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Better Python 3 AWS Lambda Handlers.

Currently, your only choice for making Python handlers for AWS Lambda is to create a function like so:

def handler(event, context):
    return True

This isn't ideal when you start dealing with more than one handler, or if you want to provide a configurable and reusable handler. This package provides three base classes, the Handler, the Request, and the Response handler.

The Handler class is a callable, you create a subclass off of this, instantiate it, and that's what you configure AWSλ to invoke.

Your Handler has to have a perform(self, request) method, this houses your handler's business logic, Handler.__call__ executes this function and expects a Response object.

The Response object behaves like a dictionary and an object, an attribute called serialized is returned to AWSλ.

The request argument in perform(self, request) is a Request object, and it houses the event and context parameters that AWSλ passes to your handler. Packaging those handler arguments into an object makes them available for transparent mutations, see mutton.apig.APIGatewayRequest for reference.

The foundation of this library is tiny, I recommend reviewing the main classes to further understand how to use this package.


pip install mutton
import mutton

class EchoHandler(mutton.Handler):
    """Echo handler."""

    def perform(self, request, **k):
        """Echo perform method."""
        response = mutton.Response()
        response.body = self.request.event
        return response

echo_handler = EchoHandler()

# `echo_handler` is now a callable function you can map your AWS Lambda function to


Fork this library and send over PRs, I will consider applications for contributors if two of your PRs gets merged and published.

pipenv sync --dev # setup
pipenv run pytest # test

Supported Event Sources

  • API Gateway mutton.apig
  • S3
  • DynamoDB
  • SNS
  • SES
  • SQS
  • Cognito
  • Cloudwatch Logs, Events


We want support for more event sources, I am willing to entertain PRs. You can use the mutton.apig submodule as an example of implementing more event sources.


Better AWS Lambda Handlers in Python





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