Avoid the redirection to /healthz/ when calling /healthz

By #1100,
subpaths of `/healthz/` can be handled.
However, this change introduced the redirection from `/healthz`
to `/healthz/` with 301 (Moved Permanently) when accessing `/healthz`
endpoint. (Accessing `/healthz/` works fine without the redirect.)

This is unnecessary overhead in the health checking.

So, this commit enable to access `/healthz` without the redirect with keeping
that subpaths of `/healthz/` are accessible.

pkg/manager/internal.go

@@ -52,8 +52,8 @@ const (
 	defaultRetryPeriod            = 2 * time.Second
 	defaultGracefulShutdownPeriod = 30 * time.Second
 
-	defaultReadinessEndpoint = "/readyz/"
-	defaultLivenessEndpoint  = "/healthz/"
+	defaultReadinessEndpoint = "/readyz"
+	defaultLivenessEndpoint  = "/healthz"
 	defaultMetricsEndpoint   = "/metrics"
 )
 
@@ -414,9 +414,13 @@ func (cm *controllerManager) serveHealthProbes(stop <-chan struct{}) {
 
 	if cm.readyzHandler != nil {
 		mux.Handle(cm.readinessEndpointName, http.StripPrefix(cm.readinessEndpointName, cm.readyzHandler))
+		// Append '/' suffix to handle subpaths
+		mux.Handle(cm.readinessEndpointName+"/", http.StripPrefix(cm.readinessEndpointName, cm.readyzHandler))
 	}
 	if cm.healthzHandler != nil {
 		mux.Handle(cm.livenessEndpointName, http.StripPrefix(cm.livenessEndpointName, cm.healthzHandler))
+		// Append '/' suffix to handle subpaths
+		mux.Handle(cm.livenessEndpointName+"/", http.StripPrefix(cm.livenessEndpointName, cm.healthzHandler))
 	}
 
 	server := http.Server{

pkg/manager/manager_test.go

@@ -970,10 +970,15 @@ var _ = Describe("manger.Manager", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(resp.StatusCode).To(Equal(http.StatusOK))
 
-			// Check readiness path without trailing slash
+			// Check readiness path without trailing slash without redirect
 			readinessEndpoint = fmt.Sprint("http://", listener.Addr().String(), strings.TrimSuffix(defaultReadinessEndpoint, "/"))
 			res = nil
-			resp, err = http.Get(readinessEndpoint)
+			httpClient := http.Client{
+				CheckRedirect: func(req *http.Request, via []*http.Request) error {
+					return http.ErrUseLastResponse // Do not follow redirect
+				},
+			}
+			resp, err = httpClient.Get(readinessEndpoint)
 			Expect(err).NotTo(HaveOccurred())
 			Expect(resp.StatusCode).To(Equal(http.StatusOK))
 
@@ -1016,10 +1021,15 @@ var _ = Describe("manger.Manager", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(resp.StatusCode).To(Equal(http.StatusOK))
 
-			// Check liveness path without trailing slash
+			// Check liveness path without trailing slash without redirect
 			livenessEndpoint = fmt.Sprint("http://", listener.Addr().String(), strings.TrimSuffix(defaultLivenessEndpoint, "/"))
 			res = nil
-			resp, err = http.Get(livenessEndpoint)
+			httpClient := http.Client{
+				CheckRedirect: func(req *http.Request, via []*http.Request) error {
+					return http.ErrUseLastResponse // Do not follow redirect
+				},
+			}
+			resp, err = httpClient.Get(livenessEndpoint)
 			Expect(err).NotTo(HaveOccurred())
 			Expect(resp.StatusCode).To(Equal(http.StatusOK))