Allow .subscribe() to accept array of topics

[WaleedAshraf]

As discussed in these comments,
#289 (comment)
#289 (comment)
by @ThisIsMissEm and @tulios.

The limitation on KafaJS is that it doesn't let you subscribe to multiple topics at once with an array of topics. That fixes the issues of having multiple consumers for multiple topics.

It's be something like

await consumer.subscribe([
	{ topic: 'topic-a', fromBeginning: true },
	{ topic: 'topic-b', fromBeginning: true }
])

Implementation
It can be possible to pass the array of topics to .subscribe() method, and it will be used as const topicsToSubscribe = [] here https://github.com/tulios/kafkajs/blob/master/src/consumer/index.js#L163

[tulios]

@WaleedAshraf it's not possible to pass an array but you can call subscribe multiple times or use subscribe with a regexp.

[WaleedAshraf]

@tulios, sorry, maybe I misunderstood the comment in other issues.
You mean it is possible to do this:

const kafka = new Kafka({
  clientId: 'my-app',
  brokers: ['kafka1:9092', 'kafka2:9092']
})

const consumer1 = kafka.consumer({ groupId: 'test-group' })

await consumer1.connect()
await consumer1.subscribe({ topic: 'topic-a', fromBeginning: true })
await consumer1.subscribe({ topic: 'topic-b', fromBeginning: true })
await consumer1.subscribe({ topic: 'topic-c', fromBeginning: true })

The groupId is the same, and the consumer is subscribed to multiple topics.

[tulios]

Yes, this is possible and used in production. You can also do:
await consumer1.subscribe({ topic: /topic-*/, fromBeginning: true })

[WaleedAshraf]

Thanks, 👍 That solves my problem. I'll close this issue.