Apiextensions-apiserver aggregates CRD schemas

efficiently without checking conflicts, and wire up CRD discovery
controller to serve OpenAPI spec.

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

@@ -41,6 +41,7 @@ import (
 	"k8s.io/apiextensions-apiserver/pkg/controller/establish"
 	"k8s.io/apiextensions-apiserver/pkg/controller/finalizer"
 	"k8s.io/apiextensions-apiserver/pkg/controller/status"
+	openapiaggregator "k8s.io/apiextensions-apiserver/pkg/openapi"
 	"k8s.io/apiextensions-apiserver/pkg/registry/customresourcedefinition"
 
 	_ "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset"
@@ -204,7 +205,13 @@ func (c completedConfig) New(delegationTarget genericapiserver.DelegationTarget)
 		return nil
 	})
 	s.GenericAPIServer.AddPostStartHook("start-apiextensions-controllers", func(context genericapiserver.PostStartHookContext) error {
-		go crdController.Run(context.StopCh)
+		// create OpenAPI aggregation manager in the last step because only now genericapiserver's the OpenAPI services and spec is available (after PrepareRun).
+		crdOpenAPIAggregationManager, err := openapiaggregator.NewAggregationManager(s.GenericAPIServer.OpenAPIService, s.GenericAPIServer.OpenAPIVersionedService, s.GenericAPIServer.StaticOpenAPISpec)
+		if err != nil {
+			return err
+		}
+
+		go crdController.Run(context.StopCh, crdOpenAPIAggregationManager)
 		go namingController.Run(context.StopCh)
 		go establishingController.Run(context.StopCh)
 		go finalizingController.Run(5, context.StopCh)

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

@@ -31,12 +31,16 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apimachinery/pkg/version"
 	"k8s.io/apiserver/pkg/endpoints/discovery"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/util/workqueue"
 
 	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
+	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
 	informers "k8s.io/apiextensions-apiserver/pkg/client/informers/internalversion/apiextensions/internalversion"
 	listers "k8s.io/apiextensions-apiserver/pkg/client/listers/apiextensions/internalversion"
+	apiextensionsfeatures "k8s.io/apiextensions-apiserver/pkg/features"
+	apiextensionsopenapi "k8s.io/apiextensions-apiserver/pkg/openapi"
 )
 
 type DiscoveryController struct {
@@ -50,6 +54,8 @@ type DiscoveryController struct {
 	syncFn func(version schema.GroupVersion) error
 
 	queue workqueue.RateLimitingInterface
+
+	openAPIAggregationManager apiextensionsopenapi.AggregationManager
 }
 
 func NewDiscoveryController(crdInformer informers.CustomResourceDefinitionInformer, versionHandler *versionDiscoveryHandler, groupHandler *groupDiscoveryHandler) *DiscoveryController {
@@ -83,6 +89,7 @@ func (c *DiscoveryController) sync(version schema.GroupVersion) error {
 	if err != nil {
 		return err
 	}
+	apiServiceName := version.Group + "." + version.Version
 	foundVersion := false
 	foundGroup := false
 	for _, crd := range crds {
@@ -119,6 +126,33 @@ func (c *DiscoveryController) sync(version schema.GroupVersion) error {
 			continue
 		}
 		foundVersion = true
+		if c.openAPIAggregationManager != nil && utilfeature.DefaultFeatureGate.Enabled(apiextensionsfeatures.CustomResourceValidation) {
+			validationSchema, err := getSchemaForVersion(crd, version.Version)
+			if err != nil {
+				return err
+			}
+			// Convert internal CustomResourceValidation to versioned CustomResourceValidation
+			versionedSchema := new(v1beta1.CustomResourceValidation)
+			if validationSchema == nil {
+				versionedSchema = nil
+			} else {
+				if err := v1beta1.Convert_apiextensions_CustomResourceValidation_To_v1beta1_CustomResourceValidation(validationSchema, versionedSchema, nil); err != nil {
+					return err
+				}
+			}
+			// We aggregate the schema even if it's nil as it maybe a removal of the schema for this CRD,
+			// and the aggreated OpenAPI spec should reflect this change.
+			crdspec, etag, err := apiextensionsopenapi.CustomResourceDefinitionOpenAPISpec(&crd.Spec, version.Version, versionedSchema)
+			if err != nil {
+				return err
+			}
+
+			// Add/update the local API service's spec for the CRD in apiExtensionsServer's
+			// openAPIAggregationManager
+			if err := c.openAPIAggregationManager.AddUpdateLocalAPIServiceSpec(apiServiceName, crdspec, etag); err != nil {
+				return err
+			}
+		}
 
 		verbs := metav1.Verbs([]string{"delete", "deletecollection", "get", "list", "patch", "create", "update", "watch"})
 		// if we're terminating we don't allow some verbs
@@ -164,6 +198,14 @@ func (c *DiscoveryController) sync(version schema.GroupVersion) error {
 	if !foundGroup {
 		c.groupHandler.unsetDiscovery(version.Group)
 		c.versionHandler.unsetDiscovery(version)
+		if c.openAPIAggregationManager != nil && utilfeature.DefaultFeatureGate.Enabled(apiextensionsfeatures.CustomResourceValidation) {
+			// Remove the local API service for the CRD in apiExtensionsServer's
+			// openAPIAggregationManager.
+			// Note that we don't check if apiServiceName exists in openAPIAggregationManager
+			// because RemoveAPIServiceSpec properly handles non-existing API service by
+			// returning no error.
+			return c.openAPIAggregationManager.RemoveAPIServiceSpec(apiServiceName)
+		}
 		return nil
 	}
 
@@ -180,6 +222,14 @@ func (c *DiscoveryController) sync(version schema.GroupVersion) error {
 
 	if !foundVersion {
 		c.versionHandler.unsetDiscovery(version)
+		if c.openAPIAggregationManager != nil && utilfeature.DefaultFeatureGate.Enabled(apiextensionsfeatures.CustomResourceValidation) {
+			// Remove the local API service for the CRD in apiExtensionsServer's
+			// openAPIAggregationManager.
+			// Note that we don't check if apiServiceName exists in openAPIAggregationManager
+			// because RemoveAPIServiceSpec properly handles non-existing API service by
+			// returning no error.
+			return c.openAPIAggregationManager.RemoveAPIServiceSpec(apiServiceName)
+		}
 		return nil
 	}
 	c.versionHandler.setDiscovery(version, discovery.NewAPIVersionHandler(Codecs, version, discovery.APIResourceListerFunc(func() []metav1.APIResource {
@@ -195,13 +245,15 @@ func sortGroupDiscoveryByKubeAwareVersion(gd []metav1.GroupVersionForDiscovery)
 	})
 }
 
-func (c *DiscoveryController) Run(stopCh <-chan struct{}) {
+func (c *DiscoveryController) Run(stopCh <-chan struct{}, crdOpenAPIAggregationManager apiextensionsopenapi.AggregationManager) {
 	defer utilruntime.HandleCrash()
 	defer c.queue.ShutDown()
 	defer klog.Infof("Shutting down DiscoveryController")
 
 	klog.Infof("Starting DiscoveryController")
 
+	c.openAPIAggregationManager = crdOpenAPIAggregationManager
+
 	if !cache.WaitForCacheSync(stopCh, c.crdsSynced) {
 		utilruntime.HandleError(fmt.Errorf("timed out waiting for caches to sync"))
 		return

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

@@ -0,0 +1,232 @@
+/*
+Copyright 2018 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 (
+	"fmt"
+	"sync"
+
+	"github.com/go-openapi/spec"
+
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/kube-openapi/pkg/aggregator"
+	"k8s.io/kube-openapi/pkg/handler"
+)
+
+// AggregationManager is the interface between OpenAPI Aggregator service and a controller
+// that manages CRD openapi spec aggregation
+type AggregationManager interface {
+	// AddUpdateLocalAPIService allows adding/updating local API service with nil handler and
+	// nil Spec.Service. This function can be used for local dynamic OpenAPI spec aggregation
+	// management (e.g. CRD)
+	AddUpdateLocalAPIServiceSpec(name string, spec *spec.Swagger, etag string) error
+	RemoveAPIServiceSpec(apiServiceName string) error
+}
+
+type specAggregator struct {
+	// mutex protects all members of this struct.
+	rwMutex sync.RWMutex
+
+	// Map of API Services' OpenAPI specs by their name
+	openAPISpecs map[string]*openAPISpecInfo
+
+	// provided for dynamic OpenAPI spec
+	openAPIService          *handler.OpenAPIService
+	openAPIVersionedService *handler.OpenAPIService
+}
+
+var _ AggregationManager = &specAggregator{}
+
+// NewAggregationManager constructs a specAggregator from input openAPIService, openAPIVersionedService and
+// recorded static OpenAPI spec. The function returns an AggregationManager interface.
+func NewAggregationManager(openAPIService, openAPIVersionedService *handler.OpenAPIService, staticSpec *spec.Swagger) (AggregationManager, error) {
+	// openAPIVersionedService and deprecated openAPIService should be initialized together
+	if (openAPIService == nil) != (openAPIVersionedService == nil) {
+		return nil, fmt.Errorf("unexpected openapi service initialization error")
+	}
+	return &specAggregator{
+		openAPISpecs: map[string]*openAPISpecInfo{
+			"initial_static_spec": {
+				spec: staticSpec,
+			},
+		},
+		openAPIService:          openAPIService,
+		openAPIVersionedService: openAPIVersionedService,
+	}, nil
+}
+
+// openAPISpecInfo is used to store OpenAPI spec with its priority.
+// It can be used to sort specs with their priorities.
+type openAPISpecInfo struct {
+	// Name of a registered ApiService
+	name string
+
+	// Specification of this API Service. If null then the spec is not loaded yet.
+	spec *spec.Swagger
+	etag string
+}
+
+// buildOpenAPISpec aggregates all OpenAPI specs.  It is not thread-safe. The caller is responsible to hold proper locks.
+func (s *specAggregator) buildOpenAPISpec() (specToReturn *spec.Swagger, err error) {
+	specs := []openAPISpecInfo{}
+	for _, specInfo := range s.openAPISpecs {
+		if specInfo.spec == nil {
+			continue
+		}
+		specs = append(specs, *specInfo)
+	}
+	if len(specs) == 0 {
+		return &spec.Swagger{}, nil
+	}
+	for _, specInfo := range specs {
+		if specToReturn == nil {
+			specToReturn, err = aggregator.CloneSpec(specInfo.spec)
+			if err != nil {
+				return nil, err
+			}
+			continue
+		}
+		mergeSpecs(specToReturn, specInfo.spec)
+	}
+	// Add minimum required keys if missing, to properly serve the OpenAPI spec
+	// through apiextensions-apiserver HTTP handler. These keys will not be
+	// aggregated to top-level OpenAPI spec (only paths and definitions will).
+	// However these keys make the OpenAPI->proto serialization happy.
+	if specToReturn.Info == nil {
+		specToReturn.Info = &spec.Info{
+			InfoProps: spec.InfoProps{
+				Title: "Kubernetes",
+			},
+		}
+	}
+	if len(specToReturn.Swagger) == 0 {
+		specToReturn.Swagger = "2.0"
+	}
+	return specToReturn, nil
+}
+
+// updateOpenAPISpec aggregates all OpenAPI specs.  It is not thread-safe. The caller is responsible to hold proper locks.
+func (s *specAggregator) updateOpenAPISpec() error {
+	if s.openAPIService == nil || s.openAPIVersionedService == nil {
+		// openAPIVersionedService and deprecated openAPIService should be initialized together
+		if !(s.openAPIService == nil && s.openAPIVersionedService == nil) {
+			return fmt.Errorf("unexpected openapi service initialization error")
+		}
+		return nil
+	}
+	specToServe, err := s.buildOpenAPISpec()
+	if err != nil {
+		return err
+	}
+	// openAPIService.UpdateSpec and openAPIVersionedService.UpdateSpec read the same swagger spec
+	// serially and update their local caches separately. Both endpoints will have same spec in
+	// their caches if the caller is holding proper locks.
+	err = s.openAPIService.UpdateSpec(specToServe)
+	if err != nil {
+		return err
+	}
+	return s.openAPIVersionedService.UpdateSpec(specToServe)
+}
+
+// tryUpdatingServiceSpecs tries updating openAPISpecs map with specified specInfo, and keeps the map intact
+// if the update fails.
+func (s *specAggregator) tryUpdatingServiceSpecs(specInfo *openAPISpecInfo) error {
+	orgSpecInfo, exists := s.openAPISpecs[specInfo.name]
+	s.openAPISpecs[specInfo.name] = specInfo
+	if err := s.updateOpenAPISpec(); err != nil {
+		if exists {
+			s.openAPISpecs[specInfo.name] = orgSpecInfo
+		} else {
+			delete(s.openAPISpecs, specInfo.name)
+		}
+		return err
+	}
+	return nil
+}
+
+// tryDeleteServiceSpecs tries delete specified specInfo from openAPISpecs map, and keeps the map intact
+// if the update fails.
+func (s *specAggregator) tryDeleteServiceSpecs(apiServiceName string) error {
+	orgSpecInfo, exists := s.openAPISpecs[apiServiceName]
+	if !exists {
+		return nil
+	}
+	delete(s.openAPISpecs, apiServiceName)
+	if err := s.updateOpenAPISpec(); err != nil {
+		s.openAPISpecs[apiServiceName] = orgSpecInfo
+		return err
+	}
+	return nil
+}
+
+// AddUpdateLocalAPIService allows adding/updating local API service with nil handler and
+// nil Spec.Service. This function can be used for local dynamic OpenAPI spec aggregation
+// management (e.g. CRD)
+func (s *specAggregator) AddUpdateLocalAPIServiceSpec(name string, spec *spec.Swagger, etag string) error {
+	s.rwMutex.Lock()
+	defer s.rwMutex.Unlock()
+
+	return s.tryUpdatingServiceSpecs(&openAPISpecInfo{
+		name: name,
+		spec: spec,
+		etag: etag,
+	})
+}
+
+// RemoveAPIServiceSpec removes an api service from OpenAPI aggregation. If it does not exist, no error is returned.
+// It is thread safe.
+func (s *specAggregator) RemoveAPIServiceSpec(apiServiceName string) error {
+	s.rwMutex.Lock()
+	defer s.rwMutex.Unlock()
+
+	if _, existingService := s.openAPISpecs[apiServiceName]; !existingService {
+		return nil
+	}
+
+	return s.tryDeleteServiceSpecs(apiServiceName)
+}
+
+// mergeSpecs simply adds source openapi spec to dest and ignores any path/definition
+// conflicts because CRD openapi spec should not have conflict
+func mergeSpecs(dest, source *spec.Swagger) {
+	// Paths may be empty, due to [ACL constraints](http://goo.gl/8us55a#securityFiltering).
+	if source.Paths == nil {
+		// If Path is nil, none of the model defined in Definitions is used and we
+		// should not do anything.
+		// NOTE: this should not happen for CRD specs, because we automatically construct
+		// the Paths for CRD specs. We use utilruntime.HandleError to log this impossible
+		// case
+		utilruntime.HandleError(fmt.Errorf("unexpected CRD spec with empty Path: %v", *source))
+		return
+	}
+	if dest.Paths == nil {
+		dest.Paths = &spec.Paths{}
+	}
+	for k, v := range source.Definitions {
+		if dest.Definitions == nil {
+			dest.Definitions = spec.Definitions{}
+		}
+		dest.Definitions[k] = v
+	}
+	for k, v := range source.Paths.Paths {
+		// PathItem may be empty, due to [ACL constraints](http://goo.gl/8us55a#securityFiltering).
+		if dest.Paths.Paths == nil {
+			dest.Paths.Paths = map[string]spec.PathItem{}
+		}
+		dest.Paths.Paths[k] = v
+	}
+}

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

@@ -25,7 +25,8 @@ import (
 	"time"
 
 	systemd "github.com/coreos/go-systemd/daemon"
-	"github.com/emicklei/go-restful-swagger12"
+	swagger "github.com/emicklei/go-restful-swagger12"
+	"github.com/go-openapi/spec"
 	"k8s.io/klog"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -47,6 +48,7 @@ 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"
 )
@@ -124,6 +126,11 @@ type GenericAPIServer struct {
 	swaggerConfig *swagger.Config
 	openAPIConfig *openapicommon.Config
 
+	// Expose the registered OpenAPI Services and built static OpenAPI spec if openAPIConfig is non-nil
+	OpenAPIService          *handler.OpenAPIService // for endpoint /swagger.json
+	OpenAPIVersionedService *handler.OpenAPIService // for endpoint /openapi/v2
+	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.
@@ -240,7 +247,7 @@ func (s *GenericAPIServer) PrepareRun() preparedGenericAPIServer {
 		routes.Swagger{Config: s.swaggerConfig}.Install(s.Handler.GoRestfulContainer)
 	}
 	if s.openAPIConfig != nil {
-		routes.OpenAPI{
+		s.OpenAPIService, s.OpenAPIVersionedService, s.StaticOpenAPISpec = routes.OpenAPI{
 			Config: s.openAPIConfig,
 		}.Install(s.Handler.GoRestfulContainer, s.Handler.NonGoRestfulMux)
 	}

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"
 )
@@ -30,17 +32,27 @@ type OpenAPI struct {
 	Config *common.Config
 }
 
-// Install adds the SwaggerUI webservice to the given mux.
-func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) {
+// Install adds the SwaggerUI webservice to the given mux. This function returns
+// the built static OpenAPI spec and the registered OpenAPI services to allow
+// further OpenAPI spec aggregation.
+func (oa OpenAPI) Install(c *restful.Container, mux *mux.PathRecorderMux) (openAPIService, openAPIVersionedService *handler.OpenAPIService, spec *spec.Swagger) {
+	var err error
+	// Record the static OpenAPI spec to allow further OpenAPI spec aggregation
+	// with this static spec on the registered OpenAPI services
+	spec, err = builder.BuildOpenAPISpec(c.RegisteredWebServices(), oa.Config)
+	if err != nil {
+		klog.Fatalf("Failed to build open api spec for root: %v", err)
+	}
 	// NOTE: [DEPRECATION] We will announce deprecation for format-separated endpoints for OpenAPI spec,
 	// and switch to a single /openapi/v2 endpoint in Kubernetes 1.10. The design doc and deprecation process
 	// are tracked at: https://docs.google.com/document/d/19lEqE9lc4yHJ3WJAJxS_G7TcORIJXGHyq3wpwcH28nU.
-	_, err := handler.BuildAndRegisterOpenAPIService("/swagger.json", c.RegisteredWebServices(), oa.Config, mux)
+	openAPIService, err = handler.RegisterOpenAPIService(spec, "/swagger.json", mux)
 	if err != nil {
 		klog.Fatalf("Failed to register open api spec for root: %v", err)
 	}
-	_, err = handler.BuildAndRegisterOpenAPIVersionedService("/openapi/v2", c.RegisteredWebServices(), oa.Config, mux)
+	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 openAPIService, openAPIVersionedService, spec
 }