nixos/factorio: add allowedPlayers option to manage the whitelist (#350769)

  } // cfg.extraSettings;

  serverSettingsString = builtins.toJSON (lib.filterAttrsRecursive (n: v: v != null) serverSettings);

  serverSettingsFile = pkgs.writeText "server-settings.json" serverSettingsString;

  serverAdminsFile = pkgs.writeText "server-adminlist.json" (builtins.toJSON cfg.admins);

  playerListOption = name: list:

    lib.optionalString (list != [])

      "--${name}=${pkgs.writeText "${name}.json" (builtins.toJSON list)}";

  modDir = pkgs.factorio-utils.mkModDirDrv cfg.mods cfg.mods-dat;

in

{

        '';

      };

      allowedPlayers = lib.mkOption {

        # I would personally prefer for `allowedPlayers = []` to mean "no-one

        # can connect" but Factorio seems to ignore empty whitelists (even with

        # --use-server-whitelist) so we can't implement that behaviour, so we

        # might as well match theirs.

        type = lib.types.listOf lib.types.str;

        default = [];

        example = [ "Rseding91" "Oxyd" ];

        description = ''

          If non-empty, only these player names are allowed to connect. The game

          will not be able to save any changes made in-game with the /whitelist

          console command, though they will still take effect until the server

          is restarted.

          If empty, the whitelist defaults to open, but can be managed with the

          in-game /whitelist console command (see: /help whitelist), which will

          cause changes to be saved to the game's state directory (see also:

          `stateDirName`).

        '';

      };

      # Opting not to include the banlist in addition the the whitelist because:

      # - banlists are not as often known in advance,

      # - losing banlist changes on restart seems much more of a headache.

      admins = lib.mkOption {

        type = lib.types.listOf lib.types.str;

        default = [];

      extraSettings = lib.mkOption {

        type = lib.types.attrs;

        default = {};

        example = { admins = [ "username" ];};

        example = { max_players = 64; };

        description = ''

          Extra game configuration that will go into server-settings.json

        '';

          }"

          (lib.optionalString cfg.loadLatestSave "--start-server-load-latest")

          (lib.optionalString (cfg.mods != []) "--mod-directory=${modDir}")

          (lib.optionalString (cfg.admins != []) "--server-adminlist=${serverAdminsFile}")

          (playerListOption "server-adminlist" cfg.admins)

          (playerListOption "server-whitelist" cfg.allowedPlayers)

          (lib.optionalString (cfg.allowedPlayers != []) "--use-server-whitelist")

        ];

        # Sandboxing