Lambda function to synchronize no objects between two diffrent S3 Buckets

index.js

// adapted from http://docs.aws.amazon.com/lambda/latest/dg/with-s3-example-deployment-pkg.html

// dependencies
var async = require('async');
var AWS = require('aws-sdk');

// set environment vars
var DESTINATION_BUCKET = process.env.DESTINATION_BUCKET

// get reference to S3 client
var s3 = new AWS.S3();

exports.handler = function(event, context, callback) {

    if (event.Records == null) {
        context.fail('Error', "Event has no records.");
        return;
    }

    // Process all records in the event asynchronously.
    async.each(event.Records, processRecord, function (err) {
        if (err) {
            context.fail('Error', "One or more objects could not be copied.");
        } else {
            context.succeed();
        }
    });

    console.log("done")
};
function processRecord(record, callback) {
    // Read options from the event.
    var srcBucket = record.s3.bucket.name;
    // Object key may have spaces or unicode non-ASCII characters.
    var srcKey    =
    decodeURIComponent(record.s3.object.key.replace(/\+/g, " "));
    var dstBucket = DESTINATION_BUCKET;
    var dstKey    = srcKey;
    // Sanity check: validate that source and destination are different buckets.
    if (srcBucket == dstBucket) {
        callback("Source and destination buckets are the same.");
        return;
    }
    s3.copyObject({
            Bucket: dstBucket,
            CopySource: `${srcBucket}/${srcKey}`,
            Key: dstKey,
        }, function (err) {
            if (err) {
                console.error(
                    'Unable to Copy ' + srcBucket + '/' + srcKey +
                    ' and upload to ' + dstBucket + '/' + dstKey +
                    ' due to an error: ' + err
                );
                callback(err);
            } else {
                console.log(
                    'Successfully copied ' + srcBucket + '/' + srcKey +
                    ' and uploaded to ' + dstBucket + '/' + dstKey
                );
            callback();
            }
    })
}

package.json

{
  "name": "s3sync ",
  "description": "sync new s3 objects to another bucket.",
  "version": "1.0.0",
  "author": "Jonny Wheeler jonny@rentify.com",
  "license": "MIT",
  "dependencies": {
    "aws-sdk": "^2.7.9",
    "async": "^2.1.2"
  }
}

sample-policy-for-s3-syncing-role.json

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket"
            ],
            "Resource": [
                "arn:aws:s3:::EXISTING-BUCKET"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:GetObject"
            ],
            "Resource": [
                "arn:aws:s3:::EXISTING-BUCKET/*"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:ListBucket"
            ],
            "Resource": [
                "arn:aws:s3:::NEW-BUCKET"
            ]
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:PutObject"
            ],
            "Resource": [
                "arn:aws:s3:::NEW-BUCKET/*"
            ]
        }
    ]
}