WebService templating below. The following logic
 	// comes from function registerResourceHandlers() in k8s.io/apiserver.
 	// Alternatives are either (ideally) refactoring registerResourceHandlers() to
 	// reuse the code, or faking an APIInstaller for CR to feed to registerResourceHandlers().
-	b := newBuilder(crd, version, schema)
+	b := newBuilder(crd, version, schema, true)
 
 	// Sample response types for building web service
 	sample := &CRDCanonicalTypeNamer{
@@ -288,23 +291,27 @@ func (b *builder) buildRoute(root, path, action, verb string, sample interface{}
 
 // buildKubeNative builds input schema with Kubernetes' native object meta, type meta and
 // extensions
-func (b *builder) buildKubeNative(schema *spec.Schema) *spec.Schema {
+func (b *builder) buildKubeNative(schema *structuralschema.Structural, v2 bool) (ret *spec.Schema) {
 	// only add properties if we have a schema. Otherwise, kubectl would (wrongly) assume additionalProperties=false
 	// and forbid anything outside of apiVersion, kind and metadata. We have to fix kubectl to stop doing this, e.g. by
 	// adding additionalProperties=true support to explicitly allow additional fields.
 	// TODO: fix kubectl to understand additionalProperties=true
 	if schema == nil {
-		schema = &spec.Schema{
+		ret = &spec.Schema{
 			SchemaProps: spec.SchemaProps{Type: []string{"object"}},
 		}
 		// no, we cannot add more properties here, not even TypeMeta/ObjectMeta because kubectl will complain about
 		// unknown fields for anything else.
 	} else {
-		schema.SetProperty("metadata", *spec.RefSchema(objectMetaSchemaRef).
+		if v2 {
+			schema = ToStructuralOpenAPIV2(schema)
+		}
+		ret = schema.ToGoOpenAPI()
+		ret.SetProperty("metadata", *spec.RefSchema(objectMetaSchemaRef).
 			WithDescription(swaggerPartialObjectMetadataDescriptions["metadata"]))
-		addTypeMetaProperties(schema)
+		addTypeMetaProperties(ret)
 	}
-	schema.AddExtension(endpoints.ROUTE_META_GVK, []interface{}{
+	ret.AddExtension(endpoints.ROUTE_META_GVK, []interface{}{
 		map[string]interface{}{
 			"group":   b.group,
 			"version": b.version,
@@ -312,7 +319,7 @@ func (b *builder) buildKubeNative(schema *spec.Schema) *spec.Schema {
 		},
 	})
 
-	return schema
+	return ret
 }
 
 // getDefinition gets definition for given Kubernetes type. This function is extracted from
@@ -391,7 +398,7 @@ func (b *builder) getOpenAPIConfig() *common.Config {
 	}
 }
 
-func newBuilder(crd *apiextensions.CustomResourceDefinition, version string, schema *spec.Schema) *builder {
+func newBuilder(crd *apiextensions.CustomResourceDefinition, version string, schema *structuralschema.Structural, v2 bool) *builder {
 	b := &builder{
 		schema: &spec.Schema{
 			SchemaProps: spec.SchemaProps{Type: []string{"object"}},
@@ -410,7 +417,7 @@ func newBuilder(crd *apiextensions.CustomResourceDefinition, version string, sch
 	}
 
 	// Pre-build schema with Kubernetes native properties
-	b.schema = b.buildKubeNative(schema)
+	b.schema = b.buildKubeNative(schema, v2)
 	b.listSchema = b.buildListSchema()
 
 	return b

staging/src/k8s.io/apiextensions-apiserver/pkg/controller/openapi/conversion.go

@@ -17,106 +17,60 @@ limitations under the License.
 package openapi
 
 import (
-	"strings"
-
-	"github.com/go-openapi/spec"
-
-	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
-	"k8s.io/apiextensions-apiserver/pkg/apiserver/validation"
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
 )
 
-// ConvertJSONSchemaPropsToOpenAPIv2Schema converts our internal OpenAPI v3 schema
-// (*apiextensions.JSONSchemaProps) to an OpenAPI v2 schema (*spec.Schema).
-func ConvertJSONSchemaPropsToOpenAPIv2Schema(in *apiextensions.JSONSchemaProps) (*spec.Schema, error) {
+// ToStructuralOpenAPIV2 converts our internal OpenAPI v3 structural schema to
+// to a v2 compatible schema.
+func ToStructuralOpenAPIV2(in *structuralschema.Structural) *structuralschema.Structural {
 	if in == nil {
-		return nil, nil
+		return nil
 	}
 
-	// dirty hack to temporarily set the type at the root. See continuation at the func bottom.
-	// TODO: remove for Kubernetes 1.15
-	oldRootType := in.Type
-	if len(in.Type) == 0 {
-		in.Type = "object"
-	}
+	out := in.DeepCopy()
 
 	// Remove unsupported fields in OpenAPI v2 recursively
-	out := new(spec.Schema)
-	validation.ConvertJSONSchemaPropsWithPostProcess(in, out, func(p *spec.Schema) error {
-		p.OneOf = nil
-		// TODO(roycaihw): preserve cases where we only have one subtree in AnyOf, same for OneOf
-		p.AnyOf = nil
-		p.Not = nil
-
-		// TODO: drop everything below in 1.15 when we have passed one version skew towards kube-openapi in <1.14, which rejects valid openapi schemata
-
-		if p.Ref.String() != "" {
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R95
-			p.Properties = nil
-
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R99
-			p.Type = nil
-
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R104
-			if !strings.HasPrefix(p.Ref.String(), "#/definitions/") {
-				p.Ref = spec.Ref{}
-			}
-		}
-
-		switch {
-		case len(p.Type) == 2 && (p.Type[0] == "null" || p.Type[1] == "null"):
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-ce77fea74b9dd098045004410023e0c3R219
-			p.Type = nil
-		case len(p.Type) == 1:
-			switch p.Type[0] {
-			case "null":
-				// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-ce77fea74b9dd098045004410023e0c3R219
-				p.Type = nil
-			case "array":
-				// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R183
-				// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R184
-				if p.Items == nil || (p.Items.Schema == nil && len(p.Items.Schemas) != 1) {
-					p.Type = nil
-					p.Items = nil
+	mapper := structuralschema.Visitor{
+		Structural: func(s *structuralschema.Structural) bool {
+			changed := false
+			if s.ValueValidation != nil {
+				if s.ValueValidation.AllOf != nil {
+					s.ValueValidation.AllOf = nil
+					changed = true
+				}
+				if s.ValueValidation.OneOf != nil {
+					s.ValueValidation.OneOf = nil
+					changed = true
+				}
+				if s.ValueValidation.AnyOf != nil {
+					s.ValueValidation.AnyOf = nil
+					changed = true
+				}
+				if s.ValueValidation.Not != nil {
+					s.ValueValidation.Not = nil
+					changed = true
 				}
 			}
-		case len(p.Type) > 1:
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R272
-			// We also set Properties to null to enforce parseArbitrary at https://github.com/kubernetes/kube-openapi/blob/814a8073653e40e0e324205d093770d4e7bb811f/pkg/util/proto/document.go#L247
-			p.Type = nil
-			p.Properties = nil
-		default:
-			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R248
-			p.Properties = nil
-		}
 
-		// normalize items
-		if p.Items != nil && len(p.Items.Schemas) == 1 {
-			p.Items = &spec.SchemaOrArray{Schema: &p.Items.Schemas[0]}
-		}
+			// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-ce77fea74b9dd098045004410023e0c3R219
+			if s.Nullable {
+				s.Type = ""
+				s.Nullable = false
 
-		// general fixups not supported by gnostic
-		p.ID = ""
-		p.Schema = ""
-		p.Definitions = nil
-		p.AdditionalItems = nil
-		p.Dependencies = nil
-		p.PatternProperties = nil
-		if p.ExternalDocs != nil && len(p.ExternalDocs.URL) == 0 {
-			p.ExternalDocs = nil
-		}
-		if p.Items != nil && p.Items.Schemas != nil {
-			p.Items = nil
-		}
+				// untyped values break if items or properties are set in kubectl
+				// https://github.com/kubernetes/kube-openapi/pull/143/files#diff-62afddb578e9db18fb32ffb6b7802d92R183
+				s.Items = nil
+				s.Properties = nil
 
-		return nil
-	})
+				changed = true
+			}
 
-	// restore root level type in input, and remove it in output if we had added it
-	// TODO: remove with Kubernetes 1.15
-	in.Type = oldRootType
-	if len(oldRootType) == 0 {
-		out.Type = nil
+			return changed
+		},
+		// we drop all junctors above, and hence, never reach nested value validations
+		NestedValueValidation: nil,
 	}
+	mapper.Visit(out)
 
-	return out, nil
+	return out
 }

test/integration/master/crd_test.go

@@ -160,6 +160,7 @@ func TestCRDOpenAPI(t *testing.T) {
 			},
 			Validation: &apiextensionsv1beta1.CustomResourceValidation{
 				OpenAPIV3Schema: &apiextensionsv1beta1.JSONSchemaProps{
+					Type: "object",
 					Properties: map[string]apiextensionsv1beta1.JSONSchemaProps{
 						"foo": {Type: "string"},
 					},