Ever wondered what actually happens when you invoke a Lambda function? Not the API layer but the execution layer. What runs your code, how it's isolated, and how AWS gets cold starts low enough to be usable?
I wanted to understand that deeply. So I built it.
This is a breakdown of how I built a Firecracker-based serverless runtime from scratch, the architectural decisions I made, and what the numbers look like.
The problem: cold starts
Every serverless platform faces the same fundamental tension. You want functions to start instantly, but strong isolation requires spinning up a fresh environment per invocation.
