crate2nix

> Since package builds of node/python/ruby packages depend on stuff outside of the package dir in the tree, you need that mapping between versions and commits. > Using nix without nixpkgs may be fine for more scoped use but seems hard to justify for a platform like Railway. Nixpkgs isn't all-or-nothing. You're right that Nixpkgs itself rarely packages more than one version of something, but the standard approach for "language package managers" is that you use a tool like crate2nix[0] which automatically generates pinned derivations for all of your dependencies.[1] For system dependencies which aren't covered by your language package manager.. you're basically in the same position as for something like Debian: you can either pull it from Nixpkgs (and give up control beyond "which Nixpkgs am I on?") or you can write/fork your own package. O

It's crate2nix: https://github.com/kolloch/crate2nix

Yes, you will have to package it if it's not already in nixpkgs. The good news is once you learn how, it's basically trivial with crate2nix[0], which can autogenerate nix derivations from rust crates [0] https://github.com/kolloch/crate2nix

Fine-grain depedencies are crucial, but vendoring is terrible. Check out https://github.com/kolloch/crate2nix/ https://github.com/input-output-hk/haskell.nix for technical solutions to getting the best of both worlds. Sorry, but there's just no way DPkg/APT and RPM/Yum are going to keep up here very well.

Is this harder to achieve for the Rust ecosystem (due to some properties of Haskell perhaps)? You can actually do this today. The buildRustCrate function in nixpkgs creates a derivation for a single Rust crate. You can combine this with crate2nix [1] to make derivations for a crate and all its dependencies in a Cargo.lock file. Every compiled crate will be a separate output in the Nix store and you can upload them to a binary cache such as Cachix. This is what I have been using for CI in many of my Rust projects in combination with Cachix to get very fast builds. [1] https://github.com/kolloch/crate2nix

crate2nix is better maintained alternative to carnix: https://github.com/kolloch/crate2nix The cache is still useful though if you think about CI builds or having a common project in a team.