feat: use grpc status errors in jwtinterceptor

internal/xds/server/kubejwt/jwtinterceptor.go

@@ -7,12 +7,13 @@ package kubejwt
 
 import (
 	"context"
-	"fmt"
 	"strings"
 
 	discoveryv3 "github.com/envoyproxy/go-control-plane/envoy/service/discovery/v3"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
 	"k8s.io/client-go/kubernetes"
 
 	"github.com/envoyproxy/gateway/internal/logging"
@@ -51,18 +52,20 @@ func (i *JWTAuthInterceptor) authenticate(ctx context.Context, msg any) error {
 
 	md, ok := metadata.FromIncomingContext(ctx)
 	if !ok {
-		return fmt.Errorf("missing metadata")
+		return status.Errorf(codes.Unauthenticated, "missing metadata for node %s", nodeID)
 	}
 
 	authHeader := md.Get("authorization")
 	if len(authHeader) == 0 {
-		return fmt.Errorf("missing authorization token in metadata: %s", md)
+		return status.Errorf(codes.Unauthenticated, "missing authorization header for node %s", nodeID)
 	}
 	token := strings.TrimPrefix(authHeader[0], "Bearer ")
 
 	if err := i.validateKubeJWT(ctx, token, nodeID); err != nil {
-		i.logger.Error(err, "failed to validate token")
-		return fmt.Errorf("failed to validate token: %w", err)
+		if s, ok := status.FromError(err); ok {
+			return status.Errorf(s.Code(), "failed to validate the token for node %s: %s", nodeID, s.Message())
+		}
+		return status.Errorf(codes.Unauthenticated, "failed to validate the token for node %s: %v", nodeID, err)
 	}
 
 	return nil
@@ -109,15 +112,15 @@ func extractNodeID(m any) (string, error) {
 	switch req := m.(type) {
 	case *discoveryv3.DeltaDiscoveryRequest:
 		if req.Node == nil || req.Node.Id == "" {
-			return "", fmt.Errorf("missing node ID")
+			return "", status.Error(codes.InvalidArgument, "missing node ID")
 		}
 		return req.Node.Id, nil
 	case *discoveryv3.DiscoveryRequest:
 		if req.Node == nil || req.Node.Id == "" {
-			return "", fmt.Errorf("missing node ID")
+			return "", status.Error(codes.InvalidArgument, "missing node ID")
 		}
 		return req.Node.Id, nil
 	default:
-		return "", fmt.Errorf("unexpected message type: %T", m)
+		return "", status.Errorf(codes.InvalidArgument, "unexpected message type: %T", m)
 	}
 }

internal/xds/server/kubejwt/jwtinterceptor_test.go

@@ -16,7 +16,9 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
+	"google.golang.org/grpc/status"
 
 	egv1a1 "github.com/envoyproxy/gateway/api/v1alpha1"
 	"github.com/envoyproxy/gateway/internal/logging"
@@ -42,85 +44,96 @@ func (m *mockServerStream) RecvMsg(_ any) error      { return nil }
 // authTestCase defines a single test case for the authenticate method.
 // The same cases are run against both the stream (RecvMsg) and unary interceptor paths.
 type authTestCase struct {
-	name    string
-	msg     any
-	ctx     context.Context
-	wantErr string
+	name     string
+	msg      any
+	ctx      context.Context
+	wantErr  string
+	wantCode codes.Code
 }
 
 func authTestCases() []authTestCase {
 	return []authTestCase{
 		{
-			name:    "unknown message type is rejected (fail-closed)",
-			msg:     &discoveryv3.DiscoveryResponse{},
-			ctx:     context.Background(),
-			wantErr: "unexpected message type",
+			name:     "unknown message type is rejected (fail-closed)",
+			msg:      &discoveryv3.DiscoveryResponse{},
+			ctx:      context.Background(),
+			wantErr:  "unexpected message type",
+			wantCode: codes.InvalidArgument,
 		},
 		{
-			name:    "nil message is rejected",
-			msg:     nil,
-			ctx:     context.Background(),
-			wantErr: "unexpected message type",
+			name:     "nil message is rejected",
+			msg:      nil,
+			ctx:      context.Background(),
+			wantErr:  "unexpected message type",
+			wantCode: codes.InvalidArgument,
 		},
 		{
-			name:    "DeltaDiscoveryRequest with nil node is rejected",
-			msg:     &discoveryv3.DeltaDiscoveryRequest{},
-			ctx:     context.Background(),
-			wantErr: "missing node ID",
+			name:     "DeltaDiscoveryRequest with nil node is rejected",
+			msg:      &discoveryv3.DeltaDiscoveryRequest{},
+			ctx:      context.Background(),
+			wantErr:  "missing node ID",
+			wantCode: codes.InvalidArgument,
 		},
 		{
-			name:    "DiscoveryRequest with nil node is rejected",
-			msg:     &discoveryv3.DiscoveryRequest{},
-			ctx:     context.Background(),
-			wantErr: "missing node ID",
+			name:     "DiscoveryRequest with nil node is rejected",
+			msg:      &discoveryv3.DiscoveryRequest{},
+			ctx:      context.Background(),
+			wantErr:  "missing node ID",
+			wantCode: codes.InvalidArgument,
 		},
 		{
 			name: "DeltaDiscoveryRequest with empty node ID is rejected",
 			msg: &discoveryv3.DeltaDiscoveryRequest{
 				Node: &corev3.Node{Id: ""},
 			},
-			ctx:     context.Background(),
-			wantErr: "missing node ID",
+			ctx:      context.Background(),
+			wantErr:  "missing node ID",
+			wantCode: codes.InvalidArgument,
 		},
 		{
 			name: "DiscoveryRequest with empty node ID is rejected",
 			msg: &discoveryv3.DiscoveryRequest{
 				Node: &corev3.Node{Id: ""},
 			},
-			ctx:     context.Background(),
-			wantErr: "missing node ID",
+			ctx:      context.Background(),
+			wantErr:  "missing node ID",
+			wantCode: codes.InvalidArgument,
 		},
 		{
 			name: "DeltaDiscoveryRequest without metadata is rejected",
 			msg: &discoveryv3.DeltaDiscoveryRequest{
 				Node: &corev3.Node{Id: "pod-1"},
 			},
-			ctx:     context.Background(),
-			wantErr: "missing metadata",
+			ctx:      context.Background(),
+			wantErr:  "missing metadata",
+			wantCode: codes.Unauthenticated,
 		},
 		{
 			name: "DiscoveryRequest without metadata is rejected",
 			msg: &discoveryv3.DiscoveryRequest{
 				Node: &corev3.Node{Id: "pod-1"},
 			},
-			ctx:     context.Background(),
-			wantErr: "missing metadata",
+			ctx:      context.Background(),
+			wantErr:  "missing metadata",
+			wantCode: codes.Unauthenticated,
 		},
 		{
 			name: "DeltaDiscoveryRequest without auth header is rejected",
 			msg: &discoveryv3.DeltaDiscoveryRequest{
 				Node: &corev3.Node{Id: "pod-1"},
 			},
-			ctx:     metadata.NewIncomingContext(context.Background(), metadata.MD{}),
-			wantErr: "missing authorization token",
+			ctx:      metadata.NewIncomingContext(context.Background(), metadata.MD{}),
+			wantErr:  "missing authorization header",
+			wantCode: codes.Unauthenticated,
 		},
 		{
 			name: "DiscoveryRequest without auth header is rejected",
 			msg: &discoveryv3.DiscoveryRequest{
 				Node: &corev3.Node{Id: "pod-1"},
 			},
-			ctx:     metadata.NewIncomingContext(context.Background(), metadata.MD{}),
-			wantErr: "missing authorization token",
+			ctx:      metadata.NewIncomingContext(context.Background(), metadata.MD{}),
+			wantErr:  "missing authorization header",
+			wantCode: codes.Unauthenticated,
 		},
 	}
 }
@@ -141,6 +154,7 @@ func TestAuthenticate_Stream(t *testing.T) {
 			err := ws.RecvMsg(tt.msg)
 			require.Error(t, err)
 			assert.Contains(t, err.Error(), tt.wantErr)
+			assert.Equal(t, tt.wantCode, status.Code(err), "unexpected gRPC status code")
 		})
 	}
 }
@@ -157,6 +171,7 @@ func TestAuthenticate_Unary(t *testing.T) {
 			_, err := unary(tt.ctx, tt.msg, &grpc.UnaryServerInfo{}, handler)
 			require.Error(t, err)
 			assert.Contains(t, err.Error(), tt.wantErr)
+			assert.Equal(t, tt.wantCode, status.Code(err), "unexpected gRPC status code")
 		})
 	}
 }

internal/xds/server/kubejwt/tokenreview.go

@@ -10,6 +10,8 @@ import (
 	"fmt"
 	"slices"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 	authenticationv1 "k8s.io/api/authentication/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apiserver/pkg/authentication/serviceaccount"
@@ -42,31 +44,31 @@ func (i *JWTAuthInterceptor) validateKubeJWT(ctx context.Context, token, nodeID
 
 	tokenReview, err := i.clientset.AuthenticationV1().TokenReviews().Create(ctx, tokenReview, metav1.CreateOptions{})
 	if err != nil {
-		return fmt.Errorf("failed to call TokenReview API to verify service account JWT: %w", err)
+		return status.Errorf(codes.Internal, "failed to call TokenReview API to verify service account JWT: %v", err)
 	}
 
 	if tokenReview.Status.Error != "" {
-		return fmt.Errorf("token review found error: %s", tokenReview.Status.Error)
+		return status.Errorf(codes.Unauthenticated, "token review found error: %s", tokenReview.Status.Error)
 	}
 
 	if !slices.Contains(tokenReview.Status.User.Groups, "system:serviceaccounts") {
-		return fmt.Errorf("the token is not a service account")
+		return status.Error(codes.Unauthenticated, "the token is not a service account")
 	}
 
 	if !tokenReview.Status.Authenticated {
-		return fmt.Errorf("token is not authenticated")
+		return status.Error(codes.Unauthenticated, "token is not authenticated")
 	}
 
 	// Check if the node ID in the request matches the pod name in the token review response.
 	// This is used to prevent a client from accessing the xDS resource of another one.
 	if tokenReview.Status.User.Extra != nil {
 		podName := tokenReview.Status.User.Extra[serviceaccount.PodNameKey]
 		if podName[0] == "" {
-			return fmt.Errorf("pod name not found in token review response")
+			return status.Error(codes.Unauthenticated, "pod name not found in token review response")
 		}
 
 		if podName[0] != nodeID {
-			return fmt.Errorf("pod name mismatch: expected %s, got %s", nodeID, podName[0])
+			return status.Errorf(codes.Unauthenticated, "pod name mismatch: expected %s, got %s", nodeID, podName[0])
 		}
 	}