nginx: Add alias configuration option for hosts and locations.

It's like root, but doesn't keep the prefix.

nixos/modules/services/web-servers/nginx/default.nix

@@ -158,6 +158,7 @@ let
           server_name ${serverName} ${concatStringsSep " " vhost.serverAliases};
           ${acmeLocation}
           ${optionalString (vhost.root != null) "root ${vhost.root};"}
+          ${optionalString (vhost.alias != null) "alias ${vhost.alias};"}
           ${optionalString (vhost.globalRedirect != null) ''
             return 301 http${optionalString ssl "s"}://${vhost.globalRedirect}$request_uri;
           ''}
@@ -180,6 +181,7 @@ let
       ${optionalString (config.index != null) "index ${config.index};"}
       ${optionalString (config.tryFiles != null) "try_files ${config.tryFiles};"}
       ${optionalString (config.root != null) "root ${config.root};"}
+      ${optionalString (config.alias != null) "alias ${config.alias};"}
       ${config.extraConfig}
     }
   '') locations);

nixos/modules/services/web-servers/nginx/location-options.nix

@@ -45,6 +45,15 @@ with lib;
       '';
     };
 
+    alias = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      example = "/your/alias/directory";
+      description = ''
+        Alias directory for requests.
+      '';
+    };
+
     extraConfig = mkOption {
       type = types.lines;
       default = "";

nixos/modules/services/web-servers/nginx/vhost-options.nix

@@ -89,6 +89,15 @@ with lib;
       '';
     };
 
+    alias = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      example = "/data/webserver/docs";
+      description = ''
+        The path of the web alias directory.
+      '';
+    };
+
     default = mkOption {
       type = types.bool;
       default = false;