Merge pull request #78458 from logicalhan/readiness

Add readyz endpoint to apiserver, modify poststarthooks health checking behavior

cmd/kube-apiserver/app/testing/BUILD

@@ -17,6 +17,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/registry/generic/registry:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/server/healthz:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/storagebackend:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",
         "//staging/src/k8s.io/client-go/rest:go_default_library",

cmd/kube-apiserver/app/testing/testserver.go

@@ -25,12 +25,13 @@ import (
 	"runtime"
 	"time"
 
-	pflag "github.com/spf13/pflag"
+	"github.com/spf13/pflag"
 
 	"k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/registry/generic/registry"
+	"k8s.io/apiserver/pkg/server/healthz"
 	"k8s.io/apiserver/pkg/storage/storagebackend"
 	"k8s.io/client-go/kubernetes"
 	restclient "k8s.io/client-go/rest"
@@ -45,6 +46,8 @@ type TearDownFunc func()
 type TestServerInstanceOptions struct {
 	// DisableStorageCleanup Disable the automatic storage cleanup
 	DisableStorageCleanup bool
+	// Injected health
+	InjectedHealthzChecker healthz.HealthzChecker
 }
 
 // TestServer return values supplied by kube-test-ApiServer
@@ -144,6 +147,12 @@ func StartTestServer(t Logger, instanceOptions *TestServerInstanceOptions, custo
 	t.Logf("runtime-config=%v", completedOptions.APIEnablement.RuntimeConfig)
 	t.Logf("Starting kube-apiserver on port %d...", s.SecureServing.BindPort)
 	server, err := app.CreateServerChain(completedOptions, stopCh)
+
+	if instanceOptions.InjectedHealthzChecker != nil {
+		t.Logf("Adding health check with delay %v %v", s.GenericServerRunOptions.MaxStartupSequenceDuration, instanceOptions.InjectedHealthzChecker.Name())
+		server.AddDelayedHealthzChecks(s.GenericServerRunOptions.MaxStartupSequenceDuration, instanceOptions.InjectedHealthzChecker)
+	}
+
 	if err != nil {
 		return result, fmt.Errorf("failed to create server chain: %v", err)
 	}

plugin/pkg/auth/authorizer/rbac/bootstrappolicy/policy.go

@@ -198,7 +198,7 @@ func ClusterRoles() []rbacv1.ClusterRole {
 			ObjectMeta: metav1.ObjectMeta{Name: "system:discovery"},
 			Rules: []rbacv1.PolicyRule{
 				rbacv1helpers.NewRule("get").URLs(
-					"/healthz", "/version", "/version/",
+					"/readyz", "/healthz", "/version", "/version/",
 					"/openapi", "/openapi/*",
 					"/api", "/api/*",
 					"/apis", "/apis/*",
@@ -218,7 +218,7 @@ func ClusterRoles() []rbacv1.ClusterRole {
 			ObjectMeta: metav1.ObjectMeta{Name: "system:public-info-viewer"},
 			Rules: []rbacv1.PolicyRule{
 				rbacv1helpers.NewRule("get").URLs(
-					"/healthz", "/version", "/version/",
+					"/readyz", "/healthz", "/version", "/version/",
 				).RuleOrDie(),
 			},
 		},

plugin/pkg/auth/authorizer/rbac/bootstrappolicy/testdata/cluster-roles.yaml

@@ -535,6 +535,7 @@ items:
     - /healthz
     - /openapi
     - /openapi/*
+    - /readyz
     - /version
     - /version/
     verbs:
@@ -1156,6 +1157,7 @@ items:
   rules:
   - nonResourceURLs:
     - /healthz
+    - /readyz
     - /version
     - /version/
     verbs:

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

@@ -12,6 +12,7 @@ go_test(
         "config_selfclient_test.go",
         "config_test.go",
         "genericapiserver_test.go",
+        "healthz_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
@@ -19,6 +20,7 @@ go_test(
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/serializer:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/clock:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/version:go_default_library",
@@ -66,6 +68,7 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/runtime/serializer:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/clock:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/errors:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",

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

@@ -32,11 +32,11 @@ import (
 	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/go-openapi/spec"
 	"github.com/pborman/uuid"
-	"k8s.io/klog"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/util/clock"
 	"k8s.io/apimachinery/pkg/util/sets"
 	utilwaitgroup "k8s.io/apimachinery/pkg/util/waitgroup"
 	"k8s.io/apimachinery/pkg/version"
@@ -65,6 +65,7 @@ import (
 	restclient "k8s.io/client-go/rest"
 	certutil "k8s.io/client-go/util/cert"
 	"k8s.io/component-base/logs"
+	"k8s.io/klog"
 	openapicommon "k8s.io/kube-openapi/pkg/common"
 
 	// install apis
@@ -135,6 +136,8 @@ type Config struct {
 	DiscoveryAddresses discovery.Addresses
 	// The default set of healthz checks. There might be more added via AddHealthzChecks dynamically.
 	HealthzChecks []healthz.HealthzChecker
+	// The default set of readyz-only checks. There might be more added via AddReadyzChecks dynamically.
+	ReadyzChecks []healthz.HealthzChecker
 	// LegacyAPIGroupPrefixes is used to set up URL parsing for authorization and for validating requests
 	// to InstallLegacyAPIGroup. New API servers don't generally have legacy groups at all.
 	LegacyAPIGroupPrefixes sets.String
@@ -156,6 +159,12 @@ type Config struct {
 	// If specified, long running requests such as watch will be allocated a random timeout between this value, and
 	// twice this value.  Note that it is up to the request handlers to ignore or honor this timeout. In seconds.
 	MinRequestTimeout int
+
+	// This represents the maximum amount of time it should take for apiserver to complete its startup
+	// sequence and become healthy. From apiserver's start time to when this amount of time has
+	// elapsed, /healthz will assume that unfinished post-start hooks will complete successfully and
+	// therefore return true.
+	MaxStartupSequenceDuration time.Duration
 	// The limit on the total size increase all "copy" operations in a json
 	// patch may cause.
 	// This affects all places that applies json patch in the binary.
@@ -256,13 +265,15 @@ type AuthorizationInfo struct {
 
 // NewConfig returns a Config struct with the default values
 func NewConfig(codecs serializer.CodecFactory) *Config {
+	defaultHealthChecks := []healthz.HealthzChecker{healthz.PingHealthz, healthz.LogHealthz}
 	return &Config{
 		Serializer:                  codecs,
 		BuildHandlerChainFunc:       DefaultBuildHandlerChain,
 		HandlerChainWaitGroup:       new(utilwaitgroup.SafeWaitGroup),
 		LegacyAPIGroupPrefixes:      sets.NewString(DefaultLegacyAPIPrefix),
 		DisabledPostStartHooks:      sets.NewString(),
-		HealthzChecks:               []healthz.HealthzChecker{healthz.PingHealthz, healthz.LogHealthz},
+		HealthzChecks:               append([]healthz.HealthzChecker{}, defaultHealthChecks...),
+		ReadyzChecks:                append([]healthz.HealthzChecker{}, defaultHealthChecks...),
 		EnableIndex:                 true,
 		EnableDiscovery:             true,
 		EnableProfiling:             true,
@@ -271,6 +282,7 @@ func NewConfig(codecs serializer.CodecFactory) *Config {
 		MaxMutatingRequestsInFlight: 200,
 		RequestTimeout:              time.Duration(60) * time.Second,
 		MinRequestTimeout:           1800,
+		MaxStartupSequenceDuration:  time.Duration(0),
 		// 10MB is the recommended maximum client request size in bytes
 		// the etcd server should accept. See
 		// https://github.com/etcd-io/etcd/blob/release-3.3/etcdserver/server.go#L90.
@@ -479,7 +491,6 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 
 		minRequestTimeout: time.Duration(c.MinRequestTimeout) * time.Second,
 		ShutdownTimeout:   c.RequestTimeout,
-
 		SecureServingInfo: c.SecureServing,
 		ExternalAddress:   c.ExternalAddress,
 
@@ -493,12 +504,16 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 		preShutdownHooks:       map[string]preShutdownHookEntry{},
 		disabledPostStartHooks: c.DisabledPostStartHooks,
 
-		healthzChecks: c.HealthzChecks,
+		healthzChecks:              c.HealthzChecks,
+		readyzChecks:               c.ReadyzChecks,
+		readinessStopCh:            make(chan struct{}),
+		maxStartupSequenceDuration: c.MaxStartupSequenceDuration,
 
 		DiscoveryGroupManager: discovery.NewRootAPIsHandler(c.DiscoveryAddresses, c.Serializer),
 
 		enableAPIResponseCompression: c.EnableAPIResponseCompression,
 		maxRequestBodyBytes:          c.MaxRequestBodyBytes,
+		healthzClock:                 clock.RealClock{},
 	}
 
 	for {
@@ -546,6 +561,7 @@ func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*G
 		}
 
 		s.healthzChecks = append(s.healthzChecks, delegateCheck)
+		s.readyzChecks = append(s.readyzChecks, delegateCheck)
 	}
 
 	s.listedPathProvider = routes.ListedPathProviders{s.listedPathProvider, delegationTarget}

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

@@ -115,7 +115,15 @@ func TestNewWithDelegate(t *testing.T) {
     "/healthz/poststarthook/generic-apiserver-start-informers",
     "/healthz/poststarthook/wrapping-post-start-hook",
     "/healthz/wrapping-health",
-    "/metrics"
+    "/metrics",
+    "/readyz",
+    "/readyz/delegate-health",
+    "/readyz/log",
+    "/readyz/ping",
+    "/readyz/poststarthook/delegate-post-start-hook",
+    "/readyz/poststarthook/generic-apiserver-start-informers",
+    "/readyz/poststarthook/wrapping-post-start-hook",
+    "/readyz/shutdown"
   ]
 }`, t)
 	checkPath(server.URL+"/healthz", http.StatusInternalServerError, `[+]ping ok

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

@@ -26,13 +26,13 @@ import (
 
 	systemd "github.com/coreos/go-systemd/daemon"
 	"github.com/go-openapi/spec"
-	"k8s.io/klog"
 
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/util/clock"
 	"k8s.io/apimachinery/pkg/util/sets"
 	utilwaitgroup "k8s.io/apimachinery/pkg/util/waitgroup"
 	"k8s.io/apiserver/pkg/admission"
@@ -45,6 +45,7 @@ import (
 	"k8s.io/apiserver/pkg/server/routes"
 	utilopenapi "k8s.io/apiserver/pkg/util/openapi"
 	restclient "k8s.io/client-go/rest"
+	"k8s.io/klog"
 	openapibuilder "k8s.io/kube-openapi/pkg/builder"
 	openapicommon "k8s.io/kube-openapi/pkg/common"
 	"k8s.io/kube-openapi/pkg/handler"
@@ -145,9 +146,17 @@ type GenericAPIServer struct {
 	preShutdownHooksCalled bool
 
 	// healthz checks
-	healthzLock    sync.Mutex
-	healthzChecks  []healthz.HealthzChecker
-	healthzCreated bool
+	healthzLock                sync.Mutex
+	healthzChecks              []healthz.HealthzChecker
+	healthzChecksInstalled     bool
+	readyzLock                 sync.Mutex
+	readyzChecks               []healthz.HealthzChecker
+	readyzChecksInstalled      bool
+	maxStartupSequenceDuration time.Duration
+	healthzClock               clock.Clock
+	// the readiness stop channel is used to signal that the apiserver has initiated a shutdown sequence, this
+	// will cause readyz to return unhealthy.
+	readinessStopCh chan struct{}
 
 	// auditing. The backend is started after the server starts listening.
 	AuditBackend audit.Backend
@@ -259,6 +268,7 @@ func (s *GenericAPIServer) PrepareRun() preparedGenericAPIServer {
 	}
 
 	s.installHealthz()
+	s.installReadyz(s.readinessStopCh)
 
 	// Register audit backend preShutdownHook.
 	if s.AuditBackend != nil {
@@ -327,6 +337,7 @@ func (s preparedGenericAPIServer) NonBlockingRun(stopCh <-chan struct{}) error {
 	// ensure cleanup.
 	go func() {
 		<-stopCh
+		close(s.readinessStopCh)
 		close(internalStopCh)
 		if stoppedCh != nil {
 			<-stoppedCh

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

@@ -18,20 +18,30 @@ package server
 
 import (
 	"fmt"
+	"net/http"
+	"time"
 
+	"k8s.io/apimachinery/pkg/util/clock"
 	"k8s.io/apiserver/pkg/server/healthz"
 )
 
-// AddHealthzCheck allows you to add a HealthzCheck.
+// AddHealthzCheck adds HealthzCheck(s) to both healthz and readyz. All healthz checks
+// are automatically added to readyz, since we want to avoid the situation where the
+// apiserver is ready but not live.
 func (s *GenericAPIServer) AddHealthzChecks(checks ...healthz.HealthzChecker) error {
-	s.healthzLock.Lock()
-	defer s.healthzLock.Unlock()
+	return s.AddDelayedHealthzChecks(0, checks...)
+}
 
-	if s.healthzCreated {
-		return fmt.Errorf("unable to add because the healthz endpoint has already been created")
+// AddReadyzChecks allows you to add a HealthzCheck to readyz.
+func (s *GenericAPIServer) AddReadyzChecks(checks ...healthz.HealthzChecker) error {
+	s.readyzLock.Lock()
+	defer s.readyzLock.Unlock()
+
+	if s.readyzChecksInstalled {
+		return fmt.Errorf("unable to add because the readyz endpoint has already been created")
 	}
 
-	s.healthzChecks = append(s.healthzChecks, checks...)
+	s.readyzChecks = append(s.readyzChecks, checks...)
 	return nil
 }
 
@@ -39,7 +49,81 @@ func (s *GenericAPIServer) AddHealthzChecks(checks ...healthz.HealthzChecker) er
 func (s *GenericAPIServer) installHealthz() {
 	s.healthzLock.Lock()
 	defer s.healthzLock.Unlock()
-	s.healthzCreated = true
+	s.healthzChecksInstalled = true
 
 	healthz.InstallHandler(s.Handler.NonGoRestfulMux, s.healthzChecks...)
 }
+
+// installReadyz creates the readyz endpoint for this server.
+func (s *GenericAPIServer) installReadyz(stopCh <-chan struct{}) {
+	s.AddReadyzChecks(shutdownCheck{stopCh})
+	s.readyzLock.Lock()
+	defer s.readyzLock.Unlock()
+
+	s.readyzChecksInstalled = true
+
+	healthz.InstallReadyzHandler(s.Handler.NonGoRestfulMux, s.readyzChecks...)
+}
+
+// shutdownCheck fails if the embedded channel is closed. This is intended to allow for graceful shutdown sequences
+// for the apiserver.
+type shutdownCheck struct {
+	StopCh <-chan struct{}
+}
+
+func (shutdownCheck) Name() string {
+	return "shutdown"
+}
+
+func (c shutdownCheck) Check(req *http.Request) error {
+	select {
+	case <-c.StopCh:
+		return fmt.Errorf("process is shutting down")
+	default:
+	}
+	return nil
+}
+
+// AddDelayedHealthzChecks adds a health check to both healthz and readyz. The delay parameter
+// allows you to set the grace period for healthz checks, which will return healthy while
+// grace period has not yet elapsed. One may want to set a grace period in order to prevent
+// the kubelet from restarting the kube-apiserver due to long-ish boot sequences. Readyz health
+// checks have no grace period, since we want readyz to fail while boot has not completed.
+func (s *GenericAPIServer) AddDelayedHealthzChecks(delay time.Duration, checks ...healthz.HealthzChecker) error {
+	s.healthzLock.Lock()
+	defer s.healthzLock.Unlock()
+	if s.healthzChecksInstalled {
+		return fmt.Errorf("unable to add because the healthz endpoint has already been created")
+	}
+	for _, check := range checks {
+		s.healthzChecks = append(s.healthzChecks, delayedHealthCheck(check, s.healthzClock, s.maxStartupSequenceDuration))
+	}
+
+	return s.AddReadyzChecks(checks...)
+}
+
+// delayedHealthCheck wraps a health check which will not fail until the explicitly defined delay has elapsed.
+func delayedHealthCheck(check healthz.HealthzChecker, clock clock.Clock, delay time.Duration) healthz.HealthzChecker {
+	return delayedHealthzCheck{
+		check,
+		clock.Now().Add(delay),
+		clock,
+	}
+}
+
+type delayedHealthzCheck struct {
+	check      healthz.HealthzChecker
+	startCheck time.Time
+	clock      clock.Clock
+}
+
+func (c delayedHealthzCheck) Name() string {
+	return c.check.Name()
+}
+
+func (c delayedHealthzCheck) Check(req *http.Request) error {
+	if c.clock.Now().After(c.startCheck) {
+		return c.check.Check(req)
+	}
+	return nil
+}

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

@@ -93,6 +93,14 @@ func InstallHandler(mux mux, checks ...HealthzChecker) {
 	InstallPathHandler(mux, "/healthz", checks...)
 }
 
+// InstallReadyzHandler registers handlers for health checking on the path
+// "/readyz" to mux. *All handlers* for mux must be specified in
+// exactly one call to InstallHandler. Calling InstallHandler more
+// than once for the same mux will result in a panic.
+func InstallReadyzHandler(mux mux, checks ...HealthzChecker) {
+	InstallPathHandler(mux, "/readyz", checks...)
+}
+
 // InstallPathHandler registers handlers for health checking on
 // a specific path to mux. *All handlers* for the path must be
 // specified in exactly one call to InstallPathHandler. Calling

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

@@ -0,0 +1,77 @@
+/*
+Copyright 2019 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 server
+
+import (
+	"testing"
+	"time"
+
+	"k8s.io/apimachinery/pkg/util/clock"
+)
+
+func TestDelayedHealthCheck(t *testing.T) {
+	t.Run("test that liveness check returns true until the delay has elapsed", func(t *testing.T) {
+		t0 := time.Unix(0, 0)
+		c := clock.NewFakeClock(t0)
+		doneCh := make(chan struct{})
+
+		healthCheck := delayedHealthCheck(postStartHookHealthz{"test", doneCh}, c, time.Duration(10)*time.Second)
+		err := healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+		c.Step(10 * time.Second)
+		err = healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+		c.Step(1 * time.Millisecond)
+		err = healthCheck.Check(nil)
+		if err == nil || err.Error() != "not finished" {
+			t.Errorf("Got '%v', but expected error to be 'not finished'", err)
+		}
+		close(doneCh)
+		err = healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+	})
+	t.Run("test that liveness check does not toggle false even if done channel is closed early", func(t *testing.T) {
+		t0 := time.Unix(0, 0)
+		c := clock.NewFakeClock(t0)
+
+		doneCh := make(chan struct{})
+
+		healthCheck := delayedHealthCheck(postStartHookHealthz{"test", doneCh}, c, time.Duration(10)*time.Second)
+		err := healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+		close(doneCh)
+		c.Step(10 * time.Second)
+		err = healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+		c.Step(1 * time.Millisecond)
+		err = healthCheck.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+	})
+
+}

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

@@ -97,7 +97,7 @@ func (s *GenericAPIServer) AddPostStartHook(name string, hook PostStartHookFunc)
 	// done is closed when the poststarthook is finished.  This is used by the health check to be able to indicate
 	// that the poststarthook is finished
 	done := make(chan struct{})
-	if err := s.AddHealthzChecks(postStartHookHealthz{name: "poststarthook/" + name, done: done}); err != nil {
+	if err := s.AddDelayedHealthzChecks(s.maxStartupSequenceDuration, postStartHookHealthz{name: "poststarthook/" + name, done: done}); err != nil {
 		return err
 	}
 	s.postStartHooks[name] = postStartHookEntry{hook: hook, originatingStack: string(debug.Stack()), done: done}

staging/src/k8s.io/apiserver/pkg/server/options/server_run_options.go

@@ -41,6 +41,7 @@ type ServerRunOptions struct {
 	MaxRequestsInFlight         int
 	MaxMutatingRequestsInFlight int
 	RequestTimeout              time.Duration
+	MaxStartupSequenceDuration  time.Duration
 	MinRequestTimeout           int
 	// We intentionally did not add a flag for this option. Users of the
 	// apiserver library can wire it to a flag.
@@ -60,6 +61,7 @@ func NewServerRunOptions() *ServerRunOptions {
 		MaxRequestsInFlight:         defaults.MaxRequestsInFlight,
 		MaxMutatingRequestsInFlight: defaults.MaxMutatingRequestsInFlight,
 		RequestTimeout:              defaults.RequestTimeout,
+		MaxStartupSequenceDuration:  defaults.MaxStartupSequenceDuration,
 		MinRequestTimeout:           defaults.MinRequestTimeout,
 		JSONPatchMaxCopyBytes:       defaults.JSONPatchMaxCopyBytes,
 		MaxRequestBodyBytes:         defaults.MaxRequestBodyBytes,
@@ -72,6 +74,7 @@ func (s *ServerRunOptions) ApplyTo(c *server.Config) error {
 	c.ExternalAddress = s.ExternalHost
 	c.MaxRequestsInFlight = s.MaxRequestsInFlight
 	c.MaxMutatingRequestsInFlight = s.MaxMutatingRequestsInFlight
+	c.MaxStartupSequenceDuration = s.MaxStartupSequenceDuration
 	c.RequestTimeout = s.RequestTimeout
 	c.MinRequestTimeout = s.MinRequestTimeout
 	c.JSONPatchMaxCopyBytes = s.JSONPatchMaxCopyBytes
@@ -106,6 +109,10 @@ func (s *ServerRunOptions) Validate() []error {
 		errors = append(errors, fmt.Errorf("--target-ram-mb can not be negative value"))
 	}
 
+	if s.MaxStartupSequenceDuration < 0 {
+		errors = append(errors, fmt.Errorf("--maximum-startup-sequence-duration can not be a negative value"))
+	}
+
 	if s.EnableInfightQuotaHandler {
 		if !utilfeature.DefaultFeatureGate.Enabled(features.RequestManagement) {
 			errors = append(errors, fmt.Errorf("--enable-inflight-quota-handler can not be set if feature "+
@@ -185,6 +192,11 @@ func (s *ServerRunOptions) AddUniversalFlags(fs *pflag.FlagSet) {
 		"it out. This is the default request timeout for requests but may be overridden by flags such as "+
 		"--min-request-timeout for specific types of requests.")
 
+	fs.DurationVar(&s.MaxStartupSequenceDuration, "maximum-startup-sequence-duration", s.MaxStartupSequenceDuration, ""+
+		"This option represents the maximum amount of time it should take for apiserver to complete its startup sequence "+
+		"and become healthy. From apiserver's start time to when this amount of time has elapsed, /healthz will assume "+
+		"that unfinished post-start hooks will complete successfully and therefore return true.")
+
 	fs.IntVar(&s.MinRequestTimeout, "min-request-timeout", s.MinRequestTimeout, ""+
 		"An optional field indicating the minimum number of seconds a handler must keep "+
 		"a request open before timing it out. Currently only honored by the watch request "+

staging/src/k8s.io/apiserver/pkg/server/options/server_run_options_test.go

@@ -136,6 +136,22 @@ func TestServerRunOptionsValidate(t *testing.T) {
 			},
 			expectErr: "--max-resource-write-bytes can not be negative value",
 		},
+		{
+			name: "Test when MaxStartupSequenceDuration is negative value",
+			testOptions: &ServerRunOptions{
+				AdvertiseAddress:            net.ParseIP("192.168.10.10"),
+				CorsAllowedOriginList:       []string{"10.10.10.100", "10.10.10.200"},
+				MaxRequestsInFlight:         400,
+				MaxMutatingRequestsInFlight: 200,
+				RequestTimeout:              time.Duration(2) * time.Minute,
+				MinRequestTimeout:           1800,
+				JSONPatchMaxCopyBytes:       10 * 1024 * 1024,
+				MaxRequestBodyBytes:         10 * 1024 * 1024,
+				TargetRAMMB:                 65536,
+				MaxStartupSequenceDuration:  -time.Second,
+			},
+			expectErr: "--maximum-startup-sequence-duration can not be a negative value",
+		},
 		{
 			name: "Test when ServerRunOptions is valid",
 			testOptions: &ServerRunOptions{

test/integration/master/kube_apiserver_test.go

@@ -22,6 +22,7 @@ import (
 	"net/http"
 	"reflect"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -85,6 +86,48 @@ func TestRun(t *testing.T) {
 	}
 }
 
+func endpointReturnsStatusOK(client *kubernetes.Clientset, path string) bool {
+	res := client.CoreV1().RESTClient().Get().AbsPath(path).Do()
+	var status int
+	res.StatusCode(&status)
+	return status == http.StatusOK
+}
+
+func TestStartupSequenceHealthzAndReadyz(t *testing.T) {
+	hc := &delayedCheck{}
+	instanceOptions := &kubeapiservertesting.TestServerInstanceOptions{
+		InjectedHealthzChecker: hc,
+	}
+	server := kubeapiservertesting.StartTestServerOrDie(t, instanceOptions, []string{"--maximum-startup-sequence-duration", "5s"}, framework.SharedEtcd())
+	defer server.TearDownFn()
+
+	client, err := kubernetes.NewForConfig(server.ClientConfig)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if endpointReturnsStatusOK(client, "/readyz") {
+		t.Fatalf("readyz should start unready")
+	}
+	// we need to wait longer than our grace period
+	err = wait.Poll(100*time.Millisecond, wait.ForeverTestTimeout, func() (bool, error) {
+		return !endpointReturnsStatusOK(client, "/healthz"), nil
+	})
+	if err != nil {
+		t.Fatalf("healthz should have become unhealthy: %v", err)
+	}
+	hc.makeHealthy()
+	err = wait.Poll(100*time.Millisecond, wait.ForeverTestTimeout, func() (bool, error) {
+		return endpointReturnsStatusOK(client, "/healthz"), nil
+	})
+	if err != nil {
+		t.Fatalf("healthz should have become healthy again: %v", err)
+	}
+	if !endpointReturnsStatusOK(client, "/readyz") {
+		t.Fatalf("readyz should be healthy")
+	}
+}
+
 // TestOpenAPIDelegationChainPlumbing is a smoke test that checks for
 // the existence of some representative paths from the
 // apiextensions-server and the kube-aggregator server, both part of
@@ -253,3 +296,27 @@ func TestReconcilerMasterLeaseMultiMoreMasters(t *testing.T) {
 func TestReconcilerMasterLeaseMultiCombined(t *testing.T) {
 	testReconcilersMasterLease(t, 3, 3)
 }
+
+type delayedCheck struct {
+	healthLock sync.Mutex
+	isHealthy  bool
+}
+
+func (h *delayedCheck) Name() string {
+	return "delayed-check"
+}
+
+func (h *delayedCheck) Check(req *http.Request) error {
+	h.healthLock.Lock()
+	defer h.healthLock.Unlock()
+	if h.isHealthy {
+		return nil
+	}
+	return fmt.Errorf("isn't healthy")
+}
+
+func (h *delayedCheck) makeHealthy() {
+	h.healthLock.Lock()
+	defer h.healthLock.Unlock()
+	h.isHealthy = true
+}