The Rust on AWS Lambda project consists of multiple crates that make it possible to run programs written in Rust directly as functions in AWS Lambda, while keeping a low footprint with regards to memory consumption, bundle size, and start-up speed.

Comparison to other projects

AWS Lambda does not officially support Rust. To enable using Rust with lambda, great projects such as rust-crowbar and serverless-rust were created. They leverage Rust’s C interoperability to “embed” Rust code into lambda supported language runtimes (in this case Python and Node.js respectively).

This project forgoes embedding and instead leverages lambda’s official Go support. With Go, lambda runs a standard Linux binary containing a server and then sends it gob-encoded messages via rpc. This project reimplements all that machinery in Rust, using rust-gob for gob support and a custom tokio server runtime. Lambda does not care that the Linux binary it runs is written in Rust rather than Go as long as they behave the same.

Due to the no-overhead method of adding Rust support, a project deployed to lambda using this runtime should match (and might possibly exceed) the performance of a similar project written in Go.