fix: only watch L4RoutePolicy when its CRD is installed

The TCP/UDP/TLSRoute controllers watched L4RoutePolicy unconditionally, so
upgrading the controller without applying the new CRD made the manager fail
to start (the informer cannot be created for a missing kind), taking down all
routing. Guard the watch with HasAPIResource so the controller starts without
the CRD and enables L4RoutePolicy once it is installed and the pod restarts,
matching how optional resources like EndpointSlice are handled.

Author: AlinsRan

internal/controller/tcproute_controller.go

@@ -45,6 +45,7 @@ import (
 	"github.com/apache/apisix-ingress-controller/internal/provider"
 	"github.com/apache/apisix-ingress-controller/internal/types"
 	"github.com/apache/apisix-ingress-controller/internal/utils"
+	pkgutils "github.com/apache/apisix-ingress-controller/pkg/utils"
 )
 
 // TCPRouteReconciler reconciles a TCPRoute object.
@@ -93,10 +94,15 @@ func (r *TCPRouteReconciler) SetupWithManager(mgr ctrl.Manager) error {
 		).
 		Watches(&v1alpha1.GatewayProxy{},
 			handler.EnqueueRequestsFromMapFunc(r.listTCPRoutesForGatewayProxy),
-		).
-		Watches(&v1alpha1.L4RoutePolicy{},
+		)
+
+	// L4RoutePolicy is an optional CRD. Only watch it when installed so the
+	// controller still starts if the CRD has not been applied yet (e.g. upgrades).
+	if pkgutils.HasAPIResource(mgr, &v1alpha1.L4RoutePolicy{}) {
+		bdr.Watches(&v1alpha1.L4RoutePolicy{},
 			handler.EnqueueRequestsFromMapFunc(r.listTCPRoutesForL4RoutePolicy),
 		)
+	}
 
 	if GetEnableReferenceGrant() {
 		bdr.Watches(&v1beta1.ReferenceGrant{},

internal/controller/tlsroute_controller.go

@@ -45,6 +45,7 @@ import (
 	"github.com/apache/apisix-ingress-controller/internal/provider"
 	"github.com/apache/apisix-ingress-controller/internal/types"
 	"github.com/apache/apisix-ingress-controller/internal/utils"
+	pkgutils "github.com/apache/apisix-ingress-controller/pkg/utils"
 )
 
 // TLSRouteReconciler reconciles a TLSRoute object.
@@ -93,10 +94,15 @@ func (r *TLSRouteReconciler) SetupWithManager(mgr ctrl.Manager) error {
 		).
 		Watches(&v1alpha1.GatewayProxy{},
 			handler.EnqueueRequestsFromMapFunc(r.listTLSRoutesForGatewayProxy),
-		).
-		Watches(&v1alpha1.L4RoutePolicy{},
+		)
+
+	// L4RoutePolicy is an optional CRD. Only watch it when installed so the
+	// controller still starts if the CRD has not been applied yet (e.g. upgrades).
+	if pkgutils.HasAPIResource(mgr, &v1alpha1.L4RoutePolicy{}) {
+		bdr.Watches(&v1alpha1.L4RoutePolicy{},
 			handler.EnqueueRequestsFromMapFunc(r.listTLSRoutesForL4RoutePolicy),
 		)
+	}
 
 	if GetEnableReferenceGrant() {
 		bdr.Watches(&v1beta1.ReferenceGrant{},

internal/controller/udproute_controller.go

@@ -45,6 +45,7 @@ import (
 	"github.com/apache/apisix-ingress-controller/internal/provider"
 	"github.com/apache/apisix-ingress-controller/internal/types"
 	"github.com/apache/apisix-ingress-controller/internal/utils"
+	pkgutils "github.com/apache/apisix-ingress-controller/pkg/utils"
 )
 
 // UDPRouteReconciler reconciles a UDPRoute object.
@@ -93,10 +94,15 @@ func (r *UDPRouteReconciler) SetupWithManager(mgr ctrl.Manager) error {
 		).
 		Watches(&v1alpha1.GatewayProxy{},
 			handler.EnqueueRequestsFromMapFunc(r.listUDPRoutesForGatewayProxy),
-		).
-		Watches(&v1alpha1.L4RoutePolicy{},
+		)
+
+	// L4RoutePolicy is an optional CRD. Only watch it when installed so the
+	// controller still starts if the CRD has not been applied yet (e.g. upgrades).
+	if pkgutils.HasAPIResource(mgr, &v1alpha1.L4RoutePolicy{}) {
+		bdr.Watches(&v1alpha1.L4RoutePolicy{},
 			handler.EnqueueRequestsFromMapFunc(r.listUDPRoutesForL4RoutePolicy),
 		)
+	}
 
 	if GetEnableReferenceGrant() {
 		bdr.Watches(&v1beta1.ReferenceGrant{},