egg-kafka/lib/index.js

Kafka plugin for egg

'use strict';

const assert = require('assert');
const Client = require('./Client');
const Producer = require('./Producer');
const HighLevelProducer = require('./HighLevelProducer');
const Comsumer = require('./Consumer');

module.exports = app => {
  app.addSingleton('kafka', createOneClient);
};

function createOneClient(config, app) {
  assert(config.host && config.port,
    `[egg-kafka] 'host: ${config.host}', 'port: ${config.port}'are required on config`);

  app.coreLogger.info('[egg-kafka] connecting %s:%s', config.host, config.port);

  // create Client instance
  const clients = Client(config.host + ':' + config.port);

  /**
   * Producer Instance
   * @param {boolean} args optional parameters
   * @return {Producer} -
   */
  function producer(...args) {
    if (args.length === 1) {
      return Producer(clients, args[0], app.coreLogger);
    }
    return Producer(clients, app.coreLogger);
  }

  /**
   * HighLevelProducer Instance
   * @param {boolean} args optional parameters
   * @return {HighLevelProducer} -
   */
  function highLevelProducer(...args) {
    if (args.length === 1) {
      return HighLevelProducer(clients, args[0], app.coreLogger);
    }
    return HighLevelProducer(clients, app.coreLogger);
  }

  /**
   * get Comsumer Instance function
   *@param {Object} payloads - Array,array of FetchRequest, FetchRequest is a JSON object {
   *   topic: 'topicName',
   *   offset: 0, //default 0
   * }
   *@param {Object} option - options for consumer, default:
   * {
   * groupId: 'kafka-node-group',//consumer group id, default `kafka-node-group`
   * // Auto commit config
   * autoCommit: true,
   * autoCommitIntervalMs: 5000,
   * // The max wait time is the maximum amount of time in milliseconds to block waiting if insufficient data is available at the time the request is issued, default 100ms
   * fetchMaxWaitMs: 100,
   * // This is the minimum number of bytes of messages that must be available to give a response, default 1 byte
   * fetchMinBytes: 1,
   * // The maximum bytes to include in the message set for this partition. This helps bound the size of the response.
   * fetchMaxBytes: 1024 * 1024,
   *  // If set true, consumer will fetch message from the given offset in the payloads
   * fromOffset: false,
   * // If set to 'buffer', values will be returned as raw buffer objects.
   * encoding: 'utf8'
   * }
   * @return {Comsumer} instance - Async
   */
  function comsumer(payloads, option) {
    return Comsumer(clients, payloads, option);
  }

  const object = {
    clients,
    producer,
    highLevelProducer,
    comsumer };

  return object;
}