Copy S3 data to DynamoDB

gistfile1.js

let path = require('path');
let aws = require('aws-sdk');
let s3 = new aws.S3();
let zlib = require('zlib');
let docClient = new aws.DynamoDB.DocumentClient();

exports.handler = (event, context, callback) => {
    context.callbackWaitsForEmptyEventLoop = false;

    event.Records.forEach(record => {
        const params = {
            Bucket: record.s3.bucket.name,
            Key: record.s3.object.key
        };

        const isGzip = path.extname(params.Key) === ".gz";
        let readStream = s3.getObject(params).createReadStream();

        readStream = isGzip ? readStream.pipe(zlib.createGunzip()) : readStream;
        readStream.on('data', data => {
            // transform to string
            // seperate lines, remember that the first / last lines could be partial of the previous / next 'data' event

            const dynamoDbDocument = {
                // csv parse each line
            };

            const dynamoDbParams = {
                TableName: "Table Name",
                Item: dynamoDbDocument
            };

            docClient.put(params, function (err, data) {
                if (err) {
                    console.error("Unable to add item. Error JSON:", JSON.stringify(err, null, 2));
                } else {
                    console.log("Added item:", JSON.stringify(data, null, 2));
                }
            });
        });

        readStream.on('end', () => {
            // there are several IO operations that need to occur before calling this callback
            // ending the execution this way will not work.
            // use promises and wait on all of them before ending the execution
            callback(null, '');
        });
    });
};