feat(newex): example of Cognito-protected APIGateway backed by Lambda

typescript/cognito-api-lambda/README.md

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+# APIGateway backed by Lambda and protected by Cognito User Pools.
+<!--BEGIN STABILITY BANNER-->
+---
+
+![Stability: Stable](https://img.shields.io/badge/stability-Stable-success.svg?style=for-the-badge)
+
+> **This is a stable example. It should successfully build out of the box**
+>
+> This examples does is built on Construct Libraries marked "Stable" and does not have any infrastructure prerequisites to build.
+
+---
+<!--END STABILITY BANNER-->
+
+This an example of an APIGateway that is protected with a Cognito User Pool, pointing to a Hello World Lambda.
+
+## Build
+
+To build this app, you need to be in this example's root folder. Then run the following:
+
+```bash
+npm install -g aws-cdk
+npm install
+npm run build
+```
+
+This will install the necessary CDK, then this example's dependencies, and then build your TypeScript files and your CloudFormation template.
+
+## Deploy
+
+Run `cdk deploy`. This will deploy / redeploy your Stack to your AWS Account.
+
+After the deployment you will see the API's URL, which represents the url you can then use.
+
+## The Component Structure
+
+The whole component contains:
+
+- A Lambda Function that returns "Hello world!".
+- An API with GET method that points to this Function.
+- A Cognito User Pool
+- An Authorizer for the API with the User Pool attached.
+
+## CDK Toolkit
+
+The [`cdk.json`](./cdk.json) file in the root of this repository includes
+instructions for the CDK toolkit on how to execute this program.
+
+After building your TypeScript code, you will be able to run the CDK toolkits commands as usual:
+
+    $ cdk ls
+    <list all stacks in this program>
+
+    $ cdk synth
+    <generates and outputs cloudformation template>
+
+    $ cdk deploy
+    <deploys stack to your account>
+
+    $ cdk diff
+    <shows diff against deployed stack>

typescript/cognito-api-lambda/cdk.json

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+{
+    "app": "node index"
+}

typescript/cognito-api-lambda/index.ts

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+import { LambdaRestApi, CfnAuthorizer, LambdaIntegration, AuthorizationType } from '@aws-cdk/aws-apigateway';
+import { AssetCode, Function, Runtime } from '@aws-cdk/aws-lambda';
+import { App, Stack } from '@aws-cdk/core';
+import { UserPool, SignInType } from '@aws-cdk/aws-cognito'
+
+export class CognitoProtectedApi extends Stack {
+  constructor(app: App, id: string) {
+    super(app, id);
+
+    // Function that returns 201 with "Hello world!"
+    const helloWorldFunction = new Function(this, 'helloWorldFunction', {
+      code: new AssetCode('src'),
+      handler: 'helloworld.handler',
+      runtime: Runtime.NODEJS_12_X
+    });
+
+    // Rest API backed by the helloWorldFunction
+    const helloWorldLambdaRestApi = new LambdaRestApi(this, 'helloWorldLambdaRestApi', {
+      restApiName: 'Hello World API',
+      handler: helloWorldFunction,
+      proxy: false,
+    });
+
+    // Cognito User Pool with Email Sign-in Type.
+    const userPool = new UserPool(this, 'userPool', {
+      signInType: SignInType.EMAIL
+    })
+
+    // Authorizer for the Hello World API that uses the
+    // Cognito User pool to Authorize users.
+    const authorizer = new CfnAuthorizer(this, 'cfnAuth', {
+      restApiId: helloWorldLambdaRestApi.restApiId,
+      name: 'HelloWorldAPIAuthorizer',
+      type: 'COGNITO_USER_POOLS',
+      identitySource: 'method.request.header.Authorization',
+      providerArns: [userPool.userPoolArn],
+    })
+
+    // Hello Resource API for the REST API. 
+    const hello = helloWorldLambdaRestApi.root.addResource('HELLO');
+
+    // GET method for the HELLO API resource. It uses Cognito for
+    // authorization and the auathorizer defined above.
+    hello.addMethod('GET', new LambdaIntegration(helloWorldFunction), {
+      authorizationType: AuthorizationType.COGNITO,
+      authorizer: {
+        authorizerId: authorizer.ref
+      }
+
+    })
+
+  }
+}
+
+
+const app = new App();
+new CognitoProtectedApi(app, 'CognitoProtectedApi');
+app.synth();

typescript/cognito-api-lambda/package.json

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+{
+  "name": "cognito-api-lambda",
+  "version": "1.0.0",
+  "description": "Running an API Gateway using Cognito User Pool as an Authorizer for Hello World Lambda",
+  "private": true,
+  "scripts": {
+    "build": "tsc",
+    "watch": "tsc -w",
+    "cdk": "cdk"
+  },
+  "author": {
+    "name": "Campion Fellin <[email protected]>"
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "@types/node": "^10.17.0",
+    "typescript": "~3.7.2"
+  },
+  "dependencies": {
+    "@aws-cdk/aws-apigateway": "*",
+    "@aws-cdk/aws-cognito": "*",
+    "@aws-cdk/aws-dynamodb": "*",
+    "@aws-cdk/aws-lambda": "*",
+    "@aws-cdk/core": "*"
+  }
+}

typescript/cognito-api-lambda/src/helloworld.ts

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+// Pretty basic Hello World lambda...
+
+export const handler = async (event: any = {}) : Promise <any> => {
+  console.log(event);
+
+  return { statusCode: 201, body: 'Hello world!' };
+};

typescript/cognito-api-lambda/tsconfig.json

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+{
+    "compilerOptions": {
+        "target":"ES2018",
+        "module": "commonjs",
+        "lib": ["es2016", "es2017.object", "es2017.string"],
+        "strict": true,
+        "noImplicitAny": true,
+        "strictNullChecks": true,
+        "noImplicitThis": true,
+        "alwaysStrict": true,
+        "noUnusedLocals": true,
+        "noUnusedParameters": true,
+        "noImplicitReturns": true,
+        "noFallthroughCasesInSwitch": false,
+        "inlineSourceMap": true,
+        "inlineSources": true,
+        "experimentalDecorators": true,
+        "strictPropertyInitialization":false
+    }
+}
+