update service configuration to use host.docker.internal for backend connectivity

new-backend/docker-compose.tunnel.yml

@@ -4,11 +4,13 @@ services:
       context: .
       dockerfile: Dockerfile.tunnel
     restart: unless-stopped
+    extra_hosts:
+      - "host.docker.internal:host-gateway"
     volumes:
       - //var/run/docker.sock:/var/run/docker.sock
-    # Port is only exposed locally, traffic comes through the tunnel
-    ports:
-      - "127.0.0.1:8080:8080"
+    # No need to expose ports - traffic comes through the tunnel
+    # ports:
+    #   - "127.0.0.1:8080:8080"
     environment:
       - PORT=8080
       - CONCURRENT_EXECUTIONS=5