Add OpenAPI extensions to openapi_gen (Definition Generator)

cmd/libs/go2idl/openapi-gen/README

@@ -2,3 +2,12 @@
 
 - To generate definition for a specific type or package add "+k8s:openapi-gen=true" tag to the type/package comment lines.
 - To exclude a type or a member from a tagged package/type, add "+k8s:openapi-gen=false" tag to the comment lines.
+
+# OpenAPI Extensions
+OpenAPI spec can have extensions on types. To define one or more extensions on a type or its member
+add "+k8s:openapi-gen=x-kubernetes-$NAME:$VALUE" to the comment lines before type/member. A type/member can
+have multiple extensions. The rest of the line in the comment will be used as $VALUE so there is no need to
+escape or quote the value string. Extensions can be use to pass more information to client generators or
+documentation generators. For example a type my have a friendly name to be displayed in documentation or
+being used in a client's fluent interface.
+

cmd/libs/go2idl/openapi-gen/generators/openapi.go

@@ -40,15 +40,17 @@ const tagOptional = "optional"
 
 // Known values for the tag.
 const (
-	tagValueTrue  = "true"
-	tagValueFalse = "false"
+	tagValueTrue       = "true"
+	tagValueFalse      = "false"
+	tagExtensionPrefix = "x-kubernetes-"
 )
 
+func getOpenAPITagValue(comments []string) []string {
+	return types.ExtractCommentTags("+", comments)[tagName]
+}
+
 func hasOpenAPITagValue(comments []string, value string) bool {
-	tagValues := types.ExtractCommentTags("+", comments)[tagName]
-	if tagValues == nil {
-		return false
-	}
+	tagValues := getOpenAPITagValue(comments)
 	for _, val := range tagValues {
 		if val == value {
 			return true
@@ -342,6 +344,33 @@ func (g openAPITypeWriter) generate(t *types.Type) error {
 			}
 			g.Do("\"$.$\",", k)
 		}
+		g.Do("},\n", nil)
+		if err := g.generateExtensions(t.CommentLines); err != nil {
+			return err
+		}
+		g.Do("},\n", nil)
+	}
+	return nil
+}
+
+func (g openAPITypeWriter) generateExtensions(CommentLines []string) error {
+	tagValues := getOpenAPITagValue(CommentLines)
+	anyExtension := false
+	for _, val := range tagValues {
+		if strings.HasPrefix(val, tagExtensionPrefix) {
+			if !anyExtension {
+				g.Do("spec.VendorExtensible: {\nExtensions: spec.Extensions{\n", nil)
+				anyExtension = true
+			}
+			parts := strings.SplitN(val, ":", 2)
+			if len(parts) != 2 {
+				return fmt.Errorf("Invalid extension value: %v", val)
+			}
+			g.Do("\"$.$\": ", parts[0])
+			g.Do("\"$.$\",\n", parts[1])
+		}
+	}
+	if anyExtension {
 		g.Do("},\n},\n", nil)
 	}
 	return nil
@@ -396,6 +425,9 @@ func (g openAPITypeWriter) generateProperty(m *types.Member) error {
 		return nil
 	}
 	g.Do("\"$.$\": {\n", name)
+	if err := g.generateExtensions(m.CommentLines); err != nil {
+		return err
+	}
 	g.Do("SchemaProps: spec.SchemaProps{\n", nil)
 	g.generateDescription(m.CommentLines)
 	jsonTags := getJsonTags(m)

cmd/libs/go2idl/openapi-gen/generators/openapi_test.go

@@ -71,7 +71,8 @@ func TestSimple(t *testing.T) {
 package foo
 
 // Blah is a test.
-// +k8s:openapi=true
+// +k8s:openapi-gen=true
+// +k8s:openapi-gen=x-kubernetes-type-tag:type_test
 type Blah struct {
 	// A simple string
 	String string
@@ -107,6 +108,9 @@ type Blah struct {
 	Float32 float32
 	// a base64 encoded characters
 	ByteArray []byte
+	// a member with an extension
+	// +k8s:openapi-gen=x-kubernetes-member-tag:member_test
+	WithExtension string
 }
 		`)
 	if err != nil {
@@ -222,12 +226,29 @@ Type: []string{"string"},
 Format: "byte",
 },
 },
+"WithExtension": {
+spec.VendorExtensible: {
+Extensions: spec.Extensions{
+"x-kubernetes-member-tag": "member_test",
 },
-Required: []string{"String","Int64","Int32","Int16","Int8","Uint","Uint64","Uint32","Uint16","Uint8","Byte","Bool","Float64","Float32","ByteArray"},
+},
+SchemaProps: spec.SchemaProps{
+Description: "a member with an extension",
+Type: []string{"string"},
+Format: "",
+},
+},
+},
+Required: []string{"String","Int64","Int32","Int16","Int8","Uint","Uint64","Uint32","Uint16","Uint8","Byte","Bool","Float64","Float32","ByteArray","WithExtension"},
 },
 },
 Dependencies: []string{
 },
+spec.VendorExtensible: {
+Extensions: spec.Extensions{
+"x-kubernetes-type-tag": "type_test",
+},
+},
 },
 `, buffer.String())
 }