RFC: Event Hander - Api Gateway Support

[Muthuveerappanv]

Description of the feature request

Event Handler Support for powertools-typescript, to handle API Gateway events & Appsync events

Problem statement

Lambda Powertools for python is a one-stop-shop for all variants of lambda we develop today : api-driven, event-driven, etc. Event Handler helps with that. This way, we don't have to introduce other framework/library to handle api-gateway, appsync, etc.

Summary

Event Handler Support for powertools-typescript eventHandler, to handle API Gateway events

Motivation

There are Nodejs routing frameworks in Typescript & Javascript - expressjs, koa, nestjs, fastify are very opinionated to their ecosystem and also have a heavy-foot print for serverless workloads. We need a light-weight routing library that is part of the powertools ecosystem for Typescript similar to the Powertools-Python

Proposal

Create a new package event-handler and start with API Gateway Proxy Event Handler and potentially add more features like - AppSync, ALB and Lambda Function URL. The package should be light-weight only dependent on Powertools Core libraries and not introduce any external packages

UX should support:

#413 (comment)

Code examples
https://awslabs.github.io/aws-lambda-powertools-python/latest/core/event_handler/api_gateway/

Benefits for you and the wider AWS community

• powertools will be the only major library/framework you will ever need for lambda development
• makes it easier for development teams to focus on creating middlewares, custom library around this one libarary, rather than creating different libraries for express, etc.

Describe alternatives you've considered

• lambda-api
• ts-lambda-api
• serverless-express

Related issues, RFCs

#1166

[dreamorosi]

Hi @Muthuveerappanv thank you for the request. Feature parity with the Python version is definitely something that we have in mind and we'll be looking at this feature in the future.

[willfarrell]

@Muthuveerappanv Have you looked at Middy? All modules in this repo support a middy-compatible middleware ready to go.

[michaelbrewer]

This would be really cool. Especially if we can do it via some class decorators and keep the UX clean.

[mikebroberts]

I think this is a good idea. I looked at the Middy version recently - the weird thing is that routing isn't actually a middleware function though (middleware wraps a pre-determined target; routing chooses what the target is) and so I think it would be good to have it in Powertools and not be concerned it's a duplication of Middy. (I ended up not using the Middy router)

FWIW I've typically been against the idea of internal routing, but I've come around to the idea in certain circumstances. I saw a discussion on twitter yesterday about the Powertools Python router, which made me write up some thoughts about when internal routing is / isn't a useful technique: https://blog.symphonia.io/posts/2022-07-20_lambda_event_routing