genericapiserver: expose openapi service to allow updating the served spec

staging/src/k8s.io/apiserver/pkg/server/BUILD

@@ -115,6 +115,7 @@ go_library(
         "//vendor/k8s.io/klog:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/builder:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/common:go_default_library",
+        "//vendor/k8s.io/kube-openapi/pkg/handler:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/util:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/util/proto:go_default_library",
     ],

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

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	systemd "github.com/coreos/go-systemd/daemon"
+	"github.com/go-openapi/spec"
 	"k8s.io/klog"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -46,6 +47,7 @@ import (
 	restclient "k8s.io/client-go/rest"
 	openapibuilder "k8s.io/kube-openapi/pkg/builder"
 	openapicommon "k8s.io/kube-openapi/pkg/common"
+	"k8s.io/kube-openapi/pkg/handler"
 	openapiutil "k8s.io/kube-openapi/pkg/util"
 	openapiproto "k8s.io/kube-openapi/pkg/util/proto"
 )
@@ -122,6 +124,14 @@ type GenericAPIServer struct {
 	// Enable swagger and/or OpenAPI if these configs are non-nil.
 	openAPIConfig *openapicommon.Config
 
+	// OpenAPIVersionedService controls the /openapi/v2 endpoint, and can be used to update the served spec.
+	// It is set during PrepareRun.
+	OpenAPIVersionedService *handler.OpenAPIService
+
+	// StaticOpenAPISpec is the spec derived from the restful container endpoints.
+	// It is set during PrepareRun.
+	StaticOpenAPISpec *spec.Swagger
+
 	// PostStartHooks are each called after the server has started listening, in a separate go func for each
 	// with no guarantee of ordering between them.  The map key is a name used for error reporting.
 	// It may kill the process with a panic if it wishes to by returning an error.
@@ -239,7 +249,7 @@ type preparedGenericAPIServer struct {
 // PrepareRun does post API installation setup steps.
 func (s *GenericAPIServer) PrepareRun() preparedGenericAPIServer {
 	if s.openAPIConfig != nil {
-		routes.OpenAPI{
+		s.OpenAPIVersionedService, s.StaticOpenAPISpec = routes.OpenAPI{
 			Config: s.openAPIConfig,
 		}.Install(s.Handler.GoRestfulContainer, s.Handler.NonGoRestfulMux)
 	}

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

@@ -31,6 +31,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/go-openapi/spec"
 	openapi "github.com/go-openapi/spec"
 	"github.com/stretchr/testify/assert"
 
@@ -338,6 +339,46 @@ func TestPrepareRun(t *testing.T) {
 	assert.Equal(http.StatusOK, resp.StatusCode)
 }
 
+func TestUpdateOpenAPISpec(t *testing.T) {
+	s, _, assert := newMaster(t)
+	s.PrepareRun()
+	s.RunPostStartHooks(make(chan struct{}))
+
+	server := httptest.NewServer(s.Handler.Director)
+	defer server.Close()
+
+	// verify the static spec in record is what we currently serve
+	oldSpec, err := json.Marshal(s.StaticOpenAPISpec)
+	assert.NoError(err)
+
+	resp, err := http.Get(server.URL + "/openapi/v2")
+	assert.NoError(err)
+	assert.Equal(http.StatusOK, resp.StatusCode)
+
+	body, err := ioutil.ReadAll(resp.Body)
+	assert.NoError(err)
+	assert.Equal(oldSpec, body)
+	resp.Body.Close()
+
+	// verify we are able to update the served spec using the exposed service
+	newSpec := []byte(`{"swagger":"2.0","info":{"title":"Test Updated Generic API Server Swagger","version":"v0.1.0"},"paths":null}`)
+	swagger := new(spec.Swagger)
+	err = json.Unmarshal(newSpec, swagger)
+	assert.NoError(err)
+
+	err = s.OpenAPIVersionedService.UpdateSpec(swagger)
+	assert.NoError(err)
+
+	resp, err = http.Get(server.URL + "/openapi/v2")
+	assert.NoError(err)
+	defer resp.Body.Close()
+	assert.Equal(http.StatusOK, resp.StatusCode)
+
+	body, err = ioutil.ReadAll(resp.Body)
+	assert.NoError(err)
+	assert.Equal(newSpec, body)
+}
+
 // TestCustomHandlerChain verifies the handler chain with custom handler chain builder functions.
 func TestCustomHandlerChain(t *testing.T) {
 	config, _ := setUp(t)

staging/src/k8s.io/apiserver/pkg/server/routes/BUILD

@@ -27,8 +27,10 @@ go_library(
         "//staging/src/k8s.io/apiserver/pkg/server/mux:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/etcd/metrics:go_default_library",
         "//vendor/github.com/emicklei/go-restful:go_default_library",
+        "//vendor/github.com/go-openapi/spec:go_default_library",
         "//vendor/github.com/prometheus/client_golang/prometheus:go_default_library",
         "//vendor/k8s.io/klog:go_default_library",
+        "//vendor/k8s.io/kube-openapi/pkg/builder:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/common:go_default_library",
         "//vendor/k8s.io/kube-openapi/pkg/handler:go_default_library",
     ],

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

@@ -18,9 +18,11 @@ package routes
 
 import (
 	restful "github.com/emicklei/go-restful"
+	"github.com/go-openapi/spec"
 	"k8s.io/klog"
 
 	"k8s.io/apiserver/pkg/server/mux"
+	"k8s.io/kube-openapi/pkg/builder"
 	"k8s.io/kube-openapi/pkg/common"
 	"k8s.io/kube-openapi/pkg/handler"
 )
@@ -31,9 +33,14 @@ type OpenAPI struct {
 }
 
 // Install adds the SwaggerUI webservice to the given mux.
-func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) {
-	_, err := handler.BuildAndRegisterOpenAPIVersionedService("/openapi/v2", c.RegisteredWebServices(), oa.Config, mux)
+func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) (*handler.OpenAPIService, *spec.Swagger) {
+	spec, err := builder.BuildOpenAPISpec(c.RegisteredWebServices(), oa.Config)
+	if err != nil {
+		klog.Fatalf("Failed to build open api spec for root: %v", err)
+	}
+	openAPIVersionedService, err := handler.RegisterOpenAPIVersionedService(spec, "/openapi/v2", mux)
 	if err != nil {
 		klog.Fatalf("Failed to register versioned open api spec for root: %v", err)
 	}
+	return openAPIVersionedService, spec
 }