fix: populate status for custom backendRef not found

internal/gatewayapi/route.go

@@ -1488,6 +1488,18 @@ func (t *Translator) processDestination(name string, backendRefContext BackendRe
 		if t.isCustomBackendResource(backendRef.Group, KindDerefOr(backendRef.Kind, resource.KindService)) {
 			// Add the custom backend resource to ExtensionRefFilters so it can be processed by the extension system
 			unstructuredRef = t.processBackendExtensions(backendRef.BackendObjectReference, backendNamespace, resources)
+
+			// Check if the custom backend resource was found
+			if unstructuredRef == nil {
+				return nil, nil, status.NewRouteStatusError(
+					fmt.Errorf("custom backend %s %s/%s not found",
+						KindDerefOr(backendRef.Kind, resource.KindService),
+						backendNamespace,
+						backendRef.Name),
+					gwapiv1.RouteReasonBackendNotFound,
+				).WithType(gwapiv1.RouteConditionResolvedRefs)
+			}
+
 			return &ir.DestinationSetting{
 				Name:            name,
 				Weight:          &weight,

internal/gatewayapi/testdata/extensions/httproute-with-custom-backend-invalid-apiversion.out.yaml

@@ -80,9 +80,11 @@ httpRoutes:
         status: "True"
         type: Accepted
       - lastTransitionTime: null
-        message: Resolved all the Object references for the Route
-        reason: ResolvedRefs
-        status: "True"
+        message: |-
+          Failed to process route rule 0 backendRef 0: custom backend S3Backend default/s3-backend not found.
+          Failed to process route rule 1 backendRef 0: custom backend LambdaBackend default/lambda-backend not found.
+        reason: BackendNotFound
+        status: "False"
         type: ResolvedRefs
       controllerName: gateway.envoyproxy.io/gatewayclass-controller
       parentRef:
@@ -145,16 +147,8 @@ xdsIR:
         mergeSlashes: true
       port: 10080
       routes:
-      - destination:
-          metadata:
-            kind: HTTPRoute
-            name: httproute-1
-            namespace: default
-          name: httproute/default/httproute-1/rule/1
-          settings:
-          - isCustomBackend: true
-            name: httproute/default/httproute-1/rule/1/backend/0
-            weight: 1
+      - directResponse:
+          statusCode: 500
         hostname: gateway.envoyproxy.io
         isHTTP2: false
         metadata:
@@ -166,16 +160,8 @@ xdsIR:
           distinct: false
           name: ""
           prefix: /lambda
-      - destination:
-          metadata:
-            kind: HTTPRoute
-            name: httproute-1
-            namespace: default
-          name: httproute/default/httproute-1/rule/0
-          settings:
-          - isCustomBackend: true
-            name: httproute/default/httproute-1/rule/0/backend/0
-            weight: 1
+      - directResponse:
+          statusCode: 500
         hostname: gateway.envoyproxy.io
         isHTTP2: false
         metadata:

internal/gatewayapi/testdata/extensions/httproute-with-custom-backend-not-found.in.yaml

@@ -0,0 +1,46 @@
+gateways:
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: Gateway
+  metadata:
+    namespace: envoy-gateway
+    name: gateway-1
+  spec:
+    gatewayClassName: envoy-gateway-class
+    listeners:
+    - name: http
+      protocol: HTTP
+      port: 80
+      hostname: "*.envoyproxy.io"
+      allowedRoutes:
+        namespaces:
+          from: All
+httpRoutes:
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: HTTPRoute
+  metadata:
+    namespace: default
+    name: httproute-1
+  spec:
+    hostnames:
+    - gateway.envoyproxy.io
+    parentRefs:
+    - namespace: envoy-gateway
+      name: gateway-1
+      sectionName: http
+    rules:
+    - matches:
+      - path:
+          value: "/s3"
+      backendRefs:
+      - group: storage.example.io
+        kind: S3Backend
+        name: s3-backend
+        port: 443
+    - matches:
+      - path:
+          value: "/lambda"
+      backendRefs:
+      - group: compute.example.io
+        kind: LambdaBackend
+        name: lambda-backend
+        port: 443

internal/gatewayapi/testdata/extensions/httproute-with-custom-backend-not-found.out.yaml

@@ -0,0 +1,180 @@
+gateways:
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: Gateway
+  metadata:
+    creationTimestamp: null
+    name: gateway-1
+    namespace: envoy-gateway
+  spec:
+    gatewayClassName: envoy-gateway-class
+    listeners:
+    - allowedRoutes:
+        namespaces:
+          from: All
+      hostname: '*.envoyproxy.io'
+      name: http
+      port: 80
+      protocol: HTTP
+  status:
+    listeners:
+    - attachedRoutes: 1
+      conditions:
+      - lastTransitionTime: null
+        message: Sending translated listener configuration to the data plane
+        reason: Programmed
+        status: "True"
+        type: Programmed
+      - lastTransitionTime: null
+        message: Listener has been successfully translated
+        reason: Accepted
+        status: "True"
+        type: Accepted
+      - lastTransitionTime: null
+        message: Listener references have been resolved
+        reason: ResolvedRefs
+        status: "True"
+        type: ResolvedRefs
+      name: http
+      supportedKinds:
+      - group: gateway.networking.k8s.io
+        kind: HTTPRoute
+      - group: gateway.networking.k8s.io
+        kind: GRPCRoute
+httpRoutes:
+- apiVersion: gateway.networking.k8s.io/v1
+  kind: HTTPRoute
+  metadata:
+    creationTimestamp: null
+    name: httproute-1
+    namespace: default
+  spec:
+    hostnames:
+    - gateway.envoyproxy.io
+    parentRefs:
+    - name: gateway-1
+      namespace: envoy-gateway
+      sectionName: http
+    rules:
+    - backendRefs:
+      - group: storage.example.io
+        kind: S3Backend
+        name: s3-backend
+        port: 443
+      matches:
+      - path:
+          value: /s3
+    - backendRefs:
+      - group: compute.example.io
+        kind: LambdaBackend
+        name: lambda-backend
+        port: 443
+      matches:
+      - path:
+          value: /lambda
+  status:
+    parents:
+    - conditions:
+      - lastTransitionTime: null
+        message: Route is accepted
+        reason: Accepted
+        status: "True"
+        type: Accepted
+      - lastTransitionTime: null
+        message: |-
+          Failed to process route rule 0 backendRef 0: custom backend S3Backend default/s3-backend not found.
+          Failed to process route rule 1 backendRef 0: custom backend LambdaBackend default/lambda-backend not found.
+        reason: BackendNotFound
+        status: "False"
+        type: ResolvedRefs
+      controllerName: gateway.envoyproxy.io/gatewayclass-controller
+      parentRef:
+        name: gateway-1
+        namespace: envoy-gateway
+        sectionName: http
+infraIR:
+  envoy-gateway/gateway-1:
+    proxy:
+      listeners:
+      - address: null
+        name: envoy-gateway/gateway-1/http
+        ports:
+        - containerPort: 10080
+          name: http-80
+          protocol: HTTP
+          servicePort: 80
+      metadata:
+        labels:
+          gateway.envoyproxy.io/owning-gateway-name: gateway-1
+          gateway.envoyproxy.io/owning-gateway-namespace: envoy-gateway
+        ownerReference:
+          kind: GatewayClass
+          name: envoy-gateway-class
+      name: envoy-gateway/gateway-1
+      namespace: ""
+xdsIR:
+  envoy-gateway/gateway-1:
+    accessLog:
+      json:
+      - path: /dev/stdout
+    globalResources:
+      proxyServiceCluster:
+        name: envoy-gateway/gateway-1
+        settings:
+        - addressType: IP
+          endpoints:
+          - host: 7.6.5.4
+            port: 8080
+            zone: zone1
+          metadata:
+            name: envoy-envoy-gateway-gateway-1-196ae069
+            sectionName: "8080"
+          name: envoy-gateway/gateway-1
+          protocol: TCP
+    http:
+    - address: 0.0.0.0
+      externalPort: 80
+      hostnames:
+      - '*.envoyproxy.io'
+      isHTTP2: false
+      metadata:
+        kind: Gateway
+        name: gateway-1
+        namespace: envoy-gateway
+        sectionName: http
+      name: envoy-gateway/gateway-1/http
+      path:
+        escapedSlashesAction: UnescapeAndRedirect
+        mergeSlashes: true
+      port: 10080
+      routes:
+      - directResponse:
+          statusCode: 500
+        hostname: gateway.envoyproxy.io
+        isHTTP2: false
+        metadata:
+          kind: HTTPRoute
+          name: httproute-1
+          namespace: default
+        name: httproute/default/httproute-1/rule/1/match/0/gateway_envoyproxy_io
+        pathMatch:
+          distinct: false
+          name: ""
+          prefix: /lambda
+      - directResponse:
+          statusCode: 500
+        hostname: gateway.envoyproxy.io
+        isHTTP2: false
+        metadata:
+          kind: HTTPRoute
+          name: httproute-1
+          namespace: default
+        name: httproute/default/httproute-1/rule/0/match/0/gateway_envoyproxy_io
+        pathMatch:
+          distinct: false
+          name: ""
+          prefix: /s3
+    readyListener:
+      address: 0.0.0.0
+      ipFamily: IPv4
+      path: /ready
+      port: 19003