feat(apigatewayv2): allow websockets routes to return response to client

packages/@aws-cdk/aws-apigatewayv2/lib/websocket/route.ts

@@ -1,6 +1,6 @@
 import { Resource } from '@aws-cdk/core';
 import { Construct } from 'constructs';
-import { CfnRoute } from '../apigatewayv2.generated';
+import { CfnRoute, CfnRouteResponse } from '../apigatewayv2.generated';
 import { IRoute } from '../common';
 import { IWebSocketApi } from './api';
 import { IWebSocketRouteAuthorizer, WebSocketNoneAuthorizer } from './authorizer';
@@ -37,6 +37,13 @@ export interface WebSocketRouteOptions {
    * @default - No Authorizer
    */
   readonly authorizer?: IWebSocketRouteAuthorizer;
+
+  /**
+   * Should the route send a response to the client
+   * @default false
+   */
+  readonly shouldReturnResponse?: boolean;
+
 }
 
 /**
@@ -102,7 +109,15 @@ export class WebSocketRoute extends Resource implements IWebSocketRoute {
       target: `integrations/${config.integrationId}`,
       authorizerId: authBindResult.authorizerId,
       authorizationType: authBindResult.authorizationType,
+      routeResponseSelectionExpression: props.shouldReturnResponse ? '$default' : undefined,
     });
     this.routeId = route.ref;
+    if (props.shouldReturnResponse) {
+      new CfnRouteResponse(this, 'Response', {
+        apiId: props.webSocketApi.apiId,
+        routeId: route.ref,
+        routeResponseKey: '$default',
+      });
+    }
   }
 }

packages/@aws-cdk/aws-apigatewayv2/test/websocket/api.test.ts

@@ -65,6 +65,28 @@ describe('WebSocketApi', () => {
     });
   });
 
+  test('addRoute: adds a route with passed key and allows it to return a response', () => {
+    // GIVEN
+    const stack = new Stack();
+    const api = new WebSocketApi(stack, 'api');
+
+    // WHEN
+    const route = api.addRoute('myroute', { integration: new DummyIntegration(), shouldReturnResponse: true });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::ApiGatewayV2::Route', {
+      ApiId: stack.resolve(api.apiId),
+      RouteKey: 'myroute',
+      RouteResponseSelectionExpression: '$default',
+    });
+
+    Template.fromStack(stack).hasResourceProperties('AWS::ApiGatewayV2::RouteResponse', {
+      ApiId: stack.resolve(api.apiId),
+      RouteId: stack.resolve(route.routeId),
+      RouteResponseKey: '$default',
+    });
+  });
+
   test('connectRouteOptions: adds a $connect route', () => {
     // GIVEN
     const stack = new Stack();

packages/@aws-cdk/aws-apigatewayv2/test/websocket/route.test.ts

@@ -120,6 +120,50 @@ describe('WebSocketRoute', () => {
 
     Template.fromStack(stack).hasResource('AWS::ApiGatewayV2::Integration', 2);
   });
+
+  test('default RouteResponseSelectionExpression is set if route will return a response to the client', () => {
+    // GIVEN
+    const stack = new Stack();
+    const webSocketApi = new WebSocketApi(stack, 'Api');
+
+    // WHEN
+    const route = new WebSocketRoute(stack, 'Route', {
+      webSocketApi,
+      integration: new DummyIntegration(),
+      routeKey: 'message',
+      shouldReturnResponse: true,
+    });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::ApiGatewayV2::Route', {
+      ApiId: stack.resolve(webSocketApi.apiId),
+      RouteKey: 'message',
+      RouteResponseSelectionExpression: '$default',
+      Target: {
+        'Fn::Join': [
+          '',
+          [
+            'integrations/',
+            {
+              Ref: 'RouteDummyIntegrationE40E82B4',
+            },
+          ],
+        ],
+      },
+    });
+
+    Template.fromStack(stack).hasResourceProperties('AWS::ApiGatewayV2::RouteResponse', {
+      ApiId: stack.resolve(webSocketApi.apiId),
+      RouteId: stack.resolve(route.routeId),
+      RouteResponseKey: '$default',
+    });
+
+    Template.fromStack(stack).hasResourceProperties('AWS::ApiGatewayV2::Integration', {
+      ApiId: stack.resolve(webSocketApi.apiId),
+      IntegrationType: 'AWS_PROXY',
+      IntegrationUri: 'some-uri',
+    });
+  });
 });