nixpkgs/nixos/modules/services/monitoring/prometheus/exporters/systemd.nix

{
  config,
  pkgs,
  lib,
  ...
}:

let
  cfg = config.services.prometheus.exporters.systemd;
  inherit (lib) concatStringsSep;
in
{
  port = 9558;

  serviceOpts = {
    serviceConfig = {
      ExecStart = ''
        ${pkgs.prometheus-systemd-exporter}/bin/systemd_exporter \
          --web.listen-address ${cfg.listenAddress}:${toString cfg.port} ${concatStringsSep " " cfg.extraFlags}
      '';
      RestrictAddressFamilies = [
        # Need AF_UNIX to collect data
        "AF_UNIX"
      ];
    };
  };
}