Fix panic on /readyz

Signed-off-by: ialidzhikov <i.alidjikov@gmail.com>

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

@@ -11,6 +11,7 @@ go_test(
     srcs = ["healthz_test.go"],
     embed = [":go_default_library"],
     deps = [
+        "//staging/src/k8s.io/api/core/v1:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/endpoints/metrics:go_default_library",
         "//staging/src/k8s.io/component-base/metrics/legacyregistry:go_default_library",
@@ -31,7 +32,6 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/endpoints/metrics:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/server/httplog:go_default_library",
-        "//staging/src/k8s.io/client-go/informers:go_default_library",
         "//vendor/k8s.io/klog/v2:go_default_library",
     ],
 )

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

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"fmt"
 	"net/http"
+	"reflect"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -29,7 +30,6 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/endpoints/metrics"
 	"k8s.io/apiserver/pkg/server/httplog"
-	"k8s.io/client-go/informers"
 	"k8s.io/klog/v2"
 )
 
@@ -82,16 +82,20 @@ func (l *log) Check(_ *http.Request) error {
 	return fmt.Errorf("logging blocked")
 }
 
+type cacheSyncWaiter interface {
+	WaitForCacheSync(stopCh <-chan struct{}) map[reflect.Type]bool
+}
+
 type informerSync struct {
-	sharedInformerFactory informers.SharedInformerFactory
+	cacheSyncWaiter cacheSyncWaiter
 }
 
 var _ HealthChecker = &informerSync{}
 
-// NewInformerSyncHealthz returns a new HealthChecker that will pass only if all informers in the given sharedInformerFactory sync.
+// NewInformerSyncHealthz returns a new HealthChecker that will pass only if all informers in the given cacheSyncWaiter sync.
-func NewInformerSyncHealthz(sharedInformerFactory informers.SharedInformerFactory) HealthChecker {
+func NewInformerSyncHealthz(cacheSyncWaiter cacheSyncWaiter) HealthChecker {
 	return &informerSync{
-		sharedInformerFactory: sharedInformerFactory,
+		cacheSyncWaiter: cacheSyncWaiter,
 	}
 }
 
@@ -104,8 +108,8 @@ func (i *informerSync) Check(_ *http.Request) error {
 	// Close stopCh to force checking if informers are synced now.
 	close(stopCh)
 
-	var informersByStarted map[bool][]string
+	informersByStarted := make(map[bool][]string)
-	for informerType, started := range i.sharedInformerFactory.WaitForCacheSync(stopCh) {
+	for informerType, started := range i.cacheSyncWaiter.WaitForCacheSync(stopCh) {
 		informersByStarted[started] = append(informersByStarted[started], informerType.String())
 	}
 

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

@@ -26,6 +26,7 @@ import (
 	"strings"
 	"testing"
 
+	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apiserver/pkg/endpoints/metrics"
 	"k8s.io/component-base/metrics/legacyregistry"
@@ -273,3 +274,43 @@ func createGetRequestWithUrl(rawUrlString string) *http.Request {
 		URL:    url,
 	}
 }
+
+func TestInformerSyncHealthChecker(t *testing.T) {
+	t.Run("test that check returns nil when all informers are started", func(t *testing.T) {
+		healthChecker := NewInformerSyncHealthz(cacheSyncWaiterStub{
+			startedByInformerType: map[reflect.Type]bool{
+				reflect.TypeOf(corev1.Pod{}): true,
+			},
+		})
+
+		err := healthChecker.Check(nil)
+		if err != nil {
+			t.Errorf("Got %v, expected no error", err)
+		}
+	})
+
+	t.Run("test that check returns err when there is not started informer", func(t *testing.T) {
+		healthChecker := NewInformerSyncHealthz(cacheSyncWaiterStub{
+			startedByInformerType: map[reflect.Type]bool{
+				reflect.TypeOf(corev1.Pod{}):     true,
+				reflect.TypeOf(corev1.Service{}): false,
+				reflect.TypeOf(corev1.Node{}):    true,
+			},
+		})
+
+		err := healthChecker.Check(nil)
+		if err == nil {
+			t.Errorf("expected error, got: %v", err)
+		}
+	})
+}
+
+type cacheSyncWaiterStub struct {
+	startedByInformerType map[reflect.Type]bool
+}
+
+// WaitForCacheSync is a stub implementation of the corresponding func
+// that simply returns the value passed during stub initialization.
+func (s cacheSyncWaiterStub) WaitForCacheSync(_ <-chan struct{}) map[reflect.Type]bool {
+	return s.startedByInformerType
+}