AWS API Gateway and Lambda Function using Proxy integration.

Introduction

This is a very simple copy-pastable Python Lambda Function that integrates with API Gateway.

You can read more about the details here:

The Function

This function allows you easy access to the request's headers, query string parameters and body.

Where you're prompted to do your magic, you put all your logic.

Once you're ready finish off the response by setting the response code and the body, then return it to API Gateway.

import json

def lambda_handler(event, context):
   # Prepare a response dictionary as required by API Gateway
   response = {
        'isBase64Encoded': False,
        'statusCode': 0,
        'headers': {'Your-custom-header':'custom-header-value'},
        'body': ''
        }
   
   # Access the headers of the request
   requestHeaders = event['headers']
   myHeader = requestHeaders['my-header'] 
   
   # Access the query string parameters
   # for example if you called api.mysite.com/resource?myparam=custom
   queryParams = event['queryStringParameters']
   myParam = queryParams['myparam']
   
   # Access the body of the request into a dictionary
   requestBody = json.loads(event['body'])
   myField = requestBody['my-field']
   
   
   #-------------------
   # Do your magic here
   #-------------------
   
   
   # When ready to send the response, set the HTTP status code
   response['statusCode'] = 200
   
   # Then set a reply body if needed
   # this is always a JSON string
   response['body'] = json.dumps({'message':'All went well'})

   # And you're ready to send the response to API gateway!
   return response

Dependancies

The function has only one dependancy which is JSON. This comes with the Standard Library in Python.

Python Version

As it is the function is compatible with both Python 2.7 and Python 3.6.

Why did I do this?

I felt that there were a lot of doubts around the proxy integration and it also took myself a lot of reading and researching to make it work correctly.

I couldn't find a terribly clear example for Python, so here it is.

hopefully it will save some headeaches to a few, but let me know if it can be improved to suit specific needs.