nixos/syncplay: add saltFile and extraArgs option (#220096)

Co-authored-by: Sandro <sandro.jaeckel@gmail.com>

nixos/modules/services/networking/syncplay.nix

@@ -8,7 +8,8 @@ let
   cmdArgs =
     [ "--port" cfg.port ]
     ++ optionals (cfg.salt != null) [ "--salt" cfg.salt ]
-    ++ optionals (cfg.certDir != null) [ "--tls" cfg.certDir ];
+    ++ optionals (cfg.certDir != null) [ "--tls" cfg.certDir ]
+    ++ cfg.extraArgs;
 
 in
 {
@@ -33,7 +34,22 @@ in
         default = null;
         description = lib.mdDoc ''
           Salt to allow room operator passwords generated by this server
-          instance to still work when the server is restarted.
+          instance to still work when the server is restarted.  The salt will be
+          readable in the nix store and the processlist.  If this is not
+          intended use `saltFile` instead.  Mutually exclusive with
+          <option>services.syncplay.saltFile</option>.
+        '';
+      };
+
+      saltFile = mkOption {
+        type = types.nullOr types.path;
+        default = null;
+        description = lib.mdDoc ''
+          Path to the file that contains the server salt.  This allows room
+          operator passwords generated by this server instance to still work
+          when the server is restarted.  `null`, the server doesn't load the
+          salt from a file.  Mutually exclusive with
+          <option>services.syncplay.salt</option>.
         '';
       };
 
@@ -46,6 +62,14 @@ in
         '';
       };
 
+      extraArgs = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        description = lib.mdDoc ''
+          Additional arguments to be passed to the service.
+        '';
+      };
+
       user = mkOption {
         type = types.str;
         default = "nobody";
@@ -74,21 +98,31 @@ in
   };
 
   config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = cfg.salt == null || cfg.saltFile == null;
+        message = "services.syncplay.salt and services.syncplay.saltFile are mutually exclusive.";
+      }
+    ];
     systemd.services.syncplay = {
       description = "Syncplay Service";
-      wantedBy    = [ "multi-user.target" ];
+      wantedBy = [ "multi-user.target" ];
-      after       = [ "network-online.target" ];
+      after = [ "network-online.target" ];
 
       serviceConfig = {
         User = cfg.user;
         Group = cfg.group;
-        LoadCredential = lib.mkIf (cfg.passwordFile != null) "password:${cfg.passwordFile}";
+        LoadCredential = lib.optional (cfg.passwordFile != null) "password:${cfg.passwordFile}"
+          ++ lib.optional (cfg.saltFile != null) "salt:${cfg.saltFile}";
       };
 
       script = ''
         ${lib.optionalString (cfg.passwordFile != null) ''
           export SYNCPLAY_PASSWORD=$(cat "''${CREDENTIALS_DIRECTORY}/password")
         ''}
+        ${lib.optionalString (cfg.saltFile != null) ''
+          export SYNCPLAY_SALT=$(cat "''${CREDENTIALS_DIRECTORY}/salt")
+        ''}
         exec ${pkgs.syncplay-nogui}/bin/syncplay-server ${escapeShellArgs cmdArgs}
       '';
     };