featuregate UID in RequestHeader authenticator

pkg/controlplane/controller/clusterauthenticationtrust/cluster_authentication_trust_controller.go

@@ -35,7 +35,9 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/apiserver/pkg/authentication/request/headerrequest"
+	"k8s.io/apiserver/pkg/features"
 	"k8s.io/apiserver/pkg/server/dynamiccertificates"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	corev1informers "k8s.io/client-go/informers/core/v1"
 	"k8s.io/client-go/kubernetes"
 	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
@@ -262,10 +264,13 @@ func getConfigMapDataFor(authenticationInfo ClusterAuthenticationInfo) (map[stri
 		if err != nil {
 			return nil, err
 		}
-		data["requestheader-uid-headers"], err = jsonSerializeStringSlice(authenticationInfo.RequestHeaderUIDHeaders.Value())
+		if utilfeature.DefaultFeatureGate.Enabled(features.RemoteRequestHeaderUID) && len(authenticationInfo.RequestHeaderUIDHeaders.Value()) > 0 {
-		if err != nil {
+			data["requestheader-uid-headers"], err = jsonSerializeStringSlice(authenticationInfo.RequestHeaderUIDHeaders.Value())
-			return nil, err
+			if err != nil {
+				return nil, err
+			}
 		}
+
 		data["requestheader-group-headers"], err = jsonSerializeStringSlice(authenticationInfo.RequestHeaderGroupHeaders.Value())
 		if err != nil {
 			return nil, err
@@ -305,9 +310,12 @@ func getClusterAuthenticationInfoFor(data map[string]string) (ClusterAuthenticat
 	if err != nil {
 		return ClusterAuthenticationInfo{}, err
 	}
-	ret.RequestHeaderUIDHeaders, err = jsonDeserializeStringSlice(data["requestheader-uid-headers"])
+
-	if err != nil {
+	if utilfeature.DefaultFeatureGate.Enabled(features.RemoteRequestHeaderUID) {
-		return ClusterAuthenticationInfo{}, err
+		ret.RequestHeaderUIDHeaders, err = jsonDeserializeStringSlice(data["requestheader-uid-headers"])
+		if err != nil {
+			return ClusterAuthenticationInfo{}, err
+		}
 	}
 
 	if caBundle := data["requestheader-client-ca-file"]; len(caBundle) > 0 {

pkg/features/versioned_kube_features.go

@@ -306,6 +306,10 @@ var defaultVersionedKubernetesFeatureGates = map[featuregate.Feature]featuregate
 		{Version: version.MustParse("1.29"), Default: true, PreRelease: featuregate.GA, LockToDefault: true},
 	},
 
+	genericfeatures.RemoteRequestHeaderUID: {
+		{Version: version.MustParse("1.32"), Default: false, PreRelease: featuregate.Alpha},
+	},
+
 	genericfeatures.ResilientWatchCacheInitialization: {
 		{Version: version.MustParse("1.31"), Default: true, PreRelease: featuregate.Beta},
 	},

staging/src/k8s.io/apiserver/pkg/features/kube_features.go

@@ -149,6 +149,13 @@ const (
 	// to a chunking list request.
 	RemainingItemCount featuregate.Feature = "RemainingItemCount"
 
+	// owner: @stlaz
+	//
+	// Enable kube-apiserver to accept UIDs via request header authentication.
+	// This will also make the kube-apiserver's API aggregator add UIDs via standard
+	// headers when forwarding requests to the servers serving the aggregated API.
+	RemoteRequestHeaderUID featuregate.Feature = "RemoteRequestHeaderUID"
+
 	// owner: @wojtek-t
 	//
 	// Enables resilient watchcache initialization to avoid controlplane
@@ -359,6 +366,10 @@ var defaultVersionedKubernetesFeatureGates = map[featuregate.Feature]featuregate
 		{Version: version.MustParse("1.29"), Default: true, PreRelease: featuregate.GA, LockToDefault: true},
 	},
 
+	RemoteRequestHeaderUID: {
+		{Version: version.MustParse("1.32"), Default: false, PreRelease: featuregate.Alpha},
+	},
+
 	ResilientWatchCacheInitialization: {
 		{Version: version.MustParse("1.31"), Default: true, PreRelease: featuregate.Beta},
 	},

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

@@ -29,8 +29,10 @@ import (
 	"k8s.io/apiserver/pkg/apis/apiserver"
 	"k8s.io/apiserver/pkg/authentication/authenticatorfactory"
 	"k8s.io/apiserver/pkg/authentication/request/headerrequest"
+	"k8s.io/apiserver/pkg/features"
 	"k8s.io/apiserver/pkg/server"
 	"k8s.io/apiserver/pkg/server/dynamiccertificates"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -68,9 +70,6 @@ func (s *RequestHeaderAuthenticationOptions) Validate() []error {
 	if err := checkForWhiteSpaceOnly("requestheader-username-headers", s.UsernameHeaders...); err != nil {
 		allErrors = append(allErrors, err)
 	}
-	if err := checkForWhiteSpaceOnly("requestheader-uid-headers", s.UIDHeaders...); err != nil {
-		allErrors = append(allErrors, err)
-	}
 	if err := checkForWhiteSpaceOnly("requestheader-group-headers", s.GroupHeaders...); err != nil {
 		allErrors = append(allErrors, err)
 	}
@@ -84,10 +83,6 @@ func (s *RequestHeaderAuthenticationOptions) Validate() []error {
 	if len(s.UsernameHeaders) > 0 && !caseInsensitiveHas(s.UsernameHeaders, "X-Remote-User") {
 		klog.Warningf("--requestheader-username-headers is set without specifying the standard X-Remote-User header - API aggregation will not work")
 	}
-	if len(s.UIDHeaders) > 0 && !caseInsensitiveHas(s.UIDHeaders, "X-Remote-Uid") {
-		// this was added later and so we are able to error out
-		allErrors = append(allErrors, fmt.Errorf("--requestheader-uid-headers is set without specifying the standard X-Remote-Uid header - API aggregation will not work"))
-	}
 	if len(s.GroupHeaders) > 0 && !caseInsensitiveHas(s.GroupHeaders, "X-Remote-Group") {
 		klog.Warningf("--requestheader-group-headers is set without specifying the standard X-Remote-Group header - API aggregation will not work")
 	}
@@ -95,6 +90,20 @@ func (s *RequestHeaderAuthenticationOptions) Validate() []error {
 		klog.Warningf("--requestheader-extra-headers-prefix is set without specifying the standard X-Remote-Extra- header prefix - API aggregation will not work")
 	}
 
+	if !utilfeature.DefaultFeatureGate.Enabled(features.RemoteRequestHeaderUID) {
+		if len(s.UIDHeaders) > 0 {
+			allErrors = append(allErrors, fmt.Errorf("--requestheader-uid-headers requires the %q feature to be enabled", features.RemoteRequestHeaderUID))
+		}
+	} else {
+		if err := checkForWhiteSpaceOnly("requestheader-uid-headers", s.UIDHeaders...); err != nil {
+			allErrors = append(allErrors, err)
+		}
+		if len(s.UIDHeaders) > 0 && !caseInsensitiveHas(s.UIDHeaders, "X-Remote-Uid") {
+			// this was added later and so we are able to error out
+			allErrors = append(allErrors, fmt.Errorf("--requestheader-uid-headers is set without specifying the standard X-Remote-Uid header - API aggregation will not work"))
+		}
+	}
+
 	return allErrors
 }
 
@@ -126,7 +135,7 @@ func (s *RequestHeaderAuthenticationOptions) AddFlags(fs *pflag.FlagSet) {
 		"List of request headers to inspect for usernames. X-Remote-User is common.")
 
 	fs.StringSliceVar(&s.UIDHeaders, "requestheader-uid-headers", s.UIDHeaders, ""+
-		"List of request headers to inspect for UIDs. X-Remote-Uid is suggested.")
+		"List of request headers to inspect for UIDs. X-Remote-Uid is suggested. Requires the RemoteRequestHeaderUID feature to be enabled.")
 
 	fs.StringSliceVar(&s.GroupHeaders, "requestheader-group-headers", s.GroupHeaders, ""+
 		"List of request headers to inspect for groups. X-Remote-Group is suggested.")

staging/src/k8s.io/kube-aggregator/pkg/apiserver/handler_proxy.go

@@ -159,7 +159,12 @@ func (r *proxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	proxyRoundTripper := handlingInfo.proxyRoundTripper
 	upgrade := httpstream.IsUpgradeRequest(req)
 
-	proxyRoundTripper = transport.NewAuthProxyRoundTripper(user.GetName(), user.GetUID(), user.GetGroups(), user.GetExtra(), proxyRoundTripper)
+	var userUID string
+	if utilfeature.DefaultFeatureGate.Enabled(genericfeatures.RemoteRequestHeaderUID) {
+		userUID = user.GetUID()
+	}
+
+	proxyRoundTripper = transport.NewAuthProxyRoundTripper(user.GetName(), userUID, user.GetGroups(), user.GetExtra(), proxyRoundTripper)
 
 	if utilfeature.DefaultFeatureGate.Enabled(genericfeatures.APIServerTracing) && !upgrade {
 		tracingWrapper := tracing.WrapperFor(r.tracerProvider)
@@ -170,7 +175,7 @@ func (r *proxyHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	// NOT use the proxyRoundTripper.  It's a direct dial that bypasses the proxyRoundTripper.  This means that we have to
 	// attach the "correct" user headers to the request ahead of time.
 	if upgrade {
-		transport.SetAuthProxyHeaders(newReq, user.GetName(), user.GetUID(), user.GetGroups(), user.GetExtra())
+		transport.SetAuthProxyHeaders(newReq, user.GetName(), userUID, user.GetGroups(), user.GetExtra())
 	}
 
 	handler := proxy.NewUpgradeAwareHandler(location, proxyRoundTripper, true, upgrade, &responder{w: w})

staging/src/k8s.io/kube-aggregator/pkg/apiserver/handler_proxy_test.go

@@ -34,7 +34,9 @@ import (
 	"sync/atomic"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	"k8s.io/apiserver/pkg/audit"
+	"k8s.io/apiserver/pkg/features"
 	"k8s.io/apiserver/pkg/server/dynamiccertificates"
 	"k8s.io/client-go/transport"
 
@@ -53,8 +55,11 @@ import (
 	"k8s.io/apiserver/pkg/endpoints/filters"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/apiserver/pkg/server/egressselector"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	utilflowcontrol "k8s.io/apiserver/pkg/util/flowcontrol"
 	apiserverproxyutil "k8s.io/apiserver/pkg/util/proxy"
+	"k8s.io/component-base/featuregate"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	"k8s.io/component-base/metrics"
 	"k8s.io/component-base/metrics/legacyregistry"
 	apiregistration "k8s.io/kube-aggregator/pkg/apis/apiregistration/v1"
@@ -130,6 +135,8 @@ func TestProxyHandler(t *testing.T) {
 		expectedBody       string
 		expectedCalled     bool
 		expectedHeaders    map[string][]string
+
+		enableFeatureGates []featuregate.Feature
 	}{
 		"no target": {
 			expectedStatusCode: http.StatusNotFound,
@@ -174,6 +181,40 @@ func TestProxyHandler(t *testing.T) {
 			},
 			expectedStatusCode: http.StatusOK,
 			expectedCalled:     true,
+			expectedHeaders: map[string][]string{
+				"X-Forwarded-Proto": {"https"},
+				"X-Forwarded-Uri":   {"/request/path"},
+				"X-Forwarded-For":   {"127.0.0.1"},
+				"X-Remote-User":     {"username"},
+				"User-Agent":        {"Go-http-client/1.1"},
+				"Accept-Encoding":   {"gzip"},
+				"X-Remote-Group":    {"one", "two"},
+			},
+		},
+		"[RemoteRequestHeaderUID] proxy with user, insecure": {
+			user: &user.DefaultInfo{
+				Name:   "username",
+				UID:    "6b60d791-1af9-4513-92e5-e4252a1e0a78",
+				Groups: []string{"one", "two"},
+			},
+			path: "/request/path",
+			apiService: &apiregistration.APIService{
+				ObjectMeta: metav1.ObjectMeta{Name: "v1.foo"},
+				Spec: apiregistration.APIServiceSpec{
+					Service:               &apiregistration.ServiceReference{Port: pointer.Int32Ptr(443)},
+					Group:                 "foo",
+					Version:               "v1",
+					InsecureSkipTLSVerify: true,
+				},
+				Status: apiregistration.APIServiceStatus{
+					Conditions: []apiregistration.APIServiceCondition{
+						{Type: apiregistration.Available, Status: apiregistration.ConditionTrue},
+					},
+				},
+			},
+			enableFeatureGates: []featuregate.Feature{features.RemoteRequestHeaderUID},
+			expectedStatusCode: http.StatusOK,
+			expectedCalled:     true,
 			expectedHeaders: map[string][]string{
 				"X-Forwarded-Proto": {"https"},
 				"X-Forwarded-Uri":   {"/request/path"},
@@ -208,6 +249,40 @@ func TestProxyHandler(t *testing.T) {
 			},
 			expectedStatusCode: http.StatusOK,
 			expectedCalled:     true,
+			expectedHeaders: map[string][]string{
+				"X-Forwarded-Proto": {"https"},
+				"X-Forwarded-Uri":   {"/request/path"},
+				"X-Forwarded-For":   {"127.0.0.1"},
+				"X-Remote-User":     {"username"},
+				"User-Agent":        {"Go-http-client/1.1"},
+				"Accept-Encoding":   {"gzip"},
+				"X-Remote-Group":    {"one", "two"},
+			},
+		},
+		"[RemoteRequestHeaderUID] proxy with user, cabundle": {
+			user: &user.DefaultInfo{
+				Name:   "username",
+				UID:    "6b60d791-1af9-4513-92e5-e4252a1e0a78",
+				Groups: []string{"one", "two"},
+			},
+			path: "/request/path",
+			apiService: &apiregistration.APIService{
+				ObjectMeta: metav1.ObjectMeta{Name: "v1.foo"},
+				Spec: apiregistration.APIServiceSpec{
+					Service:  &apiregistration.ServiceReference{Name: "test-service", Namespace: "test-ns", Port: pointer.Int32Ptr(443)},
+					Group:    "foo",
+					Version:  "v1",
+					CABundle: testCACrt,
+				},
+				Status: apiregistration.APIServiceStatus{
+					Conditions: []apiregistration.APIServiceCondition{
+						{Type: apiregistration.Available, Status: apiregistration.ConditionTrue},
+					},
+				},
+			},
+			enableFeatureGates: []featuregate.Feature{features.RemoteRequestHeaderUID},
+			expectedStatusCode: http.StatusOK,
+			expectedCalled:     true,
 			expectedHeaders: map[string][]string{
 				"X-Forwarded-Proto": {"https"},
 				"X-Forwarded-Uri":   {"/request/path"},
@@ -320,7 +395,11 @@ func TestProxyHandler(t *testing.T) {
 		target.Reset()
 		legacyregistry.Reset()
 
-		func() {
+		t.Run(name, func(t *testing.T) {
+			for _, f := range tc.enableFeatureGates {
+				featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, f, true)
+			}
+
 			targetServer := httptest.NewUnstartedServer(target)
 			serviceCert := tc.serviceCertOverride
 			if serviceCert == nil {
@@ -354,37 +433,37 @@ func TestProxyHandler(t *testing.T) {
 
 			resp, err := http.Get(server.URL + tc.path)
 			if err != nil {
-				t.Errorf("%s: %v", name, err)
+				t.Errorf("%v", err)
 				return
 			}
 			if e, a := tc.expectedStatusCode, resp.StatusCode; e != a {
 				body, _ := httputil.DumpResponse(resp, true)
-				t.Logf("%s: %v", name, string(body))
+				t.Logf("%v", string(body))
-				t.Errorf("%s: expected %v, got %v", name, e, a)
+				t.Errorf("expected %v, got %v", e, a)
 				return
 			}
 			bytes, err := io.ReadAll(resp.Body)
 			if err != nil {
-				t.Errorf("%s: %v", name, err)
+				t.Errorf("%v", err)
 				return
 			}
 			if !strings.Contains(string(bytes), tc.expectedBody) {
-				t.Errorf("%s: expected %q, got %q", name, tc.expectedBody, string(bytes))
+				t.Errorf("expected %q, got %q", tc.expectedBody, string(bytes))
 				return
 			}
 
 			if e, a := tc.expectedCalled, target.called; e != a {
-				t.Errorf("%s: expected %v, got %v", name, e, a)
+				t.Errorf("expected %v, got %v", e, a)
 				return
 			}
 			// this varies every test
 			delete(target.headers, "X-Forwarded-Host")
 			if e, a := tc.expectedHeaders, target.headers; !reflect.DeepEqual(e, a) {
-				t.Errorf("%s: expected %v, got %v", name, e, a)
+				t.Errorf("expected != got %v", cmp.Diff(e, a))
 				return
 			}
 			if e, a := targetServer.Listener.Addr().String(), target.host; tc.expectedCalled && !reflect.DeepEqual(e, a) {
-				t.Errorf("%s: expected %v, got %v", name, e, a)
+				t.Errorf("expected %v, got %v", e, a)
 				return
 			}
 
@@ -397,7 +476,7 @@ func TestProxyHandler(t *testing.T) {
 					t.Errorf("expected the x509_missing_san_total to be 1, but it's %d", errorCounter)
 				}
 			}
-		}()
+		})
 	}
 }