fix Envoy Fails to Add Router

internal/xds/translator/testdata/in/xds-ir/empty-hostnames.yaml

@@ -0,0 +1,10 @@
+name: "http-route"
+http:
+- name: "first-listener"
+  address: "0.0.0.0"
+  port: 10080
+  routes:
+  - name: "first-route" 
+    destinations:
+    - host: "1.2.3.4"
+      port: 50000

internal/xds/translator/testdata/out/xds-ir/empty-hostnames.clusters.yaml

@@ -0,0 +1,18 @@
+- commonLbConfig:
+    localityWeightedLbConfig: {}
+  connectTimeout: 5s
+  dnsLookupFamily: V4_ONLY
+  loadAssignment:
+    clusterName: cluster_first-route
+    endpoints:
+    - lbEndpoints:
+      - endpoint:
+          address:
+            socketAddress:
+              address: 1.2.3.4
+              portValue: 50000
+      loadBalancingWeight: 1
+      locality: {}
+  name: cluster_first-route
+  outlierDetection: {}
+  type: STATIC

internal/xds/translator/testdata/out/xds-ir/empty-hostnames.listeners.yaml

@@ -0,0 +1,26 @@
+- address:
+    socketAddress:
+      address: 0.0.0.0
+      portValue: 10080
+  filterChains:
+  - filters:
+    - name: envoy.filters.network.http_connection_manager
+      typedConfig:
+        '@type': type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
+        httpFilters:
+        - name: envoy.filters.http.router
+          typedConfig:
+            '@type': type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
+        rds:
+          configSource:
+            apiConfigSource:
+              apiType: GRPC
+              grpcServices:
+              - envoyGrpc:
+                  clusterName: xds_cluster
+              setNodeOnFirstMessageOnly: true
+              transportApiVersion: V3
+            resourceApiVersion: V3
+          routeConfigName: route_first-listener
+        statPrefix: http
+  name: listener_first-listener_10080

internal/xds/translator/testdata/out/xds-ir/empty-hostnames.routes.yaml

@@ -0,0 +1,10 @@
+- name: route_first-listener
+  virtualHosts:
+  - domains:
+    - '*'
+    name: route_first-listener
+    routes:
+    - match:
+        prefix: /
+      route:
+        cluster: cluster_first-route

internal/xds/translator/translator.go

@@ -52,6 +52,10 @@ func Translate(ir *ir.Xds) (*types.ResourceVersionTable, error) {
 			Domains: httpListener.Hostnames,
 		}
 
+		if len(vHost.Domains) == 0 {
+			vHost.Domains = []string{"*"}
+		}
+
 		for _, httpRoute := range httpListener.Routes {
 			// 1:1 between IR HTTPRoute and xDS config.route.v3.Route
 			xdsRoute, err := buildXdsRoute(httpRoute)

internal/xds/translator/translator_test.go

@@ -30,6 +30,9 @@ func TestTranslate(t *testing.T) {
 		{
 			name: "http-route",
 		},
+		{
+			name: "empty-hostnames",
+		},
 	}
 
 	for _, tc := range testCases {