GitHub Repository

You can find the project source code on GitHub.

​
Prerequisites

​
Project Setup

Create and navigate to a directory named counter-cdk. 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

​
Counter Function Setup

Create a folder named api under lib 
mkdir lib/api
Create /lib/api/requirements.txt
/lib/api/requirements.txt
upstash-redis
Create /lib/api/index.py
/lib/api/index.py
from upstash_redis import Redis

redis = Redis.from_env()

def handler(event, context):
    count = redis.incr('counter')
    return {
        'statusCode': 200,
        'body': f'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 path from 'path';

export class CounterCdkStack extends cdk.Stack {
  constructor(scope: Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const counterFunction = new lambda.Function(this, 'CounterFunction', {
      code: lambda.Code.fromAsset(path.join(__dirname, 'api'), {
        bundling: {
          image: lambda.Runtime.PYTHON_3_9.bundlingImage,
          command: [
            'bash', '-c',
            'pip install -r requirements.txt -t /asset-output && cp -au . /asset-output'
          ],
        },
      }),
      runtime: lambda.Runtime.PYTHON_3_9,
      handler: 'index.handler',
      environment: {
        UPSTASH_REDIS_REST_URL: process.env.UPSTASH_REDIS_REST_URL || '',
        UPSTASH_REDIS_REST_TOKEN: process.env.UPSTASH_REDIS_REST_TOKEN || '',
      },
    });

    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 synth
cdk bootstrap
cdk deploy
Visit the output url.