Separate Build and Serving parts of OpenAPI spec handler

staging/src/k8s.io/apiserver/pkg/server/openapi/openapi.go

@@ -17,26 +17,17 @@ limitations under the License.
 package openapi
 
 import (
-	"bytes"
-	"compress/gzip"
 	"crypto/sha512"
 	"encoding/json"
 	"fmt"
-	"gopkg.in/yaml.v2"
-	"mime"
 	"net/http"
 	"reflect"
 	"strings"
-	"time"
 
 	"github.com/emicklei/go-restful"
 	"github.com/go-openapi/spec"
-	"github.com/golang/protobuf/proto"
-	"github.com/googleapis/gnostic/OpenAPIv2"
-	"github.com/googleapis/gnostic/compiler"
 
 	"k8s.io/apimachinery/pkg/openapi"
-	genericmux "k8s.io/apiserver/pkg/server/mux"
 	"k8s.io/apiserver/pkg/util/trie"
 )
 
@@ -55,10 +46,6 @@ const (
 type openAPI struct {
 	config       *openapi.Config
 	swagger      *spec.Swagger
-	swaggerBytes []byte
-	swaggerPb    []byte
-	swaggerPbGz  []byte
-	lastModified time.Time
 	protocolList []string
 	definitions  map[string]openapi.OpenAPIDefinition
 }
@@ -67,17 +54,9 @@ func computeEtag(data []byte) string {
 	return fmt.Sprintf("\"%X\"", sha512.Sum512(data))
 }
 
-// RegisterOpenAPIService registers a handler to provides standard OpenAPI specification.
-func RegisterOpenAPIService(servePath string, webServices []*restful.WebService, config *openapi.Config, mux *genericmux.PathRecorderMux) (err error) {
-
-	if !strings.HasSuffix(servePath, JSON_EXT) {
-		return fmt.Errorf("Serving path must ends with \"%s\".", JSON_EXT)
-	}
-
-	servePathBase := servePath[:len(servePath)-len(JSON_EXT)]
-
+func BuildSwaggerSpec(webServices []*restful.WebService, config *openapi.Config) (*spec.Swagger, error) {
 	o := openAPI{
-		config:    config,
+		config: config,
 		swagger: &spec.Swagger{
 			SwaggerProps: spec.SwaggerProps{
 				Swagger:     OpenAPIVersion,
@@ -88,44 +67,12 @@ func RegisterOpenAPIService(servePath string, webServices []*restful.WebService,
 		},
 	}
 
-	err = o.init(webServices)
+	err := o.init(webServices)
 	if err != nil {
-		return err
-	}
-
-	mime.AddExtensionType(".json", MIME_JSON)
-	mime.AddExtensionType(".pb-v1", MIME_PB)
-	mime.AddExtensionType(".gz", MIME_PB_GZ)
-
-	type fileInfo struct {
-		ext  string
-		data []byte
-	}
-
-	files := []fileInfo{
-		{".json", o.swaggerBytes},
-		{"-2.0.0.json", o.swaggerBytes},
-		{"-2.0.0.pb-v1", o.swaggerPb},
-		{"-2.0.0.pb-v1.gz", o.swaggerPbGz},
-	}
-
-	for _, file := range files {
-		path := servePathBase + file.ext
-		data := file.data
-		etag := computeEtag(file.data)
-		mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
-			if r.URL.Path != path {
-				w.WriteHeader(http.StatusNotFound)
-				w.Write([]byte("Path not found!"))
-				return
-			}
-			w.Header().Set("Etag", etag)
-			// ServeContent will take care of caching using eTag.
-			http.ServeContent(w, r, path, o.lastModified, bytes.NewReader(data))
-		})
+		return nil, err
 	}
 
-	return nil
+	return o.swagger, nil
 }
 
 func (o *openAPI) init(webServices []*restful.WebService) error {
@@ -141,7 +88,7 @@ func (o *openAPI) init(webServices []*restful.WebService) error {
 	}
 	o.definitions = o.config.GetDefinitions(func(name string) spec.Ref {
 		defName, _ := o.config.GetDefinitionName(name)
-		return spec.MustCreateRef("#/definitions/" + openapi.EscapeJsonPointer(defName))
+		return spec.MustCreateRef(DEFINITION_PREFIX + openapi.EscapeJsonPointer(defName))
 	})
 	if o.config.CommonResponses == nil {
 		o.config.CommonResponses = map[int]spec.Response{}
@@ -161,41 +108,9 @@ func (o *openAPI) init(webServices []*restful.WebService) error {
 		}
 	}
 
-	o.swaggerBytes, err = json.MarshalIndent(o.swagger, " ", " ")
-	if err != nil {
-		return err
-	}
-	o.swaggerPb, err = toProtoBinary(o.swaggerBytes)
-	if err != nil {
-		return err
-	}
-	o.swaggerPbGz = toGzip(o.swaggerPb)
-	o.lastModified = time.Now()
-
 	return nil
 }
 
-func toProtoBinary(spec []byte) ([]byte, error) {
-	var info yaml.MapSlice
-	err := yaml.Unmarshal(spec, &info)
-	if err != nil {
-		return nil, err
-	}
-	document, err := openapi_v2.NewDocument(info, compiler.NewContext("$root", nil))
-	if err != nil {
-		return nil, err
-	}
-	return proto.Marshal(document)
-}
-
-func toGzip(data []byte) []byte {
-	var buf bytes.Buffer
-	zw := gzip.NewWriter(&buf)
-	zw.Write(data)
-	zw.Close()
-	return buf.Bytes()
-}
-
 func getCanonicalizeTypeName(t reflect.Type) string {
 	if t.PkgPath() == "" {
 		return t.Name()
@@ -251,7 +166,7 @@ func (o *openAPI) buildDefinitionForType(sample interface{}) (string, error) {
 		return "", err
 	}
 	defName, _ := o.config.GetDefinitionName(name)
-	return "#/definitions/" + openapi.EscapeJsonPointer(defName), nil
+	return DEFINITION_PREFIX + openapi.EscapeJsonPointer(defName), nil
 }
 
 // buildPaths builds OpenAPI paths using go-restful's web services.

staging/src/k8s.io/apiserver/pkg/server/openapi/openapi_handler.go

+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package openapi
+
+import (
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"fmt"
+	"mime"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/go-openapi/spec"
+	"github.com/golang/protobuf/proto"
+	"github.com/googleapis/gnostic/OpenAPIv2"
+	"github.com/googleapis/gnostic/compiler"
+	"gopkg.in/yaml.v2"
+	genericmux "k8s.io/apiserver/pkg/server/mux"
+)
+
+type OpenAPIService struct {
+	orgSpec      *spec.Swagger
+	specBytes    []byte
+	specPb       []byte
+	specPbGz     []byte
+	lastModified time.Time
+	updateHooks  []func(*http.Request)
+}
+
+// RegisterOpenAPIService registers a handler to provides standard OpenAPI specification.
+func RegisterOpenAPIService(openapiSpec *spec.Swagger, servePath string, mux *genericmux.PathRecorderMux) (*OpenAPIService, error) {
+	if !strings.HasSuffix(servePath, JSON_EXT) {
+		return nil, fmt.Errorf("Serving path must ends with \"%s\".", JSON_EXT)
+	}
+
+	servePathBase := servePath[:len(servePath)-len(JSON_EXT)]
+
+	o := OpenAPIService{}
+	if err := o.UpdateSpec(openapiSpec); err != nil {
+		return nil, err
+	}
+
+	mime.AddExtensionType(".json", MIME_JSON)
+	mime.AddExtensionType(".pb-v1", MIME_PB)
+	mime.AddExtensionType(".gz", MIME_PB_GZ)
+
+	type fileInfo struct {
+		ext     string
+		getData func() []byte
+	}
+
+	files := []fileInfo{
+		{".json", o.getSwaggerBytes},
+		{"-2.0.0.json", o.getSwaggerBytes},
+		{"-2.0.0.pb-v1", o.getSwaggerPbBytes},
+		{"-2.0.0.pb-v1.gz", o.getSwaggerPbGzBytes},
+	}
+
+	for _, file := range files {
+		path := servePathBase + file.ext
+		getData := file.getData
+		mux.HandleFunc(path, func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path != path {
+				w.WriteHeader(http.StatusNotFound)
+				w.Write([]byte("Path not found!"))
+				return
+			}
+			o.update(r)
+			data := getData()
+			etag := computeEtag(data)
+			w.Header().Set("Etag", etag)
+			// ServeContent will take care of caching using eTag.
+			http.ServeContent(w, r, path, o.lastModified, bytes.NewReader(data))
+		})
+	}
+
+	return &o, nil
+}
+
+func (o *OpenAPIService) getSwaggerBytes() []byte {
+	return o.specBytes
+}
+
+func (o *OpenAPIService) getSwaggerPbBytes() []byte {
+	return o.specPb
+}
+
+func (o *OpenAPIService) getSwaggerPbGzBytes() []byte {
+	return o.specPbGz
+}
+
+func (o *OpenAPIService) GetSpec() *spec.Swagger {
+	return o.orgSpec
+}
+
+func (o *OpenAPIService) UpdateSpec(openapiSpec *spec.Swagger) (err error) {
+	o.orgSpec = openapiSpec
+	o.specBytes, err = json.MarshalIndent(openapiSpec, " ", " ")
+	if err != nil {
+		return err
+	}
+	o.specPb, err = toProtoBinary(o.specBytes)
+	if err != nil {
+		return err
+	}
+	o.specPbGz = toGzip(o.specPb)
+	o.lastModified = time.Now()
+
+	return nil
+}
+
+func toProtoBinary(spec []byte) ([]byte, error) {
+	var info yaml.MapSlice
+	err := yaml.Unmarshal(spec, &info)
+	if err != nil {
+		return nil, err
+	}
+	document, err := openapi_v2.NewDocument(info, compiler.NewContext("$root", nil))
+	if err != nil {
+		return nil, err
+	}
+	return proto.Marshal(document)
+}
+
+func toGzip(data []byte) []byte {
+	var buf bytes.Buffer
+	zw := gzip.NewWriter(&buf)
+	zw.Write(data)
+	zw.Close()
+	return buf.Bytes()
+}
+
+// Adds an update hook to be called on each spec request. The hook is responsible
+// to call UpdateSpec method.
+func (o *OpenAPIService) AddUpdateHook(hook func(*http.Request)) {
+	o.updateHooks = append(o.updateHooks, hook)
+}
+
+func (o *OpenAPIService) update(r *http.Request) {
+	for _, h := range o.updateHooks {
+		h(r)
+	}
+}

staging/src/k8s.io/apiserver/pkg/server/routes/openapi.go

@@ -32,9 +32,16 @@ type OpenAPI struct {
 }
 
 // Install adds the SwaggerUI webservice to the given mux.
-func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) {
-	err := apiserveropenapi.RegisterOpenAPIService("/swagger.json", c.RegisteredWebServices(), oa.Config, mux)
+func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) *apiserveropenapi.OpenAPIService {
+	openapiSpec, err := apiserveropenapi.BuildSwaggerSpec(c.RegisteredWebServices(), oa.Config)
 	if err != nil {
 		glog.Fatalf("Failed to register open api spec for root: %v", err)
+		return nil
 	}
+	service, err := apiserveropenapi.RegisterOpenAPIService(openapiSpec, "/swagger.json", mux)
+	if err != nil {
+		glog.Fatalf("Failed to register open api spec for root: %v", err)
+		return nil
+	}
+	return service
 }