code: func setupResolvConf(config *config.Config) {
  	if config.ResolvConf != "" {
  		return
  	}
  
  	config.ResolvConf = defaultResolvConf
  	pids, err := procfs.PidOf("systemd-resolved")
  	if err != nil {
  		logrus.Errorf("unable to check systemd-resolved status: %s", err)
  		return
  	}
  	if len(pids) > 0 && pids[0] > 0 {
  		_, err := os.Stat(alternateResolvConf)
  		if err == nil {
  			logrus.Infof("systemd-resolved is running, so using resolvconf: %s", alternateResolvConf)
  			config.ResolvConf = alternateResolvConf
  			return
  		}
  		logrus.Infof("systemd-resolved is running, but %s is not present, fallback to %s", alternateResolvConf, defaultResolvConf)
  	}
  }
docs: // setupResolvConf sets the appropriate resolv.conf file if not specified
  // When systemd-resolved is running the default /etc/resolv.conf points to
  // localhost. In this case fetch the alternative config file that is in a
  // different path so that containers can use it
  // In all the other cases fallback to the default one