Lets Build Our Own Lambda Faas

Let’s build our own lambda faas

Why?

As usual, as engineers, we build things out from scratch, in order to test our own understanding of something, and discover what we don’t know.

As they say,

“We did it not cuz it’s easy, but cuz we thought it was”

Background

This is part of the cloud services series I’ve been woring on recently. Here are a few other related blogs

• Liteginx proxy
• Lite Web Services
• Lite Containers

Intro

The idea here is to build something similar to aws lambda or gcp’s cloud functions, or if I were to use buzz words, “Serverless” :)

So what is it?

Serverless functions are a way to give developers a way to build out microservices as individual functions, where all the infrastructure and setup is abstracted away in a nice interface where you can write functions in your language of choice, which would then magically become HTTP endpoints or pub/sub consumers.

Benefits

• Approachable
• Can support everything u need as standard interfaces
• Pay as you go
• microservices without thinking much about it
• Easy/ automated deployment

Downsides

• Yet another abstraction
• You’re tied to the provider’s assumptions
• Hard to structure complex codebase scenarios
• Cold start problem

What’s out there…

Most cloud providers provide function as a service solutions, and there are a few open source ones as well

Let’s take a look at the most popular one, aws’s “lambda”

Here’s the gist of what we it offers

• Uses cloudformation to provision resources
• Your endpoints sit behind an api gateway that takes care of things like rate limiting, authentication, etc
• each funciton is sort of a basket microservice which gets its own dynamo db
• You can have your function be triggerered in response to an event coming to SQS through something called AES eventbridge/bus..

Here’s what we’ll offer

here’s what we typically need access to to build a modern web service

• A database, to store our user data and persistent state. A KV makes the most sense for faas, but we’ll attempt to support relational as well
• Access to a pubsub system, we’ll use nats. We do need to figure out how to abstract it away from the function code though
• API gateway, we’ll use liteginx cuz that can spin up additional blogs for features we’d need like rate limiting, authentication, etc

Architecture

Here’s the architecture of litefunctions, you can clearly both draw parallels with lambda, and appreciate the differences