Welcome to crate2nix

What does crate2nix do?

crate2nix builds your cargo-based rust project crate-by-crate with nix.

You can

• save time by only rebuilding changed crates hermetically in CI, and
• use cargo/rust-analyzer locally for a fast developing loop.

Dependency tree from cargo: It uses cargo_metadata to obtain the dependency tree from cargo. Therefore, it will use the exact same library versions as cargo and respect any locked down version in Cargo.lock.

Smart caching: It caches the builds of individual creates so that nix rebuilds exactly the crates that need to be rebuilt. Compare that to docker layers…

Nix ecosystem goodness: You can use all things that make the nix/NixOS ecosystem great, e.g. distributed/remote builds, build minimal docker images, deploy your binary as a service to the cloud, …

Out of the box support for libraries with non-rust dependencies: It builds on top of the buildRustCrate function from NixOS so that native dependencies of many rust libraries are already correctly fetched when needed. If your library with native dependencies is not yet supported, you can customize defaultCrateOverrides / crateOverrides, see below.

Optional Import From Derivation: Optional ability to generate the derived Cargo.nix during evaluation time so it does no need to be committed.

Easy to understand nix template: The actual nix code is generated via crate2nix/templates/build.nix.tera so you can fix/improve the nix code without knowing rust if all the data is already there.