➜  nix_images cat custom-iso.nix
{ nixpkgs ? <nixpkgs>, system? "x86_64-linux" }:

let
    myisoconfig = { pkgs, ...}: {
        imports = [
            "${nixpkgs}/nixos/modules/installer/cd-dvd/iso-image.nix"
        ];

        networking.hostName = "mynixos";
        environment.systemPackages = with pkgs; [ tmux vim];
        users.extraUsers.root.password = "mynixos";

    boot.loader = {
        grub = {
            enable = pkgs.lib.mkForce true;
            efiSupport = true;
            efiInstallAsRemovable = true;
            device = "nodev";
        };
        };
      };

    evalNixos = configuration: import "${nixpkgs}/nixos" {
        inherit system configuration;
    };

in { iso = (evalNixos myisoconfig).config.system.build.isoImage; }
➜  nix_images