Fluid compute: How we built serverless servers

This post details the engineering effort behind Vercel's Fluid compute, specifically focusing on the development of a custom TCP-based transport protocol to enable HTTP streaming from AWS Lambda functions. This protocol allows for multiplexing multiple concurrent requests to a single Lambda instance, breaking the traditional one-invocation-per-instance model. A new `compute-resolver` service was introduced to manage routing requests to Vercel Function Router pods, ensuring efficient reuse of established TCP connections and preventing hot-spotting. The Rust-based core acting as glue between infrastructure and user code is also highlighted.