Add NixOS module for syslog-ng

nixos/modules/module-list.nix

@@ -135,6 +135,7 @@
   ./services/logging/logstash.nix
   ./services/logging/rsyslogd.nix
   ./services/logging/syslogd.nix
+  ./services/logging/syslog-ng.nix
   ./services/mail/dovecot.nix
   ./services/mail/freepops.nix
   ./services/mail/mail.nix

nixos/modules/services/logging/syslog-ng.nix

@@ -0,0 +1,83 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.syslog-ng;
+
+  syslogngConfig = pkgs.writeText "syslog-ng.conf" ''
+    @version: 3.5
+    @include "scl.conf"
+    ${cfg.extraConfig}
+  '';
+
+  ctrlSocket = "/run/syslog-ng/syslog-ng.ctl";
+  pidFile = "/run/syslog-ng/syslog-ng.pid";
+  persistFile = "/var/syslog-ng/syslog-ng.persist";
+
+  syslogngOptions = [
+    "--foreground"
+    "--module-path=${concatStringsSep ":" (["${pkgs.syslogng}/lib/syslog-ng"] ++ cfg.extraModulePaths)}"
+    "--cfgfile=${syslogngConfig}"
+    "--control=${ctrlSocket}"
+    "--persist-file=${persistFile}"
+    "--pidfile=${pidFile}"
+  ];
+
+in {
+
+  options = {
+
+    services.syslog-ng = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable the syslog-ng daemon.
+        '';
+      };
+      serviceName = mkOption {
+        type = types.str;
+        default = "syslog-ng";
+        description = ''
+          The name of the systemd service that runs syslog-ng. Set this to
+          <literal>syslog</literal> if you want journald to automatically
+          forward all logs to syslog-ng.
+        '';
+      };
+      extraModulePaths = mkOption {
+        type = types.listOf types.str;
+        default = [];
+        example = [ "${pkgs.syslogng_incubator}/lib/syslog-ng" ];
+        description = ''
+          A list of paths that should be included in syslog-ng's
+          <literal>--module-path</literal> option. They should usually
+          end in <literal>/lib/syslog-ng</literal>
+        '';
+      };
+      extraConfig = mkOption {
+        type = types.lines;
+        default = "";
+        description = ''
+          Configuration added to the end of <literal>syslog-ng.conf</literal>.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services."${cfg.serviceName}" = {
+      wantedBy = [ "multi-user.target" ];
+      preStart = "mkdir -p /{var,run}/syslog-ng";
+      serviceConfig = {
+        Type = "notify";
+        Sockets = "syslog.socket";
+        StandardOutput = "null";
+        Restart = "on-failure";
+        ExecStart = "${pkgs.syslogng}/sbin/syslog-ng ${concatStringsSep " " syslogngOptions}";
+      };
+    };
+  };
+
+}