Besides compute using Functions, the Serverless ecosystem gave developers many awesome managed tools for storage, queuing, messaging, secrets handling... However this diversity comes with a cost: our Functions’ handler code (on AWS Lambda for example) need to interact with potentially many external services.

During my first serverless projects, I often struggled to maintain a high level of code quality on Functions due to these numerous external interactions. Moreover, contrary to most traditional web frameworks, Serverless has no well-known convention to structure code, which does not help keeping the code clean and reusable.

I then decided to clearly separate the interactions with external services from business logic, taking inspiration from Hexagonal Architecture and Functional Programming.

In this talk, we'll see how applying these principles on Serverless Functions has helped improve understandability, ease testing, reduce cold starts and prevent nasty bugs. I will also showcase how to make the best use of Typescript for an easier implementation of these advanced patterns on your own Functions.