我的代码如下：

const kafka = require('kafka-node');
const Producer = kafka.Producer;
const client = new kafka.KafkaClient({kafkaHost: process.env.CLOUDKARAFKA_BROKERS});
const producer = new Producer(client);
producer.on('ready', () => {
    console.log('it has started');
});

producer.on('error', (err) => {
    console.log('kafka error is ' + err);
});

但不知怎么的它打印出了错误 kafka error is BrokerNotAvailableError: Broker not available