nix_for_rustaceans/slides/slides.md

marp	lang	title	description	theme	transition	paginate	_paginate
true	en-US	Marp CLI example	Hosting Marp slide deck on the web	nix_talk	fade	true	false

Nix for Rustaceans

Kateřina "Kate" Churanová

---

What is Nix

• Purely functional programming language
• Package manager
• Linux distribution (NixOS)
• multiplatform (Linux, Mac OS, BSD-ish)

---

What is Nix NOT

• Easy to learn
• Well documented
• Opinionated

---

Nix derivation

• "Package"
• evaluates to store derivation in /nix/store/
• 2n45ikclc8d5fhzkvg1197qlc2zk3s64-rustc-1.77.2.drv

---

Nix flake

• Unstable, but widely used
• New way of creating nix derivations
• Lock file version pinning
• Allows reproducibility

---

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };
  outputs =
    { self, nixpkgs }:
    {
      packages.x86_64-linux.default = nixpkgs.legacyPackages.x86_64-linux.hello;
      packages.x86_64-linux.foobar = nixpkgs.legacyPackages.x86_64-linux.fortune;
    };
}

---

---

Nix developer shell

• nix develop
• builds all flake dependencies, but not the flake itself
• sets up the development environment

---

Nix direnv

• https://github.com/nix-community/nix-direnv
• Activates developer shell automatically

---

Frameworks

• Pure nix solution is usable, but tedious with ugly boilerplate
• Numtide: flake-utils
• Hercules CI: Flake Parts

---

Flake parts - Minimal modular framework

Dev environment management

• Devshell
• Devenv

Rust project building

• NCI (Nix cargo integration)

---

Basic flake parts project

{
  inputs = {
    flake-parts.url = "github:hercules-ci/flake-parts";
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  outputs = inputs@{ flake-parts, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      imports = [
        # Modules go here
      ];
      systems = [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
      perSystem = { config, self', inputs', pkgs, system, ... }: {
        packages.default = pkgs.hello;
      };
    };
}

---

Fun begins with Rust

flake.nix

  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
    nci = {
      url = "github:yusdacra/nix-cargo-integration";
      inputs.nixpkgs.follows = "nixpkgs";
    };
    flake-parts = {
      url = "github:hercules-ci/flake-parts";
      inputs.nixpkgs-lib.follows = "nixpkgs";
    };
  };

---

outputs = inputs @ {
    flake-parts,
    nci,
    ...
  }:
    flake-parts.lib.mkFlake {inherit inputs;} {
      systems = ["x86_64-linux"];
      imports = [
        nci.flakeModule
        ./crates.nix
      ];
      perSystem = {
        pkgs,
        config,
        ...
      }: let
        crateName = "my-crate"
        crateOutputs = config.nci.outputs.${crateName};
      in {
        devShells.default = crateOutputs.devShell;
        packages.default = crateOutputs.packages.release;
      };
    };

---

crates.nix

{...}: {
  perSystem = {
    pkgs,
    config,
    ...
  }: let
    crateName = "my-crate";
  in {
    nci.projects."simple".path = ./.;
    nci.crates.${crateName} = {};
  };
}

---

Why all of this though?

• Reproducible environment with pinned Rust version
• Predictable dependencies
• Plenty of other tools for your disposal
• Extremely simple generation of lightweight OCI containers

---

          packages.container = pkgs.dockerTools.streamLayeredImage {
            name = crateName;
            tag = "latest";
            contents = [ ];
            config = {
              Cmd = [ "${crateOutputs.packages.release}/bin/my-crate" ];
            };
          };