Deploy a Serverless API with AWS CDK and AWS Lambda

You can find the project source code on GitHub.

In this tutorial, we will implement a Serverless API using AWS Lambda and we will deploy it using AWS CDK. We will use Typescript as the CDK language. It will be a view counter where we keep the state in Redis.

What is AWS CDK?#

AWS CDK is an interesting project which allows you to provision and deploy AWS infrastructure with code. Currently TypeScript, JavaScript, Python, Java, C#/.Net and Go are supported. You can compare AWS CDK with following technologies:

AWS CloudFormation
AWS SAM
Serverless Framework

The above projects allows you to set up the infrastructure with configuration files (yaml, json) while with AWS CDK, you set up the resources with code. For more information about CDK see the related AWS Docs.

Prerequisites#

Complete all steps in Getting started with the AWS CDK

Project Setup#

Create and navigate to a directory named counter-cdk. The CDK CLI uses this directory name to name things in your CDK code, so if you decide to use a different name, don't forget to make the appropriate changes when applying this tutorial.

mkdir counter-cdk && cd counter-cdk

Initialize a new CDK project.

cdk init app --language typescript

Install @upstash/redis.

npm install @upstash/redis

Counter Function Setup#

Create /api/counter.ts.

/api/counter.ts

import { Redis } from '@upstash/redis';const redis = Redis.fromEnv();export const handler = async function() {    const count = await redis.incr("counter");    return {        statusCode: 200,        body: JSON.stringify('Counter: ' + count),    };};

Counter Stack Setup#

Update /lib/counter-cdk-stack.ts.

/lib/counter-cdk-stack.ts

import * as cdk from 'aws-cdk-lib';import { Construct } from 'constructs';import * as lambda from 'aws-cdk-lib/aws-lambda';import * as nodejs from 'aws-cdk-lib/aws-lambda-nodejs';export class CounterCdkStack extends cdk.Stack {  constructor(scope: Construct, id: string, props?: cdk.StackProps) {    super(scope, id, props);    const counterFunction = new nodejs.NodejsFunction(this, 'CounterFunction', {      entry: 'api/counter.ts',      handler: 'handler',      runtime: lambda.Runtime.NODEJS_20_X,      environment: {        UPSTASH_REDIS_REST_URL: process.env.UPSTASH_REDIS_REST_URL || '',        UPSTASH_REDIS_REST_TOKEN: process.env.UPSTASH_REDIS_REST_TOKEN || '',      },      bundling: {        format: nodejs.OutputFormat.ESM,        target: "node20",        nodeModules: ['@upstash/redis'],      },    });    const counterFunctionUrl = counterFunction.addFunctionUrl({      authType: lambda.FunctionUrlAuthType.NONE,    });    new cdk.CfnOutput(this, "counterFunctionUrlOutput", {      value: counterFunctionUrl.url,    })  }}

Database Setup#

Create a Redis database using Upstash Console or Upstash CLI and export UPSTASH_REDIS_REST_URL and UPSTASH_REDIS_REST_TOKEN to your environment.

export UPSTASH_REDIS_REST_URL=<YOUR_URL>export UPSTASH_REDIS_REST_TOKEN=<YOUR_TOKEN>

Deploy#

Run in the top folder:

cdk synthcdk bootstrapcdk deploy

Visit the output URL.