code: function serverClose (signal, done) {
    _logger.info('Process received ' + signal + ', exiting ....')
    if (done === undefined) {
      done = function () {
        process.exit(0)
      }
    }
    if (server) {
      server.close(done)
    } else {
      done()
    }
  }
docs: Closing the server
  @param signal the log message depending on the given signal.