Serverless Python API with Redis - Upstash Documentation

You can find the project source code on GitHub.

This tutorial shows how to build a serverless API for Page View Counter with Python and Redis. The API will the count page views and show it in JSON format.

Prerequisites#

Complete all steps in Getting started with the AWS CDK

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 Redisredis = 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 synthcdk bootstrapcdk deploy

Visit the output url.