code: func (c *Configurer) SetupDNSinContainerizedMounter(mounterPath string) {
  	resolvePath := filepath.Join(strings.TrimSuffix(mounterPath, "/mounter"), "rootfs", "etc", "resolv.conf")
  	dnsString := ""
  	for _, dns := range c.clusterDNS {
  		dnsString = dnsString + fmt.Sprintf("nameserver %s\n", dns)
  	}
  	if c.ResolverConfig != "" {
  		f, err := os.Open(c.ResolverConfig)
  		defer f.Close()
  		if err != nil {
  			klog.Error("Could not open resolverConf file")
  		} else {
  			_, hostSearch, _, err := parseResolvConf(f)
  			if err != nil {
  				klog.Errorf("Error for parsing the reslov.conf file: %v", err)
  			} else {
  				dnsString = dnsString + "search"
  				for _, search := range hostSearch {
  					dnsString = dnsString + fmt.Sprintf(" %s", search)
  				}
  				dnsString = dnsString + "\n"
  			}
  		}
  	}
  	if err := ioutil.WriteFile(resolvePath, []byte(dnsString), 0600); err != nil {
  		klog.Errorf("Could not write dns nameserver in file %s, with error %v", resolvePath, err)
  	}
  }
docs: // SetupDNSinContainerizedMounter replaces the nameserver in containerized-mounter's rootfs/etc/resolve.conf with kubelet.ClusterDNS