text: const fs   = require('fs');
  const path = require('path');
  
  const WORKING_DIR = process.cwd();
  // by default, when no config file exists, it must returns json
  const CONFIG_TYPE = fs.existsSync(path.join(WORKING_DIR, 'config.js')) ? 'js' : 'json';
  
  module.exports = {
    WORKING_DIR,
    CONFIG_TYPE,
  
    BACKUP_DIR          : path.join(WORKING_DIR, 'backup'),
    PUBLIC_DIR          : path.join(WORKING_DIR, 'public'),
    MIDDLEWARE_DIR      : path.join(WORKING_DIR, 'middleware'),
    CONFIG_FILE         : path.join(WORKING_DIR, `config.${CONFIG_TYPE}`),
    CONFIG_RUNTIME_FILE : path.join(WORKING_DIR, `config-runtime.${CONFIG_TYPE}`),
  
  
    RELOAD_ALL_WORKERS    : 'reload-all',
    RELOAD_ONE_WORKER     : 'reload',
    DRY_RELOAD_ONE_WORKER : 'dry-reload',
    SHUTDOWN_ONE_WORKER   : 'shutdown',
  
    // attribute used in req[UID] to store uid
    UID : Symbol('requestUID')
  };
  