Setting Up a Dev Shell with Nix Flakes

Tue, 20 Jan 2026 00:00:00 +0000

Every project I join has a different setup doc. Half the steps are outdated. Nix flakes fix this — one file, one command, done.

Here’s a minimal flake.nix for a Node + Python project:

{
 inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

 outputs = { nixpkgs, ... }:
 let
 system = "x86_64-linux";
 pkgs = nixpkgs.legacyPackages.${system};
 in {
 devShells.${system}.default = pkgs.mkShell {
 packages = with pkgs; [
 nodejs_22
 python312
 python312Packages.pip
 ];

 shellHook = ''
 echo "dev shell ready"
 '';
 };
 };
}

Run nix develop and you’re in. Everyone on the team gets the exact same versions. No “works on my machine”, no version managers, no install scripts.

Nix on Dan's Blog

Setting Up a Dev Shell with Nix Flakes