code: protected DFSClient getDFSClient(HttpServletRequest request)
        throws IOException, InterruptedException {
      Configuration conf = new Configuration(masterConf);
      UnixUserGroupInformation.saveToConf(conf,
          UnixUserGroupInformation.UGI_PROPERTY_NAME, getUGI(request));
      return JspHelper.getDFSClient(request, conf);
    }
docs: getting a client for connecting to dfs