nixpkgs/nixos/modules/system/boot/loader/grub/ipxe.nix

# This module adds a scripted iPXE entry to the GRUB boot menu.

{
  config,
  lib,
  pkgs,
  ...
}:

with lib;

let
  scripts = builtins.attrNames config.boot.loader.grub.ipxe;

  grubEntry = name: ''
    menuentry "iPXE - ${name}" {
      linux16 @bootRoot@/ipxe.lkrn
      initrd16 @bootRoot@/${name}.ipxe
    }

  '';

  scriptFile =
    name:
    let
      value = builtins.getAttr name config.boot.loader.grub.ipxe;
    in
    if builtins.typeOf value == "path" then value else builtins.toFile "${name}.ipxe" value;
in
{
  options = {
    boot.loader.grub.ipxe = mkOption {
      type = types.attrsOf (types.either types.path types.str);
      description = ''
        Set of iPXE scripts available for
        booting from the GRUB boot menu.
      '';
      default = { };
      example = literalExpression ''
        { demo = '''
            #!ipxe
            dhcp
            chain http://boot.ipxe.org/demo/boot.php
          ''';
        }
      '';
    };
  };

  config = mkIf (builtins.length scripts != 0) {

    boot.loader.grub.extraEntries = toString (map grubEntry scripts);

    boot.loader.grub.extraFiles = {
      "ipxe.lkrn" = "${pkgs.ipxe}/ipxe.lkrn";
    }
    // builtins.listToAttrs (
      map (name: {
        name = name + ".ipxe";
        value = scriptFile name;
      }) scripts
    );
  };

}