ostinato: add ostinato in NixOS services

nixos/modules/module-list.nix

@@ -331,6 +331,7 @@
   ./services/networking/openfire.nix
   ./services/networking/openntpd.nix
   ./services/networking/openvpn.nix
+  ./services/networking/ostinato.nix
   ./services/networking/polipo.nix
   ./services/networking/prayer.nix
   ./services/networking/privoxy.nix

nixos/modules/services/networking/ostinato.nix

@@ -0,0 +1,104 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  pkg = pkgs.ostinato;
+  cfg = config.services.ostinato;
+  configFile = pkgs.writeText "drone.ini" ''
+    [General]
+    RateAccuracy=${cfg.rateAccuracy}
+
+    [RpcServer]
+    Address=${cfg.rpcServer.address}
+
+    [PortList]
+    Include=${concatStringsSep "," cfg.portList.include}
+    Exclude=${concatStringsSep "," cfg.portList.exclude}
+  '';
+
+in
+{
+
+  ###### interface
+
+  options = {
+
+    services.ostinato = {
+
+      enable = mkEnableOption "Ostinato agent-controller (Drone)";
+
+      port = mkOption {
+        type = types.int;
+        default = 7878;
+        description = ''
+          Port to listen on.
+        '';
+      };
+
+      rateAccuracy = mkOption {
+        type = types.enum [ "High" "Low" ];
+        default = "High";
+        description = ''
+          To ensure that the actual transmit rate is as close as possible to
+          the configured transmit rate, Drone runs a busy-wait loop.
+          While this provides the maximum accuracy possible, the CPU
+          utilization is 100% while the transmit is on. You can however,
+          sacrifice the accuracy to reduce the CPU load.
+        '';
+      };
+
+      rpcServer = {
+        address = mkOption {
+          type = types.string;
+          default = "0.0.0.0";
+          description = ''
+            By default, the Drone RPC server will listen on all interfaces and
+            local IPv4 adresses for incoming connections from clients.  Specify
+            a single IPv4 or IPv6 address if you want to restrict that.
+            To listen on any IPv6 address, use ::
+          '';
+        };
+      };
+
+      portList = {
+        include = mkOption {
+          type = types.listOf types.string;
+          default = [];
+          example = ''[ "eth*" "lo*" ]'';
+          description = ''
+            For a port to pass the filter and appear on the port list managed
+            by drone, it be allowed by this include list.
+          '';
+        };
+        exclude = mkOption {
+          type = types.listOf types.str;
+          default = [];
+          example = ''[ "usbmon*" "eth0" ]'';
+          description = ''
+            A list of ports does not appear on the port list managed by drone.
+          '';
+        };
+      };
+
+    };
+
+  };
+
+  ###### implementation
+
+  config = mkIf cfg.enable {
+
+    environment.systemPackages = [ pkg ];
+
+    systemd.services.drone = {
+      description = "Ostinato agent-controller";
+      wantedBy = [ "multi-user.target" ];
+      script = ''
+        ${pkg}/bin/drone ${toString cfg.port} ${configFile}
+      '';
+    };
+
+  };
+
+}