AWS CDK - Python Lambda

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 2022/06/22 

Quick walk-though on how to publish a Python lambda that uses libraries not included in native Python container.

Read on to see the new AWS Lambda Python module in action.

The example below uses TypeScript to describe a cloud environment and upload a Python lambda function. Why not use the Python AWS CDK? We certainly could, but I prefer TypeScript as it has more documentation examples online.

Prerequisites

Follow all instructions on cdkworkshop to setup AWS CLI, AWS CDK and NodeJS.

Install NPM with NVM. Blog post here.

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curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.1/install.sh | bash
nvm install node
nvm use node

Install AWS CDK v2. Full documentation here.

1	npm install aws-cdk-lib

Setup AWS Account and user. Guide here.

1	aws configure

Install Docker. Full documentation here.

1	brew install docker

Initialize

Create new directory and initialize with CDK.

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mkdir ts_cdk_with_python_lambda
cd ts_cdk_with_python_lambda
cdk init app --language typescript

Install Amazon Lambda Python Library.

1 2	npm i @aws-cdk/aws-lambda-python-alpha npm install

Lambda and API Gateway

Create new file lambda_python/main.py which will contain our lambda function. Notice how this file uses the requests library to make a HTTP GET request to an external web service.

import requests

def handler(event, context):
    response = requests.get("https://api.ipify.org?format=json")
    print(response.text)
    return {
        'statusCode': 200,
        'headers': {
            'Content-Type': 'text/plain'
        },
        'body': f"You have hit {event['path']}\n"
                f"IP of lambda server: {response.json().get('ip', None)}"
    }

Create new requirements file lambda_python/requirements.txt

1	requests==2.28.0

Open lib/ts_cdk_with_python_lambda-stack.ts and add a new Python Function and associated API Gateway.

import { Stack, StackProps } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import { PythonFunction } from "@aws-cdk/aws-lambda-python-alpha";
import { aws_apigateway as apigw, aws_lambda as lambda } from "aws-cdk-lib";


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

    // Python Lambda Function
    const myPython = new PythonFunction(this, 'MyPythonHandler', {
      entry: './lambda_python',  // Folder containing lambda
      runtime: lambda.Runtime.PYTHON_3_9,  // Python version
      index: 'main.py',  // Name of Python file
      handler: 'handler'  // Name of method
    });

    // API Gateway
    new apigw.LambdaRestApi(this, 'MyPythonEndpoint', {
      handler: myPython
    })
  }
}

Full documentation on PythonFunction.

Deploy

Bootstrap your AWS account (if first time running AWS CDK). Then deploy!

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cdk bootstrap
cdk diff
cdk deploy

Answer “yes” to prompts. If successful, you should see output with your new API URL.

1 2	Outputs: TsCdkWithPythonLambdaStack.MyPythonEndpointABC = https://xyz.execute-api.us-west-2.amazonaws.com/prod/

Open the API Gateway URL in a browser and check for text output similar to below:

1 2	You have hit / IP of lambda server: x.x.x.x

Congratulations on using the new AWS Lambda Python module!

Bonus

Upload to GitHub.

git add .
git commit -m "python lambda"
git remote add origin https://github.com/<user>/ts_cdk_with_python_lambda.git
git push -u origin main

GitHub ts_cdk_with_python_lambda repo.

References

Author：Martin

Link：https://dbnservers.net/cloud/aws-cdk-python-lambda/

Publish date：June 22nd 2022, 1:00:00 pm

Update date：February 8th 2023, 3:30:42 am

License：creative commons 4.0

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CATALOG

1. Prerequisites
2. Initialize
3. Lambda and API Gateway
4. Deploy
5. Bonus
6. References