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Saqib Dhuka
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StepFunctionsRestApi implemented along with unit and integration testing.
Fixed Integration test and generated expected json for stepFunctionsRestApi Stack deployment. Added code snippet to the README. Removing restApiprops option as the composition in StepFunctionsRestApiProps. closes #15081.
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‎packages/@aws-cdk/aws-apigateway/README.md‎

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@@ -22,6 +22,7 @@ running on AWS Lambda, or any web application.
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- [Defining APIs](#defining-apis)
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- [Breaking up Methods and Resources across Stacks](#breaking-up-methods-and-resources-across-stacks)
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- [AWS Lambda-backed APIs](#aws-lambda-backed-apis)
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- [AWS Synchronous State Machine backed APIs](#aws-synchronous-state-machine-backed-APIs)
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- [Integration Targets](#integration-targets)
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- [Usage Plan & API Keys](#usage-plan--api-keys)
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- [Working with models](#working-with-models)
@@ -106,6 +107,19 @@ item.addMethod('GET'); // GET /items/{item}
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item.addMethod('DELETE', new apigateway.HttpIntegration('http://amazon.com'));
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```
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## AWS Synchronous State Machine backed APIs
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You can use Amazon API Gateway with AWS Synchronous Express State Machine as the backend integration. The `StepFunctionsRestApi` construct makes this easy and also sets up input, output and error mapping.
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The following code defines a REST API that routes all requests to the specified AWS Synchronous Express State Machine:
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```ts
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declare const stateMachine: stepFunctions.StateMachine;
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new apigateway.StepFunctionsRestApi(this, 'StepFunctions-rest-api', {
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handler: stateMachine,
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});
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```
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### Breaking up Methods and Resources across Stacks
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It is fairly common for REST APIs with a large number of Resources and Methods to hit the [CloudFormation

‎packages/@aws-cdk/aws-apigateway/lib/index.ts‎

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@@ -21,6 +21,7 @@ export * from './authorizers';
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export * from './access-log';
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export * from './api-definition';
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export * from './gateway-response';
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export * from './stepFunctions-api';
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// AWS::ApiGateway CloudFormation Resources:
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export * from './apigateway.generated';

‎packages/@aws-cdk/aws-apigateway/lib/integrations/index.ts‎

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@@ -2,3 +2,4 @@ export * from './aws';
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export * from './lambda';
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export * from './http';
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export * from './mock';
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export * from './stepFunctions';

‎packages/@aws-cdk/aws-apigateway/lib/integrations/stepFunctions.ts‎

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import * as iam from '@aws-cdk/aws-iam';
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import * as sfn from '@aws-cdk/aws-stepfunctions';
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import { Token } from '@aws-cdk/core';
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import { IntegrationConfig, IntegrationOptions, PassthroughBehavior } from '../integration';
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import { Method } from '../method';
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import { AwsIntegration } from './aws';
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/**
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* StepFunctionsIntegrationOptions
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*/
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export interface StepFunctionsIntegrationOptions extends IntegrationOptions {
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/**
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* Use proxy integration or normal (request/response mapping) integration.
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*
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* @default false
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*/
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readonly proxy?: boolean;
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/**
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* Check if cors is enabled
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* @default false
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*/
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readonly corsEnabled?: boolean;
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}
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/**
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* Integrates a Synchronous Express State Machine from AWS Step Functions to an API Gateway method.
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*
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* @example
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*
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* const handler = new sfn.StateMachine(this, 'MyStateMachine', ...);
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* api.addMethod('GET', new StepFunctionsIntegration(handler));
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*
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*/
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export class StepFunctionsIntegration extends AwsIntegration {
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private readonly handler: sfn.IStateMachine;
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constructor(handler: sfn.IStateMachine, options: StepFunctionsIntegrationOptions = { }) {
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const integResponse = getIntegrationResponse();
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const requestTemplate = getRequestTemplates(handler);
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if (options.corsEnabled) {
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super({
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proxy: options.proxy,
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service: 'states',
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action: 'StartSyncExecution',
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options,
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});
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} else {
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super({
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proxy: options.proxy,
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service: 'states',
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action: 'StartSyncExecution',
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options: {
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credentialsRole: options.credentialsRole,
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integrationResponses: integResponse,
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passthroughBehavior: PassthroughBehavior.NEVER,
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requestTemplates: requestTemplate,
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},
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});
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}
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this.handler = handler;
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}
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public bind(method: Method): IntegrationConfig {
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const bindResult = super.bind(method);
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const principal = new iam.ServicePrincipal('apigateway.amazonaws.com');
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this.handler.grantExecution(principal, 'states:StartSyncExecution');
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let stateMachineName;
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if (this.handler instanceof sfn.StateMachine) {
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//if not imported, extract the name from the CFN layer to reach the
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//literal value if it is given (rather than a token)
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stateMachineName = (this.handler.node.defaultChild as sfn.CfnStateMachine).stateMachineName;
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} else {
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stateMachineName = 'StateMachine-' + (String(this.handler.stack.node.addr).substring(0, 8));
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}
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let deploymentToken;
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if (!Token.isUnresolved(stateMachineName)) {
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deploymentToken = JSON.stringify({ stateMachineName });
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}
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return {
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...bindResult,
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deploymentToken,
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};
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}
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}
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function getIntegrationResponse() {
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const errorResponse = [
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{
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selectionPattern: '4\\d{2}',
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statusCode: '400',
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responseTemplates: {
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'application/json': `{
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"error": "Bad input!"
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}`,
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},
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},
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{
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selectionPattern: '5\\d{2}',
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statusCode: '500',
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responseTemplates: {
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'application/json': '"error": $input.path(\'$.error\')',
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},
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},
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];
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const integResponse = [
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{
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statusCode: '200',
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responseTemplates: {
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'application/json': `#set($inputRoot = $input.path('$'))
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#if($input.path('$.status').toString().equals("FAILED"))
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#set($context.responseOverride.status = 500)
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{
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"error": "$input.path('$.error')",
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"cause": "$input.path('$.cause')"
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}
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#else
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$input.path('$.output')
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#end`,
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},
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},
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...errorResponse,
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];
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return integResponse;
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}
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function getRequestTemplates(handler: sfn.IStateMachine) {
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const templateString = getTemplateString(handler);
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const requestTemplate: { [contentType:string] : string } =
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{
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'application/json': templateString,
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};
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return requestTemplate;
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}
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function getTemplateString(handler: sfn.IStateMachine): string {
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const templateString: string = `
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#set($inputRoot = $input.path('$')) {
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"input": "$util.escapeJavaScript($input.json(\'$\'))",
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"stateMachineArn": "${handler.stateMachineArn}"
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}`;
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return templateString;
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}

‎packages/@aws-cdk/aws-apigateway/lib/stepFunctions-api.ts‎

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import * as iam from '@aws-cdk/aws-iam';
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import * as sfn from '@aws-cdk/aws-stepfunctions';
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import { Construct } from 'constructs';
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import { RestApi, RestApiProps } from '.';
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import { StepFunctionsIntegration } from './integrations/stepFunctions';
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import { Model } from './model';
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/**
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* StepFunctionsRestApiProps
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*/
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export interface StepFunctionsRestApiProps extends RestApiProps {
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/**
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* The default State Machine that handles all requests from this API.
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*
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* This handler will be used as a the default integration for all methods in
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* this API, unless specified otherwise in `addMethod`.
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*/
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readonly handler: sfn.IStateMachine;
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/**
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* If true, route all requests to the State Machine
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*
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* If set to false, you will need to explicitly define the API model using
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* `addResource` and `addMethod` (or `addProxy`).
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*
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* @default true
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*/
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readonly proxy?: boolean;
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}
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/**
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* Defines an API Gateway REST API with a Synchrounous Express State Machine as a proxy integration.
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*
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*/
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export class StepFunctionsRestApi extends RestApi {
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constructor(scope: Construct, id: string, props: StepFunctionsRestApiProps) {
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if (props.defaultIntegration) {
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throw new Error('Cannot specify "defaultIntegration" since Step Functions integration is automatically defined');
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}
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const apiRole = getRole(scope, props);
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const methodResp = getMethodResponse();
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let corsEnabled;
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if (props.defaultCorsPreflightOptions !== undefined) {
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corsEnabled = true;
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} else {
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corsEnabled = false;
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}
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super(scope, id, {
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defaultIntegration: new StepFunctionsIntegration(props.handler, {
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credentialsRole: apiRole,
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proxy: false, //proxy not avaialble for Step Functions yet
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corsEnabled: corsEnabled,
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}),
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...props,
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});
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this.root.addMethod('ANY', new StepFunctionsIntegration(props.handler, {
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credentialsRole: apiRole,
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}), {
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methodResponses: [
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...methodResp,
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],
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});
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}
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}
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function getRole(scope: Construct, props: StepFunctionsRestApiProps): iam.Role {
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const apiName: string = props.handler + '-apiRole';
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const apiRole = new iam.Role(scope, apiName, {
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assumedBy: new iam.ServicePrincipal('apigateway.amazonaws.com'),
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});
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apiRole.attachInlinePolicy(
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new iam.Policy(scope, 'AllowStartSyncExecution', {
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statements: [
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new iam.PolicyStatement({
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actions: ['states:StartSyncExecution'],
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effect: iam.Effect.ALLOW,
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resources: [props.handler.stateMachineArn],
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}),
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],
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}),
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);
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return apiRole;
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}
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function getMethodResponse() {
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const methodResp = [
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{
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statusCode: '200',
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responseModels: {
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'application/json': Model.EMPTY_MODEL,
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},
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},
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{
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statusCode: '400',
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responseModels: {
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'application/json': Model.ERROR_MODEL,
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},
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},
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{
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statusCode: '500',
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responseModels: {
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'application/json': Model.ERROR_MODEL,
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},
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},
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];
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return methodResp;
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}

‎packages/@aws-cdk/aws-apigateway/package.json‎

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"@aws-cdk/aws-s3-assets": "0.0.0",
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"@aws-cdk/core": "0.0.0",
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"@aws-cdk/cx-api": "0.0.0",
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"constructs": "^3.3.69"
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"constructs": "^3.3.69",
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"@aws-cdk/aws-stepfunctions": "0.0.0"
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},
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"homepage": "https://github.com/aws/aws-cdk",
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"peerDependencies": {
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"@aws-cdk/aws-s3-assets": "0.0.0",
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"@aws-cdk/core": "0.0.0",
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"@aws-cdk/cx-api": "0.0.0",
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"constructs": "^3.3.69"
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"constructs": "^3.3.69",
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"@aws-cdk/aws-stepfunctions": "0.0.0"
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},
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"engines": {
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"node": ">= 10.13.0 <13 || >=13.7.0"
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"attribute-tag:@aws-cdk/aws-apigateway.RequestAuthorizer.authorizerArn",
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"attribute-tag:@aws-cdk/aws-apigateway.TokenAuthorizer.authorizerArn",
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"attribute-tag:@aws-cdk/aws-apigateway.RestApi.restApiName",
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"attribute-tag:@aws-cdk/aws-apigateway.StepFunctionsRestApi.restApiName",
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"attribute-tag:@aws-cdk/aws-apigateway.SpecRestApi.restApiName",
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"attribute-tag:@aws-cdk/aws-apigateway.LambdaRestApi.restApiName",
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"from-method:@aws-cdk/aws-apigateway.Stage",

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