fix(apigatewayv2): integration class does not render an integration resource (#17729)

Routes on APIGateway V2 can integrate with different backends. This is
achieved by creating the CFN resource `AWS::ApiGatewayV2::Integration`
that is then referenced in the resource for the Route.

Currently, the `IHttpRouteIntegration` (and `IWebSocketRouteIntegration`)
interface represents a unique backend that a route can integrate with,
using the CDK "bind" pattern.
An integration can be bound to any number of routes but should be
rendered into a single instance of `AWS::ApiGatewayV2::Integration`
resource.
To achieve this currently, the `HttpApi` (and `WebSocketApi`) class
holds a cache of all integrations defined against its routes.

This is the wrong level of caching and causes a number of problems.

1. We rely on the configuration of the `AWS::ApiGateway::Integration`
   resource to determine if one already exists.
   This means that two instances of `IHttpRouteIntegration` can result
   in rendering only one instance of `AWS::ApiGateway::Integration`
   resource.

   Users may want to intentionally generate multiple instances of
   `AWS::ApiGateway::Integration` classes with the same configuration.
   Taking away this power with CDK "magic" is just confusing.

2. Currently, we allow using the same instance of
   `IHttpRouteIntegration` (or `IWebSocketRouteIntegration`) to be bound
   to routes in different `HttpApi`. When bound to the route, the CDK
   renders an instance of `AWS::ApiGatewayV2::Integration` for each API.

   This is another "magic" that has the potential for user confusion and
   bugs.

The solution is to KeepItSimple™.

Remove the API level caching and simply cache at the level of each
integration. This ensures that each instance of `HttpRouteIntegration`
(previously `IHttpRouteIntegration`) renders to exactly one instance of
`AWS::ApiGatewayV2::Integration`.

Disallow using the same instance of `HttpRouteIntegration` across
different instances of `HttpApi`.

fixes #13213

BREAKING CHANGE: The interface `IHttpRouteIntegration` is replaced by
the abstract class `HttpRouteIntegration`.
* **apigatewayv2:** The interface `IWebSocketRouteIntegration` is now
  replaced by the abstract class `WebSocketRouteIntegration`.
* **apigatewayv2:** Previously, we allowed the usage of integration
  classes to be used with routes defined in multiple `HttpApi` instances
  (or `WebSocketApi` instances). This is now disallowed, and separate
  instances must be created for each instance of `HttpApi` or
  `WebSocketApi`.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: Niranjan Jayakar

packages/@aws-cdk/aws-apigatewayv2-authorizers/test/http/jwt.test.ts

@@ -1,5 +1,5 @@
 import { Template } from '@aws-cdk/assertions';
-import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, IHttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
+import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, HttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
 import { Stack } from '@aws-cdk/core';
 import { HttpJwtAuthorizer } from '../../lib';
 
@@ -59,7 +59,7 @@ describe('HttpJwtAuthorizer', () => {
   });
 });
 
-class DummyRouteIntegration implements IHttpRouteIntegration {
+class DummyRouteIntegration extends HttpRouteIntegration {
   public bind(_: HttpRouteIntegrationBindOptions) {
     return {
       payloadFormatVersion: PayloadFormatVersion.VERSION_2_0,

packages/@aws-cdk/aws-apigatewayv2-authorizers/test/http/lambda.test.ts

@@ -1,5 +1,5 @@
 import { Match, Template } from '@aws-cdk/assertions';
-import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, IHttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
+import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, HttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
 import { Code, Function, Runtime } from '@aws-cdk/aws-lambda';
 import { Duration, Stack } from '@aws-cdk/core';
 import { HttpLambdaAuthorizer, HttpLambdaResponseType } from '../../lib';
@@ -170,7 +170,7 @@ describe('HttpLambdaAuthorizer', () => {
   });
 });
 
-class DummyRouteIntegration implements IHttpRouteIntegration {
+class DummyRouteIntegration extends HttpRouteIntegration {
   public bind(_: HttpRouteIntegrationBindOptions) {
     return {
       payloadFormatVersion: PayloadFormatVersion.VERSION_2_0,

packages/@aws-cdk/aws-apigatewayv2-authorizers/test/http/user-pool.test.ts

@@ -1,5 +1,5 @@
 import { Template } from '@aws-cdk/assertions';
-import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, IHttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
+import { HttpApi, HttpIntegrationType, HttpRouteIntegrationBindOptions, HttpRouteIntegration, PayloadFormatVersion } from '@aws-cdk/aws-apigatewayv2';
 import { UserPool } from '@aws-cdk/aws-cognito';
 import { Stack } from '@aws-cdk/core';
 import { HttpUserPoolAuthorizer } from '../../lib';
@@ -112,7 +112,7 @@ describe('HttpUserPoolAuthorizer', () => {
   });
 });
 
-class DummyRouteIntegration implements IHttpRouteIntegration {
+class DummyRouteIntegration extends HttpRouteIntegration {
   public bind(_: HttpRouteIntegrationBindOptions) {
     return {
       payloadFormatVersion: PayloadFormatVersion.VERSION_2_0,

packages/@aws-cdk/aws-apigatewayv2-integrations/lib/http/http-proxy.ts

@@ -3,7 +3,7 @@ import {
   HttpRouteIntegrationBindOptions,
   HttpRouteIntegrationConfig,
   HttpMethod,
-  IHttpRouteIntegration,
+  HttpRouteIntegration,
   ParameterMapping,
   PayloadFormatVersion,
 } from '@aws-cdk/aws-apigatewayv2';
@@ -34,8 +34,9 @@ export interface HttpProxyIntegrationProps {
 /**
  * The HTTP Proxy integration resource for HTTP API
  */
-export class HttpProxyIntegration implements IHttpRouteIntegration {
+export class HttpProxyIntegration extends HttpRouteIntegration {
   constructor(private readonly props: HttpProxyIntegrationProps) {
+    super();
   }
 
   public bind(_: HttpRouteIntegrationBindOptions): HttpRouteIntegrationConfig {

packages/@aws-cdk/aws-apigatewayv2-integrations/lib/http/lambda.ts

@@ -2,7 +2,7 @@ import {
   HttpIntegrationType,
   HttpRouteIntegrationBindOptions,
   HttpRouteIntegrationConfig,
-  IHttpRouteIntegration,
+  HttpRouteIntegration,
   PayloadFormatVersion,
   ParameterMapping,
 } from '@aws-cdk/aws-apigatewayv2';
@@ -37,9 +37,10 @@ export interface LambdaProxyIntegrationProps {
 /**
  * The Lambda Proxy integration resource for HTTP API
  */
-export class LambdaProxyIntegration implements IHttpRouteIntegration {
+export class LambdaProxyIntegration extends HttpRouteIntegration {
 
   constructor(private readonly props: LambdaProxyIntegrationProps) {
+    super();
   }
 
   public bind(options: HttpRouteIntegrationBindOptions): HttpRouteIntegrationConfig {

packages/@aws-cdk/aws-apigatewayv2-integrations/lib/http/private/integration.ts

@@ -3,7 +3,7 @@ import {
   HttpIntegrationType,
   HttpRouteIntegrationBindOptions,
   HttpRouteIntegrationConfig,
-  IHttpRouteIntegration,
+  HttpRouteIntegration,
   PayloadFormatVersion,
   HttpMethod,
   IVpcLink,
@@ -37,7 +37,7 @@ export interface VpcLinkConfigurationOptions {
  *
  * @internal
  */
-export abstract class HttpPrivateIntegration implements IHttpRouteIntegration {
+export abstract class HttpPrivateIntegration extends HttpRouteIntegration {
   protected httpMethod = HttpMethod.ANY;
   protected payloadFormatVersion = PayloadFormatVersion.VERSION_1_0; // 1.0 is required and is the only supported format
   protected integrationType = HttpIntegrationType.HTTP_PROXY;

packages/@aws-cdk/aws-apigatewayv2-integrations/lib/websocket/lambda.ts

@@ -1,5 +1,5 @@
 import {
-  IWebSocketRouteIntegration,
+  WebSocketRouteIntegration,
   WebSocketIntegrationType,
   WebSocketRouteIntegrationBindOptions,
   WebSocketRouteIntegrationConfig,
@@ -21,8 +21,10 @@ export interface LambdaWebSocketIntegrationProps {
 /**
  * Lambda WebSocket Integration
  */
-export class LambdaWebSocketIntegration implements IWebSocketRouteIntegration {
-  constructor(private props: LambdaWebSocketIntegrationProps) {}
+export class LambdaWebSocketIntegration extends WebSocketRouteIntegration {
+  constructor(private props: LambdaWebSocketIntegrationProps) {
+    super();
+  }
 
   bind(options: WebSocketRouteIntegrationBindOptions): WebSocketRouteIntegrationConfig {
     const route = options.route;

packages/@aws-cdk/aws-apigatewayv2/lib/common/base.ts

@@ -1,6 +1,5 @@
 import * as cloudwatch from '@aws-cdk/aws-cloudwatch';
 import { Resource } from '@aws-cdk/core';
-import { IntegrationCache } from '../private/integration-cache';
 import { IApi } from './api';
 import { ApiMapping } from './api-mapping';
 import { DomainMappingOptions, IStage } from './stage';
@@ -12,10 +11,6 @@ import { DomainMappingOptions, IStage } from './stage';
 export abstract class ApiBase extends Resource implements IApi {
   abstract readonly apiId: string;
   abstract readonly apiEndpoint: string;
-  /**
-   * @internal
-   */
-  protected _integrationCache: IntegrationCache = new IntegrationCache();
 
   public metric(metricName: string, props?: cloudwatch.MetricOptions): cloudwatch.Metric {
     return new cloudwatch.Metric({

packages/@aws-cdk/aws-apigatewayv2/lib/http/api.ts

@@ -6,7 +6,7 @@ import { IApi } from '../common/api';
 import { ApiBase } from '../common/base';
 import { DomainMappingOptions } from '../common/stage';
 import { IHttpRouteAuthorizer } from './authorizer';
-import { IHttpRouteIntegration, HttpIntegration, HttpRouteIntegrationConfig } from './integration';
+import { HttpRouteIntegration } from './integration';
 import { BatchHttpRouteOptions, HttpMethod, HttpRoute, HttpRouteKey } from './route';
 import { IHttpStage, HttpStage, HttpStageOptions } from './stage';
 import { VpcLink, VpcLinkProps } from './vpc-link';
@@ -71,12 +71,6 @@ export interface IHttpApi extends IApi {
    * Add a new VpcLink
    */
   addVpcLink(options: VpcLinkProps): VpcLink
-
-  /**
-   * Add a http integration
-   * @internal
-   */
-  _addIntegration(scope: Construct, config: HttpRouteIntegrationConfig): HttpIntegration;
 }
 
 /**
@@ -99,7 +93,7 @@ export interface HttpApiProps {
    * An integration that will be configured on the catch-all route ($default).
    * @default - none
    */
-  readonly defaultIntegration?: IHttpRouteIntegration;
+  readonly defaultIntegration?: HttpRouteIntegration;
 
   /**
    * Whether a default stage and deployment should be automatically created.
@@ -286,31 +280,6 @@ abstract class HttpApiBase extends ApiBase implements IHttpApi { // note that th
 
     return vpcLink;
   }
-
-  /**
-   * @internal
-   */
-  public _addIntegration(scope: Construct, config: HttpRouteIntegrationConfig): HttpIntegration {
-    const { configHash, integration: existingIntegration } = this._integrationCache.getIntegration(scope, config);
-    if (existingIntegration) {
-      return existingIntegration as HttpIntegration;
-    }
-
-    const integration = new HttpIntegration(scope, `HttpIntegration-${configHash}`, {
-      httpApi: this,
-      integrationType: config.type,
-      integrationUri: config.uri,
-      method: config.method,
-      connectionId: config.connectionId,
-      connectionType: config.connectionType,
-      payloadFormatVersion: config.payloadFormatVersion,
-      secureServerName: config.secureServerName,
-      parameterMapping: config.parameterMapping,
-    });
-    this._integrationCache.saveIntegration(scope, config, integration);
-
-    return integration;
-  }
 }
 
 /**

packages/@aws-cdk/aws-apigatewayv2/lib/http/integration.ts

@@ -1,5 +1,6 @@
 /* eslint-disable quotes */
-import { Resource } from '@aws-cdk/core';
+import * as crypto from 'crypto';
+import { Resource, Stack } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 import { CfnIntegration } from '../apigatewayv2.generated';
 import { IIntegration } from '../common';
@@ -191,11 +192,46 @@ export interface HttpRouteIntegrationBindOptions {
 /**
  * The interface that various route integration classes will inherit.
  */
-export interface IHttpRouteIntegration {
+export abstract class HttpRouteIntegration {
+  private integration?: HttpIntegration;
+
+  /**
+   * Internal method called when binding this integration to the route.
+   * @internal
+   */
+  public _bindToRoute(options: HttpRouteIntegrationBindOptions): { readonly integrationId: string } {
+    if (this.integration && this.integration.httpApi.node.addr !== options.route.httpApi.node.addr) {
+      throw new Error('A single integration cannot be associated with multiple APIs.');
+    }
+
+    if (!this.integration) {
+      const config = this.bind(options);
+
+      this.integration = new HttpIntegration(options.scope, `HttpIntegration-${hash(config)}`, {
+        httpApi: options.route.httpApi,
+        integrationType: config.type,
+        integrationUri: config.uri,
+        method: config.method,
+        connectionId: config.connectionId,
+        connectionType: config.connectionType,
+        payloadFormatVersion: config.payloadFormatVersion,
+        secureServerName: config.secureServerName,
+        parameterMapping: config.parameterMapping,
+      });
+
+      function hash(x: any) {
+        const stringifiedConfig = JSON.stringify(Stack.of(options.scope).resolve(x));
+        const configHash = crypto.createHash('md5').update(stringifiedConfig).digest('hex');
+        return configHash;
+      }
+    }
+    return { integrationId: this.integration.integrationId };
+  }
+
   /**
    * Bind this integration to the route.
    */
-  bind(options: HttpRouteIntegrationBindOptions): HttpRouteIntegrationConfig;
+  public abstract bind(options: HttpRouteIntegrationBindOptions): HttpRouteIntegrationConfig;
 }
 
 /**

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

@@ -4,7 +4,7 @@ import { CfnRoute, CfnRouteProps } from '../apigatewayv2.generated';
 import { IRoute } from '../common';
 import { IHttpApi } from './api';
 import { IHttpRouteAuthorizer } from './authorizer';
-import { IHttpRouteIntegration } from './integration';
+import { HttpRouteIntegration } from './integration';
 
 /**
  * Represents a Route for an HTTP API.
@@ -88,7 +88,7 @@ export interface BatchHttpRouteOptions {
   /**
    * The integration to be configured on this route.
    */
-  readonly integration: IHttpRouteIntegration;
+  readonly integration: HttpRouteIntegration;
 }
 
 /**
@@ -149,13 +149,11 @@ export class HttpRoute extends Resource implements IHttpRoute {
     this.httpApi = props.httpApi;
     this.path = props.routeKey.path;
 
-    const config = props.integration.bind({
+    const config = props.integration._bindToRoute({
       route: this,
       scope: this,
     });
 
-    const integration = props.httpApi._addIntegration(this, config);
-
     const authBindResult = props.authorizer ? props.authorizer.bind({
       route: this,
       scope: this.httpApi instanceof Construct ? this.httpApi : this, // scope under the API if it's not imported
@@ -181,7 +179,7 @@ export class HttpRoute extends Resource implements IHttpRoute {
     const routeProps: CfnRouteProps = {
       apiId: props.httpApi.apiId,
       routeKey: props.routeKey.key,
-      target: `integrations/${integration.integrationId}`,
+      target: `integrations/${config.integrationId}`,
       authorizerId: authBindResult?.authorizerId,
       authorizationType: authBindResult?.authorizationType ?? 'NONE', // must be explicitly NONE (not undefined) for stack updates to work correctly
       authorizationScopes,

packages/@aws-cdk/aws-apigatewayv2/lib/private/integration-cache.ts

@@ -4,18 +4,12 @@ import { Construct } from 'constructs';
 import { CfnApi } from '../apigatewayv2.generated';
 import { IApi } from '../common/api';
 import { ApiBase } from '../common/base';
-import { WebSocketRouteIntegrationConfig, WebSocketIntegration } from './integration';
 import { WebSocketRoute, WebSocketRouteOptions } from './route';
 
 /**
  * Represents a WebSocket API
  */
 export interface IWebSocketApi extends IApi {
-  /**
-   * Add a websocket integration
-   * @internal
-   */
-  _addIntegration(scope: Construct, config: WebSocketRouteIntegrationConfig): WebSocketIntegration
 }
 
 /**
@@ -100,25 +94,6 @@ export class WebSocketApi extends ApiBase implements IWebSocketApi {
     }
   }
 
-  /**
-   * @internal
-   */
-  public _addIntegration(scope: Construct, config: WebSocketRouteIntegrationConfig): WebSocketIntegration {
-    const { configHash, integration: existingIntegration } = this._integrationCache.getIntegration(scope, config);
-    if (existingIntegration) {
-      return existingIntegration as WebSocketIntegration;
-    }
-
-    const integration = new WebSocketIntegration(scope, `WebSocketIntegration-${configHash}`, {
-      webSocketApi: this,
-      integrationType: config.type,
-      integrationUri: config.uri,
-    });
-    this._integrationCache.saveIntegration(scope, config, integration);
-
-    return integration;
-  }
-
   /**
    * Add a new route
    */

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

@@ -1,4 +1,5 @@
-import { Resource } from '@aws-cdk/core';
+import * as crypto from 'crypto';
+import { Resource, Stack } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 import { CfnIntegration } from '../apigatewayv2.generated';
 import { IIntegration } from '../common';
@@ -87,11 +88,41 @@ export interface WebSocketRouteIntegrationBindOptions {
 /**
  * The interface that various route integration classes will inherit.
  */
-export interface IWebSocketRouteIntegration {
+export abstract class WebSocketRouteIntegration {
+  private integration?: WebSocketIntegration;
+
+  /**
+   * Internal method called when binding this integration to the route.
+   * @internal
+   */
+  public _bindToRoute(options: WebSocketRouteIntegrationBindOptions): { readonly integrationId: string } {
+    if (this.integration && this.integration.webSocketApi.node.addr !== options.route.webSocketApi.node.addr) {
+      throw new Error('A single integration cannot be associated with multiple APIs.');
+    }
+
+    if (!this.integration) {
+      const config = this.bind(options);
+
+      this.integration = new WebSocketIntegration(options.scope, `WebSocketIntegration-${hash(config)}`, {
+        webSocketApi: options.route.webSocketApi,
+        integrationType: config.type,
+        integrationUri: config.uri,
+      });
+
+      function hash(x: any) {
+        const stringifiedConfig = JSON.stringify(Stack.of(options.scope).resolve(x));
+        const configHash = crypto.createHash('md5').update(stringifiedConfig).digest('hex');
+        return configHash;
+      }
+    }
+
+    return { integrationId: this.integration.integrationId };
+  }
+
   /**
    * Bind this integration to the route.
    */
-  bind(options: WebSocketRouteIntegrationBindOptions): WebSocketRouteIntegrationConfig;
+  public abstract bind(options: WebSocketRouteIntegrationBindOptions): WebSocketRouteIntegrationConfig;
 }
 
 /**

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

@@ -3,7 +3,7 @@ import { Construct } from 'constructs';
 import { CfnRoute } from '../apigatewayv2.generated';
 import { IRoute } from '../common';
 import { IWebSocketApi } from './api';
-import { IWebSocketRouteIntegration } from './integration';
+import { WebSocketRouteIntegration } from './integration';
 
 /**
  * Represents a Route for an WebSocket API.
@@ -28,7 +28,7 @@ export interface WebSocketRouteOptions {
   /**
    * The integration to be configured on this route.
    */
-  readonly integration: IWebSocketRouteIntegration;
+  readonly integration: WebSocketRouteIntegration;
 }
 
 
@@ -67,17 +67,15 @@ export class WebSocketRoute extends Resource implements IWebSocketRoute {
     this.webSocketApi = props.webSocketApi;
     this.routeKey = props.routeKey;
 
-    const config = props.integration.bind({
+    const config = props.integration._bindToRoute({
       route: this,
       scope: this,
     });
 
-    const integration = props.webSocketApi._addIntegration(this, config);
-
     const route = new CfnRoute(this, 'Resource', {
       apiId: props.webSocketApi.apiId,
       routeKey: props.routeKey,
-      target: `integrations/${integration.integrationId}`,
+      target: `integrations/${config.integrationId}`,
     });
     this.routeId = route.ref;
   }

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

@@ -6,7 +6,7 @@ import { Duration, Stack } from '@aws-cdk/core';
 import {
   CorsHttpMethod, DomainName,
   HttpApi, HttpAuthorizer, HttpIntegrationType, HttpMethod, HttpRouteAuthorizerBindOptions, HttpRouteAuthorizerConfig,
-  HttpRouteIntegrationBindOptions, HttpRouteIntegrationConfig, IHttpRouteAuthorizer, IHttpRouteIntegration, HttpNoneAuthorizer, PayloadFormatVersion,
+  HttpRouteIntegrationBindOptions, HttpRouteIntegrationConfig, IHttpRouteAuthorizer, HttpRouteIntegration, HttpNoneAuthorizer, PayloadFormatVersion,
 } from '../../lib';
 
 describe('HttpApi', () => {
@@ -531,7 +531,7 @@ describe('HttpApi', () => {
   });
 });
 
-class DummyRouteIntegration implements IHttpRouteIntegration {
+class DummyRouteIntegration extends HttpRouteIntegration {
   public bind(_: HttpRouteIntegrationBindOptions): HttpRouteIntegrationConfig {
     return {
       payloadFormatVersion: PayloadFormatVersion.VERSION_2_0,

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

@@ -2,7 +2,7 @@ import { Template } from '@aws-cdk/assertions';
 import { Stack, App } from '@aws-cdk/core';
 import {
   HttpApi, HttpAuthorizer, HttpAuthorizerType, HttpConnectionType, HttpIntegrationType, HttpMethod, HttpRoute,
-  HttpRouteAuthorizerBindOptions, HttpRouteAuthorizerConfig, HttpRouteIntegrationConfig, HttpRouteKey, IHttpRouteAuthorizer, IHttpRouteIntegration,
+  HttpRouteAuthorizerBindOptions, HttpRouteAuthorizerConfig, HttpRouteIntegrationConfig, HttpRouteKey, IHttpRouteAuthorizer, HttpRouteIntegration,
   MappingValue,
   ParameterMapping,
   PayloadFormatVersion,
@@ -81,42 +81,42 @@ describe('HttpRoute', () => {
     Template.fromStack(stack).resourceCountIs('AWS::ApiGatewayV2::Integration', 1);
   });
 
-  test('integration can be used across HttpApis', () => {
+  test('integration cannot be used across HttpApis', () => {
     // GIVEN
     const integration = new DummyIntegration();
 
     // WHEN
-    const stack1 = new Stack();
-    const httpApi1 = new HttpApi(stack1, 'HttpApi1');
+    const stack = new Stack();
+    const httpApi1 = new HttpApi(stack, 'HttpApi1');
+    const httpApi2 = new HttpApi(stack, 'HttpApi2');
 
-    new HttpRoute(stack1, 'HttpRoute1', {
+    new HttpRoute(stack, 'HttpRoute1', {
       httpApi: httpApi1,
       integration,
       routeKey: HttpRouteKey.with('/books', HttpMethod.GET),
     });
-    new HttpRoute(stack1, 'HttpRoute2', {
-      httpApi: httpApi1,
-      integration,
-      routeKey: HttpRouteKey.with('/books', HttpMethod.POST),
-    });
-
-    const stack2 = new Stack();
-    const httpApi2 = new HttpApi(stack2, 'HttpApi2');
 
-    new HttpRoute(stack2, 'HttpRoute1', {
+    expect(() => new HttpRoute(stack, 'HttpRoute2', {
       httpApi: httpApi2,
       integration,
       routeKey: HttpRouteKey.with('/books', HttpMethod.GET),
+    })).toThrow(/cannot be associated with multiple APIs/);
+  });
+
+  test('associating integrations in different APIs creates separate AWS::ApiGatewayV2::Integration', () => {
+    const stack = new Stack();
+
+    const api = new HttpApi(stack, 'HttpApi');
+    api.addRoutes({
+      path: '/books',
+      integration: new DummyIntegration(),
     });
-    new HttpRoute(stack2, 'HttpRoute2', {
-      httpApi: httpApi2,
-      integration,
-      routeKey: HttpRouteKey.with('/books', HttpMethod.POST),
+    api.addRoutes({
+      path: '/magazines',
+      integration: new DummyIntegration(),
     });
 
-    // THEN
-    Template.fromStack(stack1).resourceCountIs('AWS::ApiGatewayV2::Integration', 1);
-    Template.fromStack(stack2).resourceCountIs('AWS::ApiGatewayV2::Integration', 1);
+    Template.fromStack(stack).hasResource('AWS::ApiGatewayV2::Integration', 2);
   });
 
   test('route defined in a separate stack does not create cycles', () => {
@@ -167,7 +167,7 @@ describe('HttpRoute', () => {
     const stack = new Stack();
     const httpApi = new HttpApi(stack, 'HttpApi');
 
-    class PrivateIntegration implements IHttpRouteIntegration {
+    class PrivateIntegration extends HttpRouteIntegration {
       public bind(): HttpRouteIntegrationConfig {
         return {
           method: HttpMethod.ANY,
@@ -212,7 +212,7 @@ describe('HttpRoute', () => {
     const stack = new Stack();
     const httpApi = new HttpApi(stack, 'HttpApi');
 
-    class PrivateIntegration implements IHttpRouteIntegration {
+    class PrivateIntegration extends HttpRouteIntegration {
       public bind(): HttpRouteIntegrationConfig {
         return {
           method: HttpMethod.ANY,
@@ -310,7 +310,7 @@ describe('HttpRoute', () => {
   });
 });
 
-class DummyIntegration implements IHttpRouteIntegration {
+class DummyIntegration extends HttpRouteIntegration {
   public bind(): HttpRouteIntegrationConfig {
     return {
       type: HttpIntegrationType.HTTP_PROXY,

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

@@ -2,7 +2,7 @@ import { Match, Template } from '@aws-cdk/assertions';
 import { User } from '@aws-cdk/aws-iam';
 import { Stack } from '@aws-cdk/core';
 import {
-  IWebSocketRouteIntegration, WebSocketApi, WebSocketIntegrationType,
+  WebSocketRouteIntegration, WebSocketApi, WebSocketIntegrationType,
   WebSocketRouteIntegrationBindOptions, WebSocketRouteIntegrationConfig,
 } from '../../lib';
 
@@ -126,7 +126,7 @@ describe('WebSocketApi', () => {
   });
 });
 
-class DummyIntegration implements IWebSocketRouteIntegration {
+class DummyIntegration extends WebSocketRouteIntegration {
   bind(_options: WebSocketRouteIntegrationBindOptions): WebSocketRouteIntegrationConfig {
     return {
       type: WebSocketIntegrationType.AWS_PROXY,

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

@@ -1,7 +1,7 @@
 import { Template } from '@aws-cdk/assertions';
 import { Stack } from '@aws-cdk/core';
 import {
-  IWebSocketRouteIntegration, WebSocketApi, WebSocketIntegrationType,
+  WebSocketRouteIntegration, WebSocketApi, WebSocketIntegrationType,
   WebSocketRoute, WebSocketRouteIntegrationBindOptions, WebSocketRouteIntegrationConfig,
 } from '../../lib';
 
@@ -41,10 +41,50 @@ describe('WebSocketRoute', () => {
       IntegrationUri: 'some-uri',
     });
   });
+
+  test('integration cannot be used across WebSocketApis', () => {
+    // GIVEN
+    const integration = new DummyIntegration();
+
+    // WHEN
+    const stack = new Stack();
+    const webSocketApi1 = new WebSocketApi(stack, 'WebSocketApi1');
+    const webSocketApi2 = new WebSocketApi(stack, 'WebSocketApi2');
+
+    new WebSocketRoute(stack, 'WebSocketRoute1', {
+      webSocketApi: webSocketApi1,
+      integration,
+      routeKey: 'route',
+    });
+
+    expect(() => new WebSocketRoute(stack, 'WebSocketRoute2', {
+      webSocketApi: webSocketApi2,
+      integration,
+      routeKey: 'route',
+    })).toThrow(/cannot be associated with multiple APIs/);
+  });
+
+  test('associating integrations in different APIs creates separate AWS::ApiGatewayV2::Integration', () => {
+    const stack = new Stack();
+
+    const api = new WebSocketApi(stack, 'WebSocketApi');
+    new WebSocketRoute(stack, 'WebSocketRoute1', {
+      webSocketApi: api,
+      integration: new DummyIntegration(),
+      routeKey: '/books',
+    });
+    new WebSocketRoute(stack, 'WebSocketRoute2', {
+      webSocketApi: api,
+      integration: new DummyIntegration(),
+      routeKey: '/magazines',
+    });
+
+    Template.fromStack(stack).hasResource('AWS::ApiGatewayV2::Integration', 2);
+  });
 });
 
 
-class DummyIntegration implements IWebSocketRouteIntegration {
+class DummyIntegration extends WebSocketRouteIntegration {
   bind(_options: WebSocketRouteIntegrationBindOptions): WebSocketRouteIntegrationConfig {
     return {
       type: WebSocketIntegrationType.AWS_PROXY,