code: async function authenticate(database) {
      database[AUTH_RETRIES] = database[AUTH_RETRIES] || 0;
  
      try {
        await database.authenticate();
      } catch (e) {
        if (e.name !== 'SequelizeConnectionRefusedError') throw e;
        if (app.model[AUTH_RETRIES] >= 3) throw e;
  
        // sleep 2s to retry, max 3 times
        database[AUTH_RETRIES] += 1;
        app.logger.warn(`Sequelize Error: ${e.message}, sleep 2 seconds to retry...`);
        await sleep(2000);
        await authenticate(database);
      }
    }
docs: Authenticate to test Database connection.
  
  This method will retry 3 times when database connect fail in temporary, to avoid Egg start failed.
  @param {Application} database instance of sequelize