> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Deploy a Serverless API with AWS CDK and AWS Lambda

<Card title="GitHub Repository" icon="github" href="https://github.com/upstash/redis-js/tree/main/examples/aws-cdk-typescript" horizontal>
  You can find the project source code on GitHub.
</Card>

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](https://docs.aws.amazon.com/cdk/latest/guide/home.html).

### Prerequisites

* Complete all steps in [Getting started with the AWS CDK](https://docs.aws.amazon.com/cdk/v2/guide/getting_started.html)

### 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.

```shell theme={"system"}
mkdir counter-cdk && cd counter-cdk
```

Initialize a new CDK project.

```shell theme={"system"}
cdk init app --language typescript
```

Install `@upstash/redis`.

```shell theme={"system"}
npm install @upstash/redis
```

### Counter Function Setup

Create `/api/counter.ts`.

```ts /api/counter.ts theme={"system"}
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`.

```ts /lib/counter-cdk-stack.ts theme={"system"}
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](https://console.upstash.com) or [Upstash CLI](https://github.com/upstash/cli) and export `UPSTASH_REDIS_REST_URL` and `UPSTASH_REDIS_REST_TOKEN` to your environment.

```shell theme={"system"}
export UPSTASH_REDIS_REST_URL=<YOUR_URL>
export UPSTASH_REDIS_REST_TOKEN=<YOUR_TOKEN>
```

### Deploy

Run in the top folder:

```shell theme={"system"}
cdk synth
cdk bootstrap
cdk deploy
```

Visit the output URL.