Closing the Nix Gap: From Environments to Packaged Applications for Rust
Should I use crate2nix, cargo2nix, or naersk for packaging my Rust application? — (@jvmncs) January 21, 2025
This tweet shows a common problem in Nix: "Should I use crate2nix, cargo2nix, or naersk for packaging my Rust application?"
devenv solved this for development environments differently: instead of making developers package everything with Nix, we provide tools through a simple languages.rust.enable . You get cargo , rustc , and rust-analyzer in your shell without understanding Nix packaging.
But when you're ready to deploy, you face the same problem: which lang2nix tool should you use? Developers don't want to compare crate2nix vs cargo2nix vs naersk vs crane —they want a tested solution that works.
devenv now provides languages.rust.import , which packages Rust applications using crate2nix. We evaluated the available tools and chose crate2nix, so you don't have to.
We've done this before. In PR #1500, we replaced fenix with rust-overlay for Rust toolchains because rust-overlay was better maintained. Users didn't need to change anything—devenv handled the transition while keeping the same languages.rust.enable = true interface.
One Interface for All Languages
The typical workflow:
Development: Enable the language ( languages.rust.enable = true ) to get tools like cargo , rustc , and rust-analyzer . Packaging: When ready to deploy, use languages.rust.import to package with Nix.
The same pattern works for all languages:
{ config , ... }: { # https://devenv.sh/languages languages = { rust . enable = true ; python . enable = true ; go . enable = true ; }; # https://devenv.sh/outputs outputs = { rust-app = config . languages . rust . import ./rust-app {}; python-app = config . languages . python . import ./python-app {}; go-app = config . languages . go . import ./go-app {}; }; }
Starting with Rust
languages.rust.import automatically generates Nix expressions from Cargo.toml and Cargo.lock .
Add the crate2nix input:
$ devenv inputs add crate2nix github:nix-community/crate2nix --follows nixpkgs
Import your Rust application:
{ config , ... }: let # ./app is the directory containing your Rust project's Cargo.toml myapp = config . languages . rust . import ./app {}; in { # Provide developer environment languages . rust . enable = true ; # Expose our application inside the environment packages = [ myapp ]; # https://devenv.sh/outputs outputs = { inherit myapp ; }; }
Build your application:
$ devenv build outputs.myapp
Other Languages
This API extends to other languages, each using the best packaging tool:
We've also started using uv2nix to provide a similar interface for Python in PR #2115.
That's it
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