nixos: add atftpd service

nixos/modules/module-list.nix

@@ -192,6 +192,7 @@
   ./services/network-filesystems/rsyncd.nix
   ./services/network-filesystems/samba.nix
   ./services/networking/amuled.nix
+  ./services/networking/atftpd.nix
   ./services/networking/avahi-daemon.nix
   ./services/networking/bind.nix
   ./services/networking/bitlbee.nix

nixos/modules/services/networking/atftpd.nix

@@ -0,0 +1,51 @@
+# NixOS module for atftpd TFTP server
+
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  cfg = config.services.atftpd;
+
+in
+
+{
+
+  options = {
+
+    services.atftpd = {
+
+      enable = mkOption {
+        default = false;
+        type = types.uniq types.bool;
+        description = ''
+          Whenever to enable the atftpd TFTP server.
+        '';
+      };
+
+      root = mkOption {
+        default = "/var/empty";
+        type = types.uniq types.string;
+        description = ''
+          Document root directory for the atftpd.
+        '';
+      };
+
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+
+    systemd.services.atftpd = {
+      description = "atftpd TFTP server";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      # runs as nobody
+      serviceConfig.ExecStart = "${pkgs.atftp}/sbin/atftpd --daemon --no-fork --bind-address 0.0.0.0 ${cfg.root}";
+    };
+
+  };
+
+}