add ability to pre-configure poststarthooks for apiservers

cmd/kube-apiserver/app/aggregator.go

@@ -64,6 +64,8 @@ func createAggregatorConfig(
 	// make a shallow copy to let us twiddle a few things
 	// most of the config actually remains the same.  We only need to mess with a couple items related to the particulars of the aggregator
 	genericConfig := kubeAPIServerConfig
+	genericConfig.PostStartHooks = map[string]genericapiserver.PostStartHookConfigEntry{}
+	genericConfig.RESTOptionsGetter = nil
 
 	// override genericConfig.AdmissionControl with kube-aggregator's scheme,
 	// because aggregator apiserver should use its own scheme to convert its own resources.

cmd/kube-apiserver/app/apiextensions.go

@@ -48,6 +48,8 @@ func createAPIExtensionsConfig(
 	// make a shallow copy to let us twiddle a few things
 	// most of the config actually remains the same.  We only need to mess with a couple items related to the particulars of the apiextensions
 	genericConfig := kubeAPIServerConfig
+	genericConfig.PostStartHooks = map[string]genericapiserver.PostStartHookConfigEntry{}
+	genericConfig.RESTOptionsGetter = nil
 
 	// override genericConfig.AdmissionControl with apiextensions' scheme,
 	// because apiextentions apiserver should use its own scheme to convert resources.

cmd/kube-apiserver/app/server.go

@@ -168,7 +168,7 @@ func CreateServerChain(completedOptions completedServerRunOptions, stopCh <-chan
 		return nil, err
 	}
 
-	kubeAPIServerConfig, insecureServingInfo, serviceResolver, pluginInitializer, admissionPostStartHook, err := CreateKubeAPIServerConfig(completedOptions, nodeTunneler, proxyTransport)
+	kubeAPIServerConfig, insecureServingInfo, serviceResolver, pluginInitializer, err := CreateKubeAPIServerConfig(completedOptions, nodeTunneler, proxyTransport)
 	if err != nil {
 		return nil, err
 	}
@@ -184,7 +184,7 @@ func CreateServerChain(completedOptions completedServerRunOptions, stopCh <-chan
 		return nil, err
 	}
 
-	kubeAPIServer, err := CreateKubeAPIServer(kubeAPIServerConfig, apiExtensionsServer.GenericAPIServer, admissionPostStartHook)
+	kubeAPIServer, err := CreateKubeAPIServer(kubeAPIServerConfig, apiExtensionsServer.GenericAPIServer)
 	if err != nil {
 		return nil, err
 	}
@@ -211,14 +211,12 @@ func CreateServerChain(completedOptions completedServerRunOptions, stopCh <-chan
 }
 
 // CreateKubeAPIServer creates and wires a workable kube-apiserver
-func CreateKubeAPIServer(kubeAPIServerConfig *master.Config, delegateAPIServer genericapiserver.DelegationTarget, admissionPostStartHook genericapiserver.PostStartHookFunc) (*master.Master, error) {
+func CreateKubeAPIServer(kubeAPIServerConfig *master.Config, delegateAPIServer genericapiserver.DelegationTarget) (*master.Master, error) {
 	kubeAPIServer, err := kubeAPIServerConfig.Complete().New(delegateAPIServer)
 	if err != nil {
 		return nil, err
 	}
 
-	kubeAPIServer.GenericAPIServer.AddPostStartHookOrDie("start-kube-apiserver-admission-initializer", admissionPostStartHook)
-
 	return kubeAPIServer, nil
 }
 
@@ -273,25 +271,20 @@ func CreateKubeAPIServerConfig(
 	nodeTunneler tunneler.Tunneler,
 	proxyTransport *http.Transport,
 ) (
-	config *master.Config,
-	insecureServingInfo *genericapiserver.DeprecatedInsecureServingInfo,
-	serviceResolver aggregatorapiserver.ServiceResolver,
-	pluginInitializers []admission.PluginInitializer,
-	admissionPostStartHook genericapiserver.PostStartHookFunc,
-	lastErr error,
+	*master.Config,
+	*genericapiserver.DeprecatedInsecureServingInfo,
+	aggregatorapiserver.ServiceResolver,
+	[]admission.PluginInitializer,
+	error,
 ) {
-	var genericConfig *genericapiserver.Config
-	var storageFactory *serverstorage.DefaultStorageFactory
-	var versionedInformers clientgoinformers.SharedInformerFactory
-	genericConfig, versionedInformers, insecureServingInfo, serviceResolver, pluginInitializers, admissionPostStartHook, storageFactory, lastErr = buildGenericConfig(s.ServerRunOptions, proxyTransport)
-	if lastErr != nil {
-		return
+	genericConfig, versionedInformers, insecureServingInfo, serviceResolver, pluginInitializers, admissionPostStartHook, storageFactory, err := buildGenericConfig(s.ServerRunOptions, proxyTransport)
+	if err != nil {
+		return nil, nil, nil, nil, err
 	}
 
 	if _, port, err := net.SplitHostPort(s.Etcd.StorageConfig.Transport.ServerList[0]); err == nil && port != "0" && len(port) != 0 {
 		if err := utilwait.PollImmediate(etcdRetryInterval, etcdRetryLimit*etcdRetryInterval, preflight.EtcdConnection{ServerList: s.Etcd.StorageConfig.Transport.ServerList}.CheckEtcdServers); err != nil {
-			lastErr = fmt.Errorf("error waiting for etcd connection: %v", err)
-			return
+			return nil, nil, nil, nil, fmt.Errorf("error waiting for etcd connection: %v", err)
 		}
 	}
 
@@ -306,31 +299,31 @@ func CreateKubeAPIServerConfig(
 		PerConnectionBandwidthLimitBytesPerSec: s.MaxConnectionBytesPerSec,
 	})
 
-	serviceIPRange, apiServerServiceIP, lastErr := master.ServiceIPRange(s.PrimaryServiceClusterIPRange)
-	if lastErr != nil {
-		return
+	serviceIPRange, apiServerServiceIP, err := master.ServiceIPRange(s.PrimaryServiceClusterIPRange)
+	if err != nil {
+		return nil, nil, nil, nil, err
 	}
 
 	// defaults to empty range and ip
 	var secondaryServiceIPRange net.IPNet
 	// process secondary range only if provided by user
 	if s.SecondaryServiceClusterIPRange.IP != nil {
-		secondaryServiceIPRange, _, lastErr = master.ServiceIPRange(s.SecondaryServiceClusterIPRange)
-		if lastErr != nil {
-			return
+		secondaryServiceIPRange, _, err = master.ServiceIPRange(s.SecondaryServiceClusterIPRange)
+		if err != nil {
+			return nil, nil, nil, nil, err
 		}
 	}
 
-	clientCA, lastErr := readCAorNil(s.Authentication.ClientCert.ClientCA)
-	if lastErr != nil {
-		return
+	clientCA, err := readCAorNil(s.Authentication.ClientCert.ClientCA)
+	if err != nil {
+		return nil, nil, nil, nil, err
 	}
-	requestHeaderProxyCA, lastErr := readCAorNil(s.Authentication.RequestHeader.ClientCAFile)
-	if lastErr != nil {
-		return
+	requestHeaderProxyCA, err := readCAorNil(s.Authentication.RequestHeader.ClientCAFile)
+	if err != nil {
+		return nil, nil, nil, nil, err
 	}
 
-	config = &master.Config{
+	config := &master.Config{
 		GenericConfig: genericConfig,
 		ExtraConfig: master.ExtraConfig{
 			ClientCARegistrationHook: master.ClientCARegistrationHook{
@@ -369,6 +362,9 @@ func CreateKubeAPIServerConfig(
 			VersionedInformers: versionedInformers,
 		},
 	}
+	if err := config.GenericConfig.AddPostStartHook("start-kube-apiserver-admission-initializer", admissionPostStartHook); err != nil {
+		return nil, nil, nil, nil, err
+	}
 
 	if nodeTunneler != nil {
 		// Use the nodeTunneler's dialer to connect to the kubelet
@@ -379,7 +375,7 @@ func CreateKubeAPIServerConfig(
 		config.ExtraConfig.KubeletClientConfig.Lookup = config.GenericConfig.EgressSelector.Lookup
 	}
 
-	return
+	return config, insecureServingInfo, serviceResolver, pluginInitializers, nil
 }
 
 // BuildGenericConfig takes the master server options and produces the genericapiserver.Config associated with it

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

@@ -23,6 +23,7 @@ import (
 	"net"
 	"net/http"
 	goruntime "runtime"
+	"runtime/debug"
 	"sort"
 	"strconv"
 	"strings"
@@ -116,6 +117,8 @@ type Config struct {
 	EnableMetrics             bool
 
 	DisabledPostStartHooks sets.String
+	// done values in this values for this map are ignored.
+	PostStartHooks map[string]PostStartHookConfigEntry
 
 	// Version will enable the /version endpoint if non-nil
 	Version *version.Info
@@ -282,6 +285,7 @@ func NewConfig(codecs serializer.CodecFactory) *Config {
 		HandlerChainWaitGroup:       new(utilwaitgroup.SafeWaitGroup),
 		LegacyAPIGroupPrefixes:      sets.NewString(DefaultLegacyAPIPrefix),
 		DisabledPostStartHooks:      sets.NewString(),
+		PostStartHooks:              map[string]PostStartHookConfigEntry{},
 		HealthzChecks:               append([]healthz.HealthChecker{}, defaultHealthChecks...),
 		ReadyzChecks:                append([]healthz.HealthChecker{}, defaultHealthChecks...),
 		LivezChecks:                 append([]healthz.HealthChecker{}, defaultHealthChecks...),
@@ -391,6 +395,36 @@ func (c *Config) AddHealthChecks(healthChecks ...healthz.HealthChecker) {
 	}
 }
 
+// AddPostStartHook allows you to add a PostStartHook that will later be added to the server itself in a New call.
+// Name conflicts will cause an error.
+func (c *Config) AddPostStartHook(name string, hook PostStartHookFunc) error {
+	if len(name) == 0 {
+		return fmt.Errorf("missing name")
+	}
+	if hook == nil {
+		return fmt.Errorf("hook func may not be nil: %q", name)
+	}
+	if c.DisabledPostStartHooks.Has(name) {
+		klog.V(1).Infof("skipping %q because it was explicitly disabled", name)
+		return nil
+	}
+
+	if postStartHook, exists := c.PostStartHooks[name]; exists {
+		// this is programmer error, but it can be hard to debug
+		return fmt.Errorf("unable to add %q because it was already registered by: %s", name, postStartHook.originatingStack)
+	}
+	c.PostStartHooks[name] = PostStartHookConfigEntry{hook: hook, originatingStack: string(debug.Stack())}
+
+	return nil
+}
+
+// AddPostStartHookOrDie allows you to add a PostStartHook, but dies on failure.
+func (c *Config) AddPostStartHookOrDie(name string, hook PostStartHookFunc) {
+	if err := c.AddPostStartHook(name, hook); err != nil {
+		klog.Fatalf("Error registering PostStartHook %q: %v", name, err)
+	}
+}
+
 // Complete fills in any fields not set that are required to have valid data and can be derived
 // from other fields. If you're going to `ApplyOptions`, do that first. It's mutating the receiver.
 func (c *Config) Complete(informers informers.SharedInformerFactory) CompletedConfig {
@@ -552,6 +586,7 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 		}
 	}
 
+	// first add poststarthooks from delegated targets
 	for k, v := range delegationTarget.PostStartHooks() {
 		s.postStartHooks[k] = v
 	}
@@ -560,6 +595,13 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 		s.preShutdownHooks[k] = v
 	}
 
+	// add poststarthooks that were preconfigured.  Using the add method will give us an error if the same name has already been registered.
+	for name, preconfiguredPostStartHook := range c.PostStartHooks {
+		if err := s.AddPostStartHook(name, preconfiguredPostStartHook.hook); err != nil {
+			return nil, err
+		}
+	}
+
 	genericApiServerHookName := "generic-apiserver-start-informers"
 	if c.SharedInformerFactory != nil && !s.isPostStartHookRegistered(genericApiServerHookName) {
 		err := s.AddPostStartHook(genericApiServerHookName, func(context PostStartHookContext) error {
@@ -613,7 +655,6 @@ func DefaultBuildHandlerChain(apiHandler http.Handler, c *Config) http.Handler {
 	handler = genericfilters.WithTimeoutForNonLongRunningRequests(handler, c.LongRunningFunc, c.RequestTimeout)
 	handler = genericfilters.WithWaitGroup(handler, c.LongRunningFunc, c.HandlerChainWaitGroup)
 	handler = genericapifilters.WithRequestInfo(handler, c.RequestInfoResolver)
-	handler = genericapifilters.WithCacheControl(handler)
 	handler = genericfilters.WithPanicRecovery(handler)
 	return handler
 }

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

@@ -66,6 +66,13 @@ type postStartHookEntry struct {
 	done chan struct{}
 }
 
+type PostStartHookConfigEntry struct {
+	hook PostStartHookFunc
+	// originatingStack holds the stack that registered postStartHooks. This allows us to show a more helpful message
+	// for duplicate registration.
+	originatingStack string
+}
+
 type preShutdownHookEntry struct {
 	hook PreShutdownHookFunc
 }
@@ -76,9 +83,10 @@ func (s *GenericAPIServer) AddPostStartHook(name string, hook PostStartHookFunc)
 		return fmt.Errorf("missing name")
 	}
 	if hook == nil {
-		return nil
+		return fmt.Errorf("hook func may not be nil: %q", name)
 	}
 	if s.disabledPostStartHooks.Has(name) {
+		klog.V(1).Infof("skipping %q because it was explicitly disabled", name)
 		return nil
 	}
 

test/integration/examples/apiserver_test.go

@@ -118,7 +118,7 @@ func TestAggregatedAPIServer(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		kubeAPIServerConfig, _, _, _, admissionPostStartHook, err := app.CreateKubeAPIServerConfig(completedOptions, tunneler, proxyTransport)
+		kubeAPIServerConfig, _, _, _, err := app.CreateKubeAPIServerConfig(completedOptions, tunneler, proxyTransport)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -129,7 +129,7 @@ func TestAggregatedAPIServer(t *testing.T) {
 		kubeAPIServerClientConfig.ServerName = ""
 		kubeClientConfigValue.Store(kubeAPIServerClientConfig)
 
-		kubeAPIServer, err := app.CreateKubeAPIServer(kubeAPIServerConfig, genericapiserver.NewEmptyDelegate(), admissionPostStartHook)
+		kubeAPIServer, err := app.CreateKubeAPIServer(kubeAPIServerConfig, genericapiserver.NewEmptyDelegate())
 		if err != nil {
 			t.Fatal(err)
 		}

test/integration/framework/test_server.go

@@ -113,7 +113,7 @@ func StartTestServer(t *testing.T, stopCh <-chan struct{}, setup TestServerSetup
 	if err != nil {
 		t.Fatal(err)
 	}
-	kubeAPIServerConfig, _, _, _, admissionPostStartHook, err := app.CreateKubeAPIServerConfig(completedOptions, tunneler, proxyTransport)
+	kubeAPIServerConfig, _, _, _, err := app.CreateKubeAPIServerConfig(completedOptions, tunneler, proxyTransport)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -121,7 +121,7 @@ func StartTestServer(t *testing.T, stopCh <-chan struct{}, setup TestServerSetup
 	if setup.ModifyServerConfig != nil {
 		setup.ModifyServerConfig(kubeAPIServerConfig)
 	}
-	kubeAPIServer, err := app.CreateKubeAPIServer(kubeAPIServerConfig, genericapiserver.NewEmptyDelegate(), admissionPostStartHook)
+	kubeAPIServer, err := app.CreateKubeAPIServer(kubeAPIServerConfig, genericapiserver.NewEmptyDelegate())
 	if err != nil {
 		t.Fatal(err)
 	}