allow fallthrough handling from go-restful routes

federation/cmd/federation-apiserver/app/server.go

@@ -223,7 +223,7 @@ func NonBlockingRun(s *options.ServerRunOptions, stopCh <-chan struct{}) error {
 		return err
 	}
 
-	routes.UIRedirect{}.Install(m.HandlerContainer)
+	routes.UIRedirect{}.Install(m.FallThroughHandler)
 	routes.Logs{}.Install(m.HandlerContainer)
 
 	installFederationAPIs(m, genericConfig.RESTOptionsGetter)

pkg/master/master.go

@@ -216,7 +216,7 @@ func (c completedConfig) New() (*Master, error) {
 	}
 
 	if c.EnableUISupport {
-		routes.UIRedirect{}.Install(s.HandlerContainer)
+		routes.UIRedirect{}.Install(s.FallThroughHandler)
 	}
 	if c.EnableLogsSupport {
 		routes.Logs{}.Install(s.HandlerContainer)

pkg/master/master_openapi_test.go

@@ -40,7 +40,7 @@ import (
 // TestValidOpenAPISpec verifies that the open api is added
 // at the proper endpoint and the spec is valid.
 func TestValidOpenAPISpec(t *testing.T) {
-	_, etcdserver, config, assert := setUp(t)
+	etcdserver, config, assert := setUp(t)
 	defer etcdserver.Terminate(t)
 
 	config.GenericConfig.EnableIndex = true

pkg/master/master_test.go

@@ -60,7 +60,7 @@ import (
 )
 
 // setUp is a convience function for setting up for (most) tests.
-func setUp(t *testing.T) (*Master, *etcdtesting.EtcdTestServer, Config, *assert.Assertions) {
+func setUp(t *testing.T) (*etcdtesting.EtcdTestServer, Config, *assert.Assertions) {
 	server, storageConfig := etcdtesting.NewUnsecuredEtcd3TestClientServer(t, api.Scheme)
 
 	config := &Config{
@@ -101,16 +101,11 @@ func setUp(t *testing.T) (*Master, *etcdtesting.EtcdTestServer, Config, *assert.
 		TLSClientConfig: &tls.Config{},
 	})
 
-	master, err := config.Complete().New()
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	return master, server, *config, assert.New(t)
+	return server, *config, assert.New(t)
 }
 
 func newMaster(t *testing.T) (*Master, *etcdtesting.EtcdTestServer, Config, *assert.Assertions) {
-	_, etcdserver, config, assert := setUp(t)
+	etcdserver, config, assert := setUp(t)
 
 	master, err := config.Complete().New()
 	if err != nil {
@@ -136,7 +131,7 @@ func limitedAPIResourceConfigSource() *serverstorage.ResourceConfig {
 
 // newLimitedMaster only enables the core group, the extensions group, the batch group, and the autoscaling group.
 func newLimitedMaster(t *testing.T) (*Master, *etcdtesting.EtcdTestServer, Config, *assert.Assertions) {
-	_, etcdserver, config, assert := setUp(t)
+	etcdserver, config, assert := setUp(t)
 	config.APIResourceConfigSource = limitedAPIResourceConfigSource()
 	master, err := config.Complete().New()
 	if err != nil {

pkg/routes/ui.go

@@ -27,8 +27,8 @@ const dashboardPath = "/api/v1/namespaces/kube-system/services/kubernetes-dashbo
 // UIRediect redirects /ui to the kube-ui proxy path.
 type UIRedirect struct{}
 
-func (r UIRedirect) Install(c *mux.APIContainer) {
-	c.NonSwaggerRoutes.HandleFunc("/ui/", func(w http.ResponseWriter, r *http.Request) {
+func (r UIRedirect) Install(c *mux.PathRecorderMux) {
+	c.HandleFunc("/ui/", func(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, dashboardPath, http.StatusTemporaryRedirect)
 	})
 }

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

@@ -107,6 +107,10 @@ type Config struct {
 	// Will default to a value based on secure serving info and available ipv4 IPs.
 	ExternalAddress string
 
+	// FallThroughHandler is the final HTTP handler in the chain.  If it is nil, one will be created for you.
+	// It comes after all filters and the API handling
+	FallThroughHandler *mux.PathRecorderMux
+
 	//===========================================================================
 	// Fields you probably don't care about changing
 	//===========================================================================
@@ -337,6 +341,9 @@ func (c *Config) Complete() completedConfig {
 		tokenAuthorizer := authorizerfactory.NewPrivilegedGroups(user.SystemPrivilegedGroup)
 		c.Authorizer = authorizerunion.New(tokenAuthorizer, c.Authorizer)
 	}
+	if c.FallThroughHandler == nil {
+		c.FallThroughHandler = mux.NewPathRecorderMux()
+	}
 
 	return completedConfig{c}
 }
@@ -392,6 +399,8 @@ func (c completedConfig) New() (*GenericAPIServer, error) {
 
 		apiGroupsForDiscovery: map[string]metav1.APIGroup{},
 
+		FallThroughHandler: c.FallThroughHandler,
+
 		swaggerConfig: c.SwaggerConfig,
 		openAPIConfig: c.OpenAPIConfig,
 
@@ -399,7 +408,7 @@ func (c completedConfig) New() (*GenericAPIServer, error) {
 		healthzChecks:  c.HealthzChecks,
 	}
 
-	s.HandlerContainer = mux.NewAPIContainer(http.NewServeMux(), c.Serializer)
+	s.HandlerContainer = mux.NewAPIContainer(http.NewServeMux(), c.Serializer, s.FallThroughHandler)
 
 	if s.openAPIConfig != nil {
 		if s.openAPIConfig.Info == nil {
@@ -447,22 +456,22 @@ func DefaultBuildHandlerChain(apiHandler http.Handler, c *Config) (secure, insec
 
 func (s *GenericAPIServer) installAPI(c *Config) {
 	if c.EnableIndex {
-		routes.Index{}.Install(s.HandlerContainer)
+		routes.Index{}.Install(s.HandlerContainer, s.FallThroughHandler)
 	}
 	if c.SwaggerConfig != nil && c.EnableSwaggerUI {
-		routes.SwaggerUI{}.Install(s.HandlerContainer)
+		routes.SwaggerUI{}.Install(s.FallThroughHandler)
 	}
 	if c.EnableProfiling {
-		routes.Profiling{}.Install(s.HandlerContainer)
+		routes.Profiling{}.Install(s.FallThroughHandler)
 		if c.EnableContentionProfiling {
 			goruntime.SetBlockProfileRate(1)
 		}
 	}
 	if c.EnableMetrics {
 		if c.EnableProfiling {
-			routes.MetricsWithReset{}.Install(s.HandlerContainer)
+			routes.MetricsWithReset{}.Install(s.FallThroughHandler)
 		} else {
-			routes.DefaultMetrics{}.Install(s.HandlerContainer)
+			routes.DefaultMetrics{}.Install(s.FallThroughHandler)
 		}
 	}
 	routes.Version{Version: c.Version}.Install(s.HandlerContainer)

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

@@ -44,6 +44,7 @@ import (
 	apirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/apiserver/pkg/registry/rest"
 	"k8s.io/apiserver/pkg/server/healthz"
+	"k8s.io/apiserver/pkg/server/mux"
 	genericmux "k8s.io/apiserver/pkg/server/mux"
 	"k8s.io/apiserver/pkg/server/routes"
 	restclient "k8s.io/client-go/rest"
@@ -125,6 +126,9 @@ type GenericAPIServer struct {
 	// "Outputs"
 	Handler         http.Handler
 	InsecureHandler http.Handler
+	// FallThroughHandler is the final HTTP handler in the chain.
+	// It comes after all filters and the API handling
+	FallThroughHandler *mux.PathRecorderMux
 
 	// Map storing information about all groups to be exposed in discovery response.
 	// The map is from name to the group.
@@ -179,7 +183,7 @@ func (s *GenericAPIServer) PrepareRun() preparedGenericAPIServer {
 	if s.openAPIConfig != nil {
 		routes.OpenAPI{
 			Config: s.openAPIConfig,
-		}.Install(s.HandlerContainer)
+		}.Install(s.HandlerContainer, s.FallThroughHandler)
 	}
 
 	s.installHealthz()

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

@@ -48,6 +48,7 @@ import (
 	"k8s.io/apiserver/pkg/authorization/authorizer"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/apiserver/pkg/registry/rest"
+	"k8s.io/apiserver/pkg/server/mux"
 	etcdtesting "k8s.io/apiserver/pkg/storage/etcd/testing"
 	restclient "k8s.io/client-go/rest"
 )
@@ -90,6 +91,7 @@ func setUp(t *testing.T) (*etcdtesting.EtcdTestServer, Config, *assert.Assertion
 	config.RequestContextMapper = genericapirequest.NewRequestContextMapper()
 	config.LegacyAPIGroupPrefixes = sets.NewString("/api")
 	config.LoopbackClientConfig = &restclient.Config{}
+	config.FallThroughHandler = mux.NewPathRecorderMux()
 
 	// TODO restore this test, but right now, eliminate our cycle
 	// config.OpenAPIConfig = DefaultOpenAPIConfig(testGetOpenAPIDefinitions, runtime.NewScheme())
@@ -352,8 +354,8 @@ func TestCustomHandlerChain(t *testing.T) {
 		t.Fatalf("Error in bringing up the server: %v", err)
 	}
 
-	s.HandlerContainer.NonSwaggerRoutes.Handle("/nonswagger", handler)
-	s.HandlerContainer.UnlistedRoutes.Handle("/secret", handler)
+	s.FallThroughHandler.Handle("/nonswagger", handler)
+	s.FallThroughHandler.Handle("/secret", handler)
 
 	type Test struct {
 		handler   http.Handler

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

@@ -41,5 +41,5 @@ func (s *GenericAPIServer) installHealthz() {
 	defer s.healthzLock.Unlock()
 	s.healthzCreated = true
 
-	healthz.InstallHandler(&s.HandlerContainer.NonSwaggerRoutes, s.healthzChecks...)
+	healthz.InstallHandler(s.FallThroughHandler, s.healthzChecks...)
 }

staging/src/k8s.io/apiserver/pkg/server/mux/container.go

@@ -35,22 +35,12 @@ import (
 // handlers that do not show up in swagger or in /
 type APIContainer struct {
 	*restful.Container
-
-	// NonSwaggerRoutes are recorded and are visible at /, but do not show up in Swagger.
-	NonSwaggerRoutes PathRecorderMux
-
-	// UnlistedRoutes are not recorded, therefore not visible at / and do not show up in Swagger.
-	UnlistedRoutes *http.ServeMux
 }
 
 // NewAPIContainer constructs a new container for APIs
-func NewAPIContainer(mux *http.ServeMux, s runtime.NegotiatedSerializer) *APIContainer {
+func NewAPIContainer(mux *http.ServeMux, s runtime.NegotiatedSerializer, defaultMux http.Handler) *APIContainer {
 	c := APIContainer{
 		Container: restful.NewContainer(),
-		NonSwaggerRoutes: PathRecorderMux{
-			mux: mux,
-		},
-		UnlistedRoutes: mux,
 	}
 	c.Container.ServeMux = mux
 	c.Container.Router(restful.CurlyRouter{}) // e.g. for proxy/{kind}/{name}/{*}
@@ -61,6 +51,10 @@ func NewAPIContainer(mux *http.ServeMux, s runtime.NegotiatedSerializer) *APICon
 		serviceErrorHandler(s, serviceErr, request, response)
 	})
 
+	// register the defaultHandler for everything.  This will allow an unhandled request to fall through to another handler instead of
+	// ending up with a forced 404
+	c.Container.Handle("/", defaultMux)
+
 	return &c
 }
 

staging/src/k8s.io/apiserver/pkg/server/mux/pathrecorder.go

@@ -17,47 +17,83 @@ limitations under the License.
 package mux
 
 import (
+	"fmt"
 	"net/http"
-)
+	"runtime/debug"
 
-// Mux is an object that can register http handlers.
-type Mux interface {
-	Handle(pattern string, handler http.Handler)
-	HandleFunc(pattern string, handler func(http.ResponseWriter, *http.Request))
-}
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+)
 
-// PathRecorderMux wraps a mux object and records the registered paths. It is _not_ go routine safe.
+// PathRecorderMux wraps a mux object and records the registered exposedPaths. It is _not_ go routine safe.
 type PathRecorderMux struct {
-	mux   Mux
-	paths []string
+	mux          *http.ServeMux
+	exposedPaths []string
+
+	// pathStacks holds the stacks of all registered paths.  This allows us to show a more helpful message
+	// before the "http: multiple registrations for %s" panic.
+	pathStacks map[string]string
 }
 
 // NewPathRecorderMux creates a new PathRecorderMux with the given mux as the base mux.
-func NewPathRecorderMux(mux Mux) *PathRecorderMux {
+func NewPathRecorderMux() *PathRecorderMux {
 	return &PathRecorderMux{
-		mux: mux,
+		mux:        http.NewServeMux(),
+		pathStacks: map[string]string{},
 	}
 }
 
-// BaseMux returns the underlying mux.
-func (m *PathRecorderMux) BaseMux() Mux {
-	return m.mux
-}
-
-// HandledPaths returns the registered handler paths.
+// HandledPaths returns the registered handler exposedPaths.
 func (m *PathRecorderMux) HandledPaths() []string {
-	return append([]string{}, m.paths...)
+	return append([]string{}, m.exposedPaths...)
 }
 
 // Handle registers the handler for the given pattern.
 // If a handler already exists for pattern, Handle panics.
 func (m *PathRecorderMux) Handle(path string, handler http.Handler) {
-	m.paths = append(m.paths, path)
+	if existingStack, ok := m.pathStacks[path]; ok {
+		utilruntime.HandleError(fmt.Errorf("registered %q from %v", path, existingStack))
+	}
+	m.pathStacks[path] = string(debug.Stack())
+
+	m.exposedPaths = append(m.exposedPaths, path)
 	m.mux.Handle(path, handler)
 }
 
 // HandleFunc registers the handler function for the given pattern.
+// If a handler already exists for pattern, Handle panics.
 func (m *PathRecorderMux) HandleFunc(path string, handler func(http.ResponseWriter, *http.Request)) {
-	m.paths = append(m.paths, path)
+	if existingStack, ok := m.pathStacks[path]; ok {
+		utilruntime.HandleError(fmt.Errorf("registered %q from %v", path, existingStack))
+	}
+	m.pathStacks[path] = string(debug.Stack())
+
+	m.exposedPaths = append(m.exposedPaths, path)
 	m.mux.HandleFunc(path, handler)
 }
+
+// UnlistedHandle registers the handler for the given pattern, but doesn't list it.
+// If a handler already exists for pattern, Handle panics.
+func (m *PathRecorderMux) UnlistedHandle(path string, handler http.Handler) {
+	if existingStack, ok := m.pathStacks[path]; ok {
+		utilruntime.HandleError(fmt.Errorf("registered %q from %v", path, existingStack))
+	}
+	m.pathStacks[path] = string(debug.Stack())
+	m.mux.Handle(path, handler)
+
+}
+
+// UnlistedHandleFunc registers the handler function for the given pattern, but doesn't list it.
+// If a handler already exists for pattern, Handle panics.
+func (m *PathRecorderMux) UnlistedHandleFunc(path string, handler func(http.ResponseWriter, *http.Request)) {
+	if existingStack, ok := m.pathStacks[path]; ok {
+		utilruntime.HandleError(fmt.Errorf("registered %q from %v", path, existingStack))
+	}
+	m.pathStacks[path] = string(debug.Stack())
+
+	m.mux.HandleFunc(path, handler)
+}
+
+// ServeHTTP makes it an http.Handler
+func (m *PathRecorderMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	m.mux.ServeHTTP(w, r)
+}

staging/src/k8s.io/apiserver/pkg/server/mux/container_test.go → staging/src/k8s.io/apiserver/pkg/server/mux/pathrecorder_test.go

@@ -23,18 +23,10 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestNewAPIContainer(t *testing.T) {
-	mux := http.NewServeMux()
-	c := NewAPIContainer(mux, nil)
-	assert.Equal(t, mux, c.UnlistedRoutes, "UnlistedRoutes ServeMux's do not match")
-	assert.Equal(t, mux, c.Container.ServeMux, "Container ServeMux's do not match")
-}
-
 func TestSecretHandlers(t *testing.T) {
-	mux := http.NewServeMux()
-	c := NewAPIContainer(mux, nil)
-	c.UnlistedRoutes.HandleFunc("/secret", func(http.ResponseWriter, *http.Request) {})
-	c.NonSwaggerRoutes.HandleFunc("/nonswagger", func(http.ResponseWriter, *http.Request) {})
-	assert.NotContains(t, c.NonSwaggerRoutes.HandledPaths(), "/secret")
-	assert.Contains(t, c.NonSwaggerRoutes.HandledPaths(), "/nonswagger")
+	c := NewPathRecorderMux()
+	c.UnlistedHandleFunc("/secret", func(http.ResponseWriter, *http.Request) {})
+	c.HandleFunc("/nonswagger", func(http.ResponseWriter, *http.Request) {})
+	assert.NotContains(t, c.HandledPaths(), "/secret")
+	assert.Contains(t, c.HandledPaths(), "/nonswagger")
 }

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

@@ -44,7 +44,7 @@ type openAPI struct {
 }
 
 // RegisterOpenAPIService registers a handler to provides standard OpenAPI specification.
-func RegisterOpenAPIService(servePath string, webServices []*restful.WebService, config *openapi.Config, container *genericmux.APIContainer) (err error) {
+func RegisterOpenAPIService(servePath string, webServices []*restful.WebService, config *openapi.Config, mux *genericmux.PathRecorderMux) (err error) {
 	o := openAPI{
 		config:    config,
 		servePath: servePath,
@@ -63,7 +63,7 @@ func RegisterOpenAPIService(servePath string, webServices []*restful.WebService,
 		return err
 	}
 
-	container.UnlistedRoutes.HandleFunc(servePath, func(w http.ResponseWriter, r *http.Request) {
+	mux.UnlistedHandleFunc(servePath, func(w http.ResponseWriter, r *http.Request) {
 		resp := restful.NewResponse(w)
 		if r.URL.Path != servePath {
 			resp.WriteErrorString(http.StatusNotFound, "Path not found!")

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

@@ -29,8 +29,8 @@ import (
 type Index struct{}
 
 // Install adds the Index webservice to the given mux.
-func (i Index) Install(c *mux.APIContainer) {
-	c.UnlistedRoutes.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+func (i Index) Install(c *mux.APIContainer, mux *mux.PathRecorderMux) {
+	mux.UnlistedHandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		status := http.StatusOK
 		if r.URL.Path != "/" && r.URL.Path != "/index.html" {
 			// Since "/" matches all paths, handleIndex is called for all paths for which there is no handler api.Registry.
@@ -43,7 +43,7 @@ func (i Index) Install(c *mux.APIContainer) {
 			handledPaths = append(handledPaths, ws.RootPath())
 		}
 		// Extract the paths handled using mux handler.
-		handledPaths = append(handledPaths, c.NonSwaggerRoutes.HandledPaths()...)
+		handledPaths = append(handledPaths, mux.HandledPaths()...)
 		sort.Strings(handledPaths)
 		responsewriters.WriteRawJSON(status, metav1.RootPaths{Paths: handledPaths}, w)
 	})

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

@@ -31,8 +31,8 @@ import (
 type DefaultMetrics struct{}
 
 // Install adds the DefaultMetrics handler
-func (m DefaultMetrics) Install(c *mux.APIContainer) {
-	c.NonSwaggerRoutes.Handle("/metrics", prometheus.Handler())
+func (m DefaultMetrics) Install(c *mux.PathRecorderMux) {
+	c.Handle("/metrics", prometheus.Handler())
 }
 
 // MetricsWithReset install the prometheus metrics handler extended with support for the DELETE method
@@ -40,9 +40,9 @@ func (m DefaultMetrics) Install(c *mux.APIContainer) {
 type MetricsWithReset struct{}
 
 // Install adds the MetricsWithReset handler
-func (m MetricsWithReset) Install(c *mux.APIContainer) {
+func (m MetricsWithReset) Install(c *mux.PathRecorderMux) {
 	defaultMetricsHandler := prometheus.Handler().ServeHTTP
-	c.NonSwaggerRoutes.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
+	c.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
 		if req.Method == "DELETE" {
 			apimetrics.Reset()
 			etcdmetrics.Reset()

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

@@ -30,8 +30,8 @@ type OpenAPI struct {
 }
 
 // Install adds the SwaggerUI webservice to the given mux.
-func (oa OpenAPI) Install(c *mux.APIContainer) {
-	err := apiserveropenapi.RegisterOpenAPIService("/swagger.json", c.RegisteredWebServices(), oa.Config, c)
+func (oa OpenAPI) Install(c *mux.APIContainer, mux *mux.PathRecorderMux) {
+	err := apiserveropenapi.RegisterOpenAPIService("/swagger.json", c.RegisteredWebServices(), oa.Config, mux)
 	if err != nil {
 		glog.Fatalf("Failed to register open api spec for root: %v", err)
 	}

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

@@ -26,9 +26,9 @@ import (
 type Profiling struct{}
 
 // Install adds the Profiling webservice to the given mux.
-func (d Profiling) Install(c *mux.APIContainer) {
-	c.UnlistedRoutes.HandleFunc("/debug/pprof/", pprof.Index)
-	c.UnlistedRoutes.HandleFunc("/debug/pprof/profile", pprof.Profile)
-	c.UnlistedRoutes.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
-	c.UnlistedRoutes.HandleFunc("/debug/pprof/trace", pprof.Trace)
+func (d Profiling) Install(c *mux.PathRecorderMux) {
+	c.UnlistedHandleFunc("/debug/pprof/", pprof.Index)
+	c.UnlistedHandleFunc("/debug/pprof/profile", pprof.Profile)
+	c.UnlistedHandleFunc("/debug/pprof/symbol", pprof.Symbol)
+	c.UnlistedHandleFunc("/debug/pprof/trace", pprof.Trace)
 }

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

@@ -29,12 +29,12 @@ import (
 type SwaggerUI struct{}
 
 // Install adds the SwaggerUI webservice to the given mux.
-func (l SwaggerUI) Install(c *mux.APIContainer) {
+func (l SwaggerUI) Install(c *mux.PathRecorderMux) {
 	fileServer := http.FileServer(&assetfs.AssetFS{
 		Asset:    swagger.Asset,
 		AssetDir: swagger.AssetDir,
 		Prefix:   "third_party/swagger-ui",
 	})
 	prefix := "/swagger-ui/"
-	c.NonSwaggerRoutes.Handle(prefix, http.StripPrefix(prefix, fileServer))
+	c.Handle(prefix, http.StripPrefix(prefix, fileServer))
 }

staging/src/k8s.io/kube-aggregator/pkg/apiserver/apiserver.go

@@ -250,8 +250,8 @@ func (s *APIAggregator) AddAPIService(apiService *apiregistration.APIService) {
 		endpointsLister: s.endpointsLister,
 	}
 	// aggregation is protected
-	s.GenericAPIServer.HandlerContainer.UnlistedRoutes.Handle(groupPath, groupDiscoveryHandler)
-	s.GenericAPIServer.HandlerContainer.UnlistedRoutes.Handle(groupPath+"/", groupDiscoveryHandler)
+	s.GenericAPIServer.FallThroughHandler.UnlistedHandle(groupPath, groupDiscoveryHandler)
+	s.GenericAPIServer.FallThroughHandler.UnlistedHandle(groupPath+"/", groupDiscoveryHandler)
 	s.handledGroups.Insert(apiService.Spec.Group)
 }
 

vendor/BUILD

@@ -10488,6 +10488,7 @@ go_test(
         "//vendor:k8s.io/apiserver/pkg/authorization/authorizer",
         "//vendor:k8s.io/apiserver/pkg/endpoints/request",
         "//vendor:k8s.io/apiserver/pkg/registry/rest",
+        "//vendor:k8s.io/apiserver/pkg/server/mux",
         "//vendor:k8s.io/apiserver/pkg/storage/etcd/testing",
         "//vendor:k8s.io/client-go/rest",
     ],
@@ -10627,7 +10628,7 @@ go_library(
 
 go_test(
     name = "k8s.io/apiserver/pkg/server/mux_test",
-    srcs = ["k8s.io/apiserver/pkg/server/mux/container_test.go"],
+    srcs = ["k8s.io/apiserver/pkg/server/mux/pathrecorder_test.go"],
     library = ":k8s.io/apiserver/pkg/server/mux",
     tags = ["automanaged"],
     deps = ["//vendor:github.com/stretchr/testify/assert"],
@@ -10647,6 +10648,7 @@ go_library(
         "//vendor:k8s.io/apimachinery/pkg/api/errors",
         "//vendor:k8s.io/apimachinery/pkg/runtime",
         "//vendor:k8s.io/apimachinery/pkg/runtime/schema",
+        "//vendor:k8s.io/apimachinery/pkg/util/runtime",
         "//vendor:k8s.io/apiserver/pkg/endpoints/handlers/responsewriters",
     ],
 )