dotfiles/nixos/modules/telegraf.nix

{
  config,
  lib,
  pkgs,
  ...
}:
with lib; let
  cfg = config.services.telegraf-magic;

  settingsFormat = pkgs.formats.toml {};
  configFile = settingsFormat.generate "config.toml" cfg.settings;
in {
  options = {
    services.telegraf-magic = {
      enable = mkEnableOption (lib.mdDoc "telegraf server");

      package = mkOption {
        default = pkgs.telegraf;
        defaultText = literalExpression "pkgs.telegraf";
        description = lib.mdDoc "Which telegraf derivation to use";
        type = types.package;
      };

      settings = mkOption {
        default = {};
        description = lib.mdDoc "Extra configuration options for telegraf";
        type = settingsFormat.type;
        example = {
          outputs.influxdb = {
            urls = ["http://localhost:8086"];
            database = "telegraf";
          };
          inputs.statsd = {
            service_address = ":8125";
            delete_timings = true;
          };
        };
      };

      systemd = mkOption {
        default = {};
        description = lib.mdDoc "Applied to `systemd.services.telegraf`.";
        type = types.unspecified;
      };
    };
  };

  config = mkIf cfg.enable {
    systemd.services.telegraf = mkMerge [
      (cfg.systemd)
      {
        description = "Telegraf Agent";
        wantedBy = ["multi-user.target"];
        after = ["network-online.target"];
        serviceConfig = {
          ExecStart = "${cfg.package}/bin/telegraf -config ${configFile}";
          ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
          RuntimeDirectory = "telegraf";
          User = "telegraf";
          Group = "telegraf";
          Restart = "on-failure";
          # for ping probes
          AmbientCapabilities = ["CAP_NET_RAW"];
        };
      }
    ];

    users.users.telegraf = {
      uid = config.ids.uids.telegraf;
      group = "telegraf";
      description = "telegraf daemon user";
    };

    users.groups.telegraf = {};
  };
}