Serverless Python API with Redis - Upstash Documentation

GitHub Repository

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 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.

GitHub Repository

​Prerequisites

​Project Setup

​Counter Function Setup

​Counter Stack Setup

​Database Setup