docs: def glances_logger(env_key='LOG_CFG'):
      """Build and return the logger.
  
      env_key define the env var where a path to a specific JSON logger
              could be defined
  
      :return: logger -- Logger instance
      """
      _logger = logging.getLogger()
  
      # By default, use the LOGGING_CFG logger configuration
      config = LOGGING_CFG
  
      # Check if a specific configuration is available
      user_file = os.getenv(env_key, None)
      if user_file and os.path.exists(user_file):
          # A user file as been defined. Use it...
          with open(user_file, 'rt') as f:
              config = json.load(f)
  
      # Load the configuration
      logging.config.dictConfig(config)
  
      return _logger