also ping the webhook server after start

pkg/webhook/server.go

@@ -28,6 +28,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"sync"
+	"time"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	kscheme "k8s.io/client-go/kubernetes/scheme"
@@ -294,9 +295,17 @@ func (s *Server) StartedChecker() healthz.Checker {
 	return func(req *http.Request) error {
 		s.mu.Lock()
 		defer s.mu.Unlock()
+
 		if !s.started {
 			return fmt.Errorf("webhook server has not been started yet")
 		}
+
+		conn, err := net.DialTimeout("tcp", net.JoinHostPort(s.Host, strconv.Itoa(s.Port)), 10*time.Second)
+		if err != nil {
+			return fmt.Errorf("webhook server is not reachable: %v", err)
+		}
+		conn.Close()
+
 		return nil
 	}
 }

pkg/webhook/server_test.go

@@ -128,6 +128,8 @@ var _ = Describe("Webhook Server", func() {
 		It("should serve a webhook on the requested path", func() {
 			server.Register("/somepath", &testHandler{})
 
+			Expect(server.StartedChecker()(nil)).ToNot(Succeed())
+
 			doneCh := startServer()
 
 			Eventually(func() ([]byte, error) {