Merge pull request #8350 from Arpit529Srivastava/kubelet-cmd-flag

feat: add flag to disable insecure kubelet metrics port

Documentation/platform/operator.md

@@ -75,6 +75,8 @@ Arguments:
     	Create Endpoints objects for kubelet targets. (default true)
   -kubelet-endpointslice
     	Create EndpointSlice objects for kubelet targets.
+  -kubelet-http-metrics
+    	Include HTTP metrics port (10255) in kubelet service. Set to false if your cluster has disabled the insecure kubelet read-only port (e.g., GKE 1.32+). (default true)
   -kubelet-node-address-priority value
     	Node address priority used by kubelet. Either 'internal' or 'external'. Default: 'internal'.
   -kubelet-selector value

cmd/operator/main.go

@@ -128,6 +128,7 @@ var (
 	kubeletEndpoints     bool
 	kubeletEndpointSlice bool
 	kubeletSyncPeriod    time.Duration
+	kubeletHTTPMetrics   bool
 
 	featureGates = k8sflag.NewMapStringBool(ptr.To(map[string]bool{}))
 )
@@ -150,6 +151,7 @@ func parseFlags(fs *flag.FlagSet) {
 	fs.BoolVar(&kubeletEndpointSlice, "kubelet-endpointslice", false, "Create EndpointSlice objects for kubelet targets.")
 	fs.BoolVar(&kubeletEndpoints, "kubelet-endpoints", true, "Create Endpoints objects for kubelet targets.")
 	fs.DurationVar(&kubeletSyncPeriod, "kubelet-sync-period", 3*time.Minute, "How often the operator reconciles the kubelet Endpoints and EndpointSlice objects (e.g., 10s, 2m, 1h30m).")
+	fs.BoolVar(&kubeletHTTPMetrics, "kubelet-http-metrics", true, "Include HTTP metrics port (10255) in kubelet service. Set to false if your cluster has disabled the insecure kubelet read-only port (e.g., GKE 1.32+).")
 
 	// The Prometheus config reloader image is released along with the
 	// Prometheus Operator image, tagged with the same semver version. Default to
@@ -661,6 +663,7 @@ func start() int {
 		opts := []kubelet.ControllerOption{
 			kubelet.WithNodeAddressPriority(nodeAddressPriority.String()),
 			kubelet.WithSyncPeriod(kubeletSyncPeriod),
+			kubelet.WithHTTPMetrics(kubeletHTTPMetrics),
 		}
 
 		kubeletService := strings.Split(kubeletObject, "/")

pkg/kubelet/controller.go

@@ -74,6 +74,11 @@ type Controller struct {
 	manageEndpointSlice bool
 	manageEndpoints     bool
 	syncPeriod          time.Duration
+
+	// httpMetricsEnabled controls whether to include the insecure HTTP metrics
+	// port (10255) in the kubelet Service. Set to false when the cluster has
+	// disabled the insecure kubelet read-only port (e.g., GKE 1.32+).
+	httpMetricsEnabled bool
 }
 
 type ControllerOption func(*Controller)
@@ -108,6 +113,16 @@ func WithSyncPeriod(d time.Duration) ControllerOption {
 	}
 }
 
+// WithHTTPMetrics controls whether to include the insecure HTTP metrics port
+// (10255) in the kubelet Service. When disabled, only the secure HTTPS port
+// (10250) and cAdvisor port (4194) are included. This is useful when the
+// cluster has disabled the insecure kubelet read-only port (e.g., GKE 1.32+).
+func WithHTTPMetrics(enabled bool) ControllerOption {
+	return func(c *Controller) {
+		c.httpMetricsEnabled = enabled
+	}
+}
+
 func New(
 	logger *slog.Logger,
 	kclient kubernetes.Interface,
@@ -433,20 +448,7 @@ func (c *Controller) syncEndpoints(ctx context.Context, addresses []nodeAddress)
 		Subsets: []v1.EndpointSubset{
 			{
 				Addresses: make([]v1.EndpointAddress, len(addresses)),
-				Ports: []v1.EndpointPort{
-					{
-						Name: httpsPortName,
-						Port: httpsPort,
-					},
-					{
-						Name: httpPortName,
-						Port: httpPort,
-					},
-					{
-						Name: cAdvisorPortName,
-						Port: cAdvisorPort,
-					},
-				},
+				Ports:     c.endpointPorts(),
 			},
 		},
 	}
@@ -486,20 +488,7 @@ func (c *Controller) syncService(ctx context.Context) (*v1.Service, error) {
 		Spec: v1.ServiceSpec{
 			Type:      v1.ServiceTypeClusterIP,
 			ClusterIP: v1.ClusterIPNone,
-			Ports: []v1.ServicePort{
-				{
-					Name: httpsPortName,
-					Port: httpsPort,
-				},
-				{
-					Name: httpPortName,
-					Port: httpPort,
-				},
-				{
-					Name: cAdvisorPortName,
-					Port: cAdvisorPort,
-				},
-			},
+			Ports:     c.servicePorts(),
 		},
 	}
 
@@ -626,20 +615,7 @@ func (c *Controller) syncEndpointSlice(ctx context.Context, svc *v1.Service, add
 					},
 					},
 				},
-				Ports: []discoveryv1.EndpointPort{
-					{
-						Name: ptr.To(httpsPortName),
-						Port: ptr.To(httpsPort),
-					},
-					{
-						Name: ptr.To(httpPortName),
-						Port: ptr.To(httpPort),
-					},
-					{
-						Name: ptr.To(cAdvisorPortName),
-						Port: ptr.To(cAdvisorPort),
-					},
-				},
+				Ports: c.endpointSlicePorts(),
 			}
 
 			if a.ipv4 {
@@ -688,3 +664,75 @@ func (c *Controller) syncEndpointSlice(ctx context.Context, svc *v1.Service, add
 func (c *Controller) fullCapacity(eps []discoveryv1.Endpoint) bool {
 	return len(eps) >= c.maxEndpointsPerSlice
 }
+
+// servicePorts returns the list of ServicePort for the kubelet Service.
+// If httpMetricsEnabled is false, the insecure HTTP port (10255) is excluded.
+func (c *Controller) servicePorts() []v1.ServicePort {
+	ports := []v1.ServicePort{
+		{
+			Name: httpsPortName,
+			Port: httpsPort,
+		},
+		{
+			Name: cAdvisorPortName,
+			Port: cAdvisorPort,
+		},
+	}
+
+	if c.httpMetricsEnabled {
+		ports = append(ports, v1.ServicePort{
+			Name: httpPortName,
+			Port: httpPort,
+		})
+	}
+
+	return ports
+}
+
+// endpointPorts returns the list of EndpointPort for the kubelet Endpoints.
+// If httpMetricsEnabled is false, the insecure HTTP port (10255) is excluded.
+func (c *Controller) endpointPorts() []v1.EndpointPort {
+	ports := []v1.EndpointPort{
+		{
+			Name: httpsPortName,
+			Port: httpsPort,
+		},
+		{
+			Name: cAdvisorPortName,
+			Port: cAdvisorPort,
+		},
+	}
+
+	if c.httpMetricsEnabled {
+		ports = append(ports, v1.EndpointPort{
+			Name: httpPortName,
+			Port: httpPort,
+		})
+	}
+
+	return ports
+}
+
+// endpointSlicePorts returns the list of EndpointPort for the kubelet EndpointSlice.
+// If httpMetricsEnabled is false, the insecure HTTP port (10255) is excluded.
+func (c *Controller) endpointSlicePorts() []discoveryv1.EndpointPort {
+	ports := []discoveryv1.EndpointPort{
+		{
+			Name: ptr.To(httpsPortName),
+			Port: ptr.To(httpsPort),
+		},
+		{
+			Name: ptr.To(cAdvisorPortName),
+			Port: ptr.To(cAdvisorPort),
+		},
+	}
+
+	if c.httpMetricsEnabled {
+		ports = append(ports, discoveryv1.EndpointPort{
+			Name: ptr.To(httpPortName),
+			Port: ptr.To(httpPort),
+		})
+	}
+
+	return ports
+}

pkg/kubelet/controller_test.go

@@ -584,3 +584,73 @@ func newLogger() *slog.Logger {
 
 	return l
 }
+
+func TestHTTPMetricsPorts(t *testing.T) {
+	for _, tc := range []struct {
+		name                  string
+		httpMetricsEnabled    bool
+		expectedServicePorts  int
+		expectedEndpointPorts int
+		expectHTTPMetricsPort bool
+	}{
+		{
+			name:                  "HTTP metrics enabled (default)",
+			httpMetricsEnabled:    true,
+			expectedServicePorts:  3, // https-metrics, http-metrics, cadvisor
+			expectedEndpointPorts: 3,
+			expectHTTPMetricsPort: true,
+		},
+		{
+			name:                  "HTTP metrics disabled",
+			httpMetricsEnabled:    false,
+			expectedServicePorts:  2, // https-metrics, cadvisor (no http-metrics)
+			expectedEndpointPorts: 2,
+			expectHTTPMetricsPort: false,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			c := &Controller{
+				httpMetricsEnabled: tc.httpMetricsEnabled,
+			}
+
+			// Test servicePorts
+			svcPorts := c.servicePorts()
+			require.Len(t, svcPorts, tc.expectedServicePorts, "unexpected number of service ports")
+
+			hasHTTPPort := false
+			for _, p := range svcPorts {
+				if p.Name == httpPortName && p.Port == httpPort {
+					hasHTTPPort = true
+					break
+				}
+			}
+			require.Equal(t, tc.expectHTTPMetricsPort, hasHTTPPort, "http-metrics port presence mismatch in service ports")
+
+			// Test endpointPorts
+			epPorts := c.endpointPorts()
+			require.Len(t, epPorts, tc.expectedEndpointPorts, "unexpected number of endpoint ports")
+
+			hasHTTPPort = false
+			for _, p := range epPorts {
+				if p.Name == httpPortName && p.Port == httpPort {
+					hasHTTPPort = true
+					break
+				}
+			}
+			require.Equal(t, tc.expectHTTPMetricsPort, hasHTTPPort, "http-metrics port presence mismatch in endpoint ports")
+
+			// Test endpointSlicePorts
+			epsPorts := c.endpointSlicePorts()
+			require.Len(t, epsPorts, tc.expectedEndpointPorts, "unexpected number of endpointslice ports")
+
+			hasHTTPPort = false
+			for _, p := range epsPorts {
+				if p.Name != nil && *p.Name == httpPortName && p.Port != nil && *p.Port == httpPort {
+					hasHTTPPort = true
+					break
+				}
+			}
+			require.Equal(t, tc.expectHTTPMetricsPort, hasHTTPPort, "http-metrics port presence mismatch in endpointslice ports")
+		})
+	}
+}