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In this chapter we will define a new construct called HitCounter. This construct can be attached to any Lambda function that’s used as an API Gateway backend, and it will count how many requests were issued to each URL path. It will store this in a DynamoDB table. See Also Writing Constructs in the AWS CDK User Guide

Add a LambdaRestApi construct to your stack Going back to lib/cdk-workshop-stack.ts, let’s define an API endpoint and associate it with our Lambda function: import * as cdk from 'aws-cdk-lib'; import * as lambda from 'aws-cdk-lib/aws-lambda'; import * as apigw from 'aws-cdk-lib/aws-apigateway'; export class CdkWorkshopStack extends cdk.Stack { constructor(scope: cdk.App, id: string, props?: cdk...

Faster personal deployments This section is not necessary to complete the workshop, but we recommend that you take the time to see how cdk deploy --hotswap and cdk watch can speed up your personal deployments. It’s great that we have a working lambda! But what if we want to tweak the lambda code to get it just right? Let’s say that we have now decided that we want our lambda function to respond ..

Lambda handler code We’ll start with the AWS Lambda handler code. Create a directory lambda in the root of your project tree (next to bin and lib). Add a file called lambda/hello.js with the following contents: exports.handler = async function(event) { console.log("request:", JSON.stringify(event, undefined, 2)); return { statusCode: 200, headers: { "Content-Type": "text/plain" }, body: `Hello, ..

Okay, we’ve got a CloudFormation template. What’s next? Let’s deploy it into our account! Bootstrapping an environment The first time you deploy an AWS CDK app into an environment (account/region), you can install a “bootstrap stack”. This stack includes resources that are used in the toolkit’s operation. For example, the stack includes an S3 bucket that is used to store templates and assets dur..

Synthesize a template from your app AWS CDK apps are effectively only a definition of your infrastructure using code. When CDK apps are executed, they produce (or “synthesize”, in CDK parlance) an AWS CloudFormation template for each stack defined in your application. To synthesize a CDK app, use the cdk synth command. Let’s check out the template synthesized from the sample app: The CDK CLI req..

Explore your project directory You’ll see something like this: lib/cdk-workshop-stack.ts is where your CDK application’s main stack is defined. This is the file we’ll be spending most of our time in. bin/cdk-workshop.ts is the entrypoint of the CDK application. It will load the stack defined in lib/cdk-workshop-stack.ts. package.json is your npm module manifest. It includes information like the ..

Compiling your TypeScript code Since TypeScript sources need to be compiled to JavaScript, every time we make a modification to our source files, we would want them to be compiled to .js. This is an important step. Make sure you leave the “watch” terminal session open at the end of this step. Your project is already configured with a nice little npm script called watch. Open new terminal window ..

Create project directory Create an empty directory on your system: mkdir cdk-workshop && cd cdk-workshop cdk init We will use cdk init to create a new TypeScript CDK project: cdk init sample-app --language typescript Output should look like this (you can safely ignore warnings about initialization of a git repository, this probably means you don’t have git installed, which is fine for this works..

Async and Promises Async Do others while it’s working Do things that take long time (json from web service) Synchronous Block execution of work MIxing Synchronous and Asynchronous Possible Problems Know when synchronous and how to handle it (callbacks) callBack function (one problem) Another callback. (old ways) Possible Solutions callBack function (old ways) Another callback. Promises (better o..