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 = literalExample ''
          { demo = '''
              #!ipxe
              dhcp
              chain http://boot.ipxe.org/demo/boot.php
            ''';
          };
        '';
      };
    };

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

    boot.loader.grub.extraEntries =
      if config.boot.loader.grub.version == 2 then
        toString (map grubEntry scripts)
      else
        throw "iPXE is not supported with GRUB 1.";

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

}