From c37e40d9ff9f7c20d6f64dff80a55368c4dbb763 Mon Sep 17 00:00:00 2001
From: Ben Millwood <thebenmachine+git@gmail.com>
Date: Wed, 23 Oct 2024 15:39:22 +0100
Subject: [PATCH] nixos/factorio: add allowedPlayers

This writes a whitelist file and instructs the server process to use it.
I opted not to give the same treatment to the banlist because (as
explained in the comments) mutability and persistence seems more
important for bans, and they're less often known in advance.
---
 nixos/modules/services/games/factorio.nix | 32 +++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/services/games/factorio.nix b/nixos/modules/services/games/factorio.nix
index 7d5014e006f9..3e89c01dc841 100644
--- a/nixos/modules/services/games/factorio.nix
+++ b/nixos/modules/services/games/factorio.nix
@@ -36,7 +36,9 @@ let
   } // 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
 {
@@ -59,6 +61,30 @@ 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 = [];
@@ -298,7 +324,9 @@ in
           }"
           (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