A Multi-Arch Flake Template that Stays Boring

A Multi-Arch Flake Template that Stays Boring

Thesis

A flake that only works on x86_64-linux surprises Darwin CI. List systems, loop with genAttrs, keep packages and shells inside. Not evaluated here (nix missing).

Mental model

  forEach system → packages.${system} / devShells.${system}

Worked examples

{
  description = "boring multi-arch template";
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  outputs = { self, nixpkgs }:
    let
      systems = [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
      forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f {
        pkgs = import nixpkgs { inherit system; };
      });
    in {
      packages = forAllSystems ({ pkgs }: { default = pkgs.hello; });
      devShells = forAllSystems ({ pkgs }: {
        default = pkgs.mkShell { packages = [ pkgs.hello ]; };
      });
    };
}

Re-verify current nixpkgs pins when you use this.

Trap

Hard-coding system = "x86_64-linux" at the top level.

Boring rule

Enumerate systems once; put every package and shell inside the loop.

Try this

1. Add formatter/checks per system.
2. Compare nix flake init templates.
3. Grow into flake-parts perSystem if needed.

Sources

• Nix flakes manual