Minimal shell.nix for Ruby on Rails

shell.nix

let
  nixpkgs =
    import (builtins.fetchTarball {
      url = https://github.com/NixOS/nixpkgs/archive/f5dad40450d272a1ea2413f4a67ac08760649e89.tar.gz; # Pinned to unstable. Update by picking a SHA from https://status.nixos.org
    }) { };
in
nixpkgs.mkShell {
  buildInputs = [
    nixpkgs.ruby_3_1
    nixpkgs.nodejs-18_x
    nixpkgs.imagemagick
    nixpkgs.libiconv
    nixpkgs.libsass
    nixpkgs.pkg-config
    nixpkgs.postgresql_12
    nixpkgs.zlib
  ];
}