fix(translator): Early status push for headless Service

internal/gatewayapi/route.go

@@ -1401,6 +1401,11 @@ func validateDestinationSettings(destinationSettings *ir.DestinationSetting, end
 				status.RouteReasonUnsupportedAddressType)
 		}
 	case resource.KindService, resource.KindServiceImport:
+		if endpointRoutingDisabled && isHeadlessService(destinationSettings) {
+			return status.NewRouteStatusError(
+				fmt.Errorf("service %s is headless Service, please set routingType=Endpoint", destinationSettings.Name),
+				status.RouteReasonUnsupportedSetting)
+		}
 		if !endpointRoutingDisabled && destinationSettings.AddressType != nil && *destinationSettings.AddressType == ir.MIXED {
 			return status.NewRouteStatusError(
 				fmt.Errorf("mixed endpointslice address type for the same backendRef is not supported"),
@@ -1411,6 +1416,17 @@ func validateDestinationSettings(destinationSettings *ir.DestinationSetting, end
 	return nil
 }
 
+// isHeadlessService reports true when any DestinationEndpoint corresponds to
+// a headless Kubernetes Service (ClusterIP="None").
+func isHeadlessService(ds *ir.DestinationSetting) bool {
+	for _, ep := range ds.Endpoints {
+		if ep.Host == "None" {
+			return true
+		}
+	}
+	return false
+}
+
 func (t *Translator) processServiceImportDestinationSetting(
 	name string,
 	backendRef gwapiv1.BackendObjectReference,

internal/gatewayapi/route_test.go

@@ -14,7 +14,10 @@ import (
 	discoveryv1 "k8s.io/api/discovery/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/utils/ptr"
+	gwapiv1 "sigs.k8s.io/gateway-api/apis/v1"
 
+	"github.com/envoyproxy/gateway/internal/gatewayapi/resource"
+	"github.com/envoyproxy/gateway/internal/gatewayapi/status"
 	"github.com/envoyproxy/gateway/internal/ir"
 )
 
@@ -226,3 +229,98 @@ func TestGetIREndpointsFromEndpointSlices(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateDestinationSettings(t *testing.T) {
+	svcKind := gwapiv1.Kind(resource.KindService)
+
+	tests := []struct {
+		name                    string
+		ds                      *ir.DestinationSetting
+		endpointRoutingDisabled bool
+		kind                    *gwapiv1.Kind
+		wantErr                 bool
+		wantReason              gwapiv1.RouteConditionReason
+	}{
+		{
+			name: "headless service rejected when endpointRoutingDisabled=true",
+			ds: &ir.DestinationSetting{
+				Name:      "headless",
+				Endpoints: []*ir.DestinationEndpoint{{Host: "None"}},
+			},
+			endpointRoutingDisabled: true,
+			kind:                    &svcKind,
+			wantErr:                 true,
+			wantReason:              status.RouteReasonUnsupportedSetting,
+		},
+		{
+			name: "normal service allowed with ClusterIP routing",
+			ds: &ir.DestinationSetting{
+				Name:      "normal",
+				Endpoints: []*ir.DestinationEndpoint{{Host: "10.0.0.1"}},
+			},
+			endpointRoutingDisabled: true,
+			kind:                    &svcKind,
+			wantErr:                 false,
+		},
+		{
+			name: "mixed address type rejected when EndpointSlice routing",
+			ds: &ir.DestinationSetting{
+				Name:        "mixed",
+				Endpoints:   []*ir.DestinationEndpoint{{Host: "10.0.0.1"}},
+				AddressType: ptr.To(ir.MIXED),
+			},
+			endpointRoutingDisabled: false,
+			kind:                    &svcKind,
+			wantErr:                 true,
+			wantReason:              status.RouteReasonUnsupportedAddressType,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := validateDestinationSettings(tt.ds, tt.endpointRoutingDisabled, tt.kind)
+			if tt.wantErr {
+				require.Error(t, err)
+				require.Equal(t, tt.wantReason, err.Reason())
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestIsHeadlessService(t *testing.T) {
+	tests := []struct {
+		name      string
+		endpoints []*ir.DestinationEndpoint
+		want      bool
+	}{
+		{
+			name: "headless Service",
+			endpoints: []*ir.DestinationEndpoint{
+				{Host: "None"},
+			},
+			want: true,
+		},
+		{
+			name: "non headless Service with valid ClusterIP",
+			endpoints: []*ir.DestinationEndpoint{
+				{Host: "10.0.0.1"},
+			},
+			want: false,
+		},
+		{
+			name:      "empty slice",
+			endpoints: nil,
+			want:      false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ds := &ir.DestinationSetting{Endpoints: tt.endpoints}
+			got := isHeadlessService(ds)
+			require.Equal(t, tt.want, got)
+		})
+	}
+}