nixos: u9fs service module

nixos/modules/module-list.nix

@@ -228,6 +228,7 @@
   ./services/network-filesystems/rsyncd.nix
   ./services/network-filesystems/samba.nix
   ./services/network-filesystems/diod.nix
+  ./services/network-filesystems/u9fs.nix
   ./services/network-filesystems/yandex-disk.nix
   ./services/networking/amuled.nix
   ./services/networking/atftpd.nix

nixos/modules/services/network-filesystems/u9fs.nix

@@ -0,0 +1,75 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.u9fs;
+in
+{
+
+  options = {
+
+    services.u9fs = {
+
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = "Whether to run the u9fs 9P server for Unix.";
+      };
+
+      listenStreams = mkOption {
+        type = types.listOf types.str;
+        default = [ "564" ];
+        example = [ "192.168.16.1:564" ];
+        description = ''
+          Sockets to listen for clients on.
+          See <command>man 5 systemd.socket</command> for socket syntax.
+        '';
+      };
+
+      extraArgs = mkOption {
+        type = types.str;
+        default = "";
+        example = "-a none -u nobody";
+        description =
+          ''
+            Extra arguments to pass on invocation,
+            see <command>man 4 u9fs</command>
+          '';
+      };
+
+      fsroot = mkOption {
+        type = types.path;
+        default = "/";
+        example = "/srv";
+        description = "File system root to serve to clients.";
+      };
+
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+
+    systemd = {
+      sockets.u9fs = {
+        description = "U9fs Listening Socket";
+        wantedBy = [ "sockets.target" ];
+        inherit (cfg) listenStreams;
+        socketConfig.Accept = "yes";
+      };
+      services."u9fs@" = {
+        description = "9P Protocol Server";
+        reloadIfChanged = true;
+        requires = [ "u9fs.socket" ];
+        serviceConfig =
+          { ExecStart = "-${pkgs.u9fs}/bin/u9fs ${cfg.extraArgs} ${cfg.fsroot}";
+            StandardInput = "socket";
+            StandardError = "journal";
+          };
+      };
+    };
+
+  };
+
+}