Add describe config to kafkaclient

[jlandersen]

This allows fetching configs for topics and brokers, using the describe configs API (https://kafka.apache.org/protocol#The_Messages_DescribeConfigs).

Exposed as 3 methods on KafkaClient - describeConfigs which is a low level access to the API, and getTopicConfigs and getClusterConfigs on top. The request is supported on 0.11+.

As part of this there are a couple of new ways to send requests to brokers that are not with payloads.

Example use:

var kafka = require('..');
var client = new kafka.KafkaClient({
  kafkaHost: '127.0.0.1:9092'
});

client.on('ready', () => {
  // Get a broker ID and pass null for config names to get all
  const brokerId = Object.keys(client.brokerMetadata)[0];
  client.getClusterConfigs(brokerId, null, (err, result) => {
    console.log(result[brokerId]);
  });

  client.getTopicConfigs(['ExampleTopic', 'RebalanceTopic'], ['compression.type', 'message.format.version'], (err, result) => {
    console.log(result['ExampleTopic']);
    console.log(result['RebalanceTopic']);
  });
});

[jlandersen]

Seems like Travis is failing on all runs due to

(+) Error: Client request error: getaddrinfo ENOTFOUND api.nodesecurity.io api.nodesecurity.io:443
npm ERR! Test failed.  See above for more details.
The command "npm test" exited with 1.

Any ideas? 🤔

[jlandersen]

How do you know :-)

Closing in favour of #1081