{ config, ... }:
{
  services.prometheus = {
    exporters = {
      node = {
        enable = true;
        enabledCollectors = [ "systemd" ];
      };
      postfix = {
        enable = true;
      };
    };
  };
  networking.firewall.allowedTCPPorts = [
    config.services.prometheus.exporters.node.port
    config.services.prometheus.exporters.postfix.port
  ];
}