nixos darkhttpd: module to enable darkhttpd

nixos/modules/module-list.nix

@@ -802,6 +802,7 @@
   ./services/web-apps/zabbix.nix
   ./services/web-servers/apache-httpd/default.nix
   ./services/web-servers/caddy.nix
+  ./services/web-servers/darkhttpd.nix
   ./services/web-servers/fcgiwrap.nix
   ./services/web-servers/hitch/default.nix
   ./services/web-servers/hydron.nix

nixos/modules/services/web-servers/darkhttpd.nix

@@ -0,0 +1,77 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.darkhttpd;
+
+  args = concatStringsSep " " ([
+    cfg.rootDir
+    "--port ${toString cfg.port}"
+    "--addr ${cfg.address}"
+  ] ++ cfg.extraArgs
+    ++ optional cfg.hideServerId             "--no-server-id"
+    ++ optional config.networking.enableIPv6 "--ipv6");
+
+in {
+  options.services.darkhttpd = with types; {
+    enable = mkEnableOption "DarkHTTPd web server";
+
+    port = mkOption {
+      default = 80;
+      type = ints.u16;
+      description = ''
+        Port to listen on.
+        Pass 0 to let the system choose any free port for you.
+      '';
+    };
+
+    address = mkOption {
+      default = "127.0.0.1";
+      type = str;
+      description = ''
+        Address to listen on.
+        Pass `all` to listen on all interfaces.
+      '';
+    };
+
+    rootDir = mkOption {
+      type = path;
+      description = ''
+        Path from which to serve files.
+      '';
+    };
+
+    hideServerId = mkOption {
+      type = bool;
+      default = true;
+      description = ''
+        Don't identify the server type in headers or directory listings.
+      '';
+    };
+
+    extraArgs = mkOption {
+      type = listOf str;
+      default = [];
+      description = ''
+        Additional configuration passed to the executable.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.darkhttpd = {
+      description = "Dark HTTPd";
+      wants = [ "network.target" ];
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        DynamicUser = true;
+        ExecStart = "${cfg.package}/bin/darkhttpd ${args}";
+        AmbientCapabilities = lib.mkIf (cfg.port < 1024) [ "CAP_NET_BIND_SERVICE" ];
+        Restart = "on-failure";
+        RestartSec = "2s";
+      };
+    };
+  };
+}