Trigger Lambda function with SQS Queue as trigger

dispatcher.js

"use strict";

const AWS_REGION = process.env.AWS_REGION;

const Promise = require("bluebird");
const AWS = require("aws-sdk");
const eventUtils = require("./eventUtils.js");

AWS.config.update({ region: AWS_REGION });
AWS.config.setPromisesDependency(Promise);

class Dispatcher {
  constructor() {
    this.PUBLISHED_QUEUE_URL = process.env.PUBLISHED_QUEUE_URL;
    this.AWS_ACCOUNTID = process.env.AWS_ACCOUNTID;
    this.sns = undefined;
    this.sqs = undefined;
  }

  init() {
    this.sns = new AWS.SNS();
    this.sqs = new AWS.SQS();
  }

  //--------------------------------------------------------
  // --- Dispatches the event to the topic corresponding to it's type
  //--------------------------------------------------------
  dispatchEvent(event, topic) {
    var params = {
      TopicArn:
        "arn:aws:sns:" + AWS_REGION + ":" + this.AWS_ACCOUNTID + ":" + topic,
      Subject: event.eventType,
      Message: eventUtils.stringify(event)
    };
    return this.sns.publish(params).promise();
  }

  //--------------------------------------------------------
  // --- Dispatches all the events
  //--------------------------------------------------------
  dispatchAll(events) {
    return Promise.all(
      events.map(() => this.dispatchEvent(event, event.eventType))
    );
  }
}

exports.Dispatcher = Dispatcher;

//----------------------------
// --- Handles the incoming event from SQS
//----------------------------
exports.handler = function(sqsEvent, context, callback) {
  let dispatcher = new Dispatcher();
  dispatcher.init();
  const events = sqsEvent.Records.filter(event =>
    eventUtils.getOriginal(JSON.parse(event.body))
  );

  dispatcher
    .dispatchAll(events)
    .then(data => {
      callback(undefined, data);
    })
    .catch(callback);
};