AWS Lambda saveWeekenderDataToS3()

index.js

const AWS = require('aws-sdk');
const http = require('http');

const BUCKET_ID = 'weekender-data';
const FILES = {
    'weekendstatus.js': 'http://web.mta.info/status/weekendstatus.js',
    'weekendroutestatus.js': 'http://web.mta.info/status/weekendroutestatus.js',
    'weekendboroughstatus.js': 'http://web.mta.info/status/weekendboroughstatus.js',
    'LinesStaticData.js': 'http://web.mta.info/weekender/Data/LinesStaticData.js'
};

exports.handler = async (event) => {
    const responses = await getAll(FILES);
    return responses;
};

function getAll (obj) {
    return Promise.all(Object.entries(obj).map(getAndSaveToS3));
}

async function getAndSaveToS3 ([key, url] = entry) {
    const response = await getContent(url);
    const etag = await putObjectToS3(BUCKET_ID, key, response);
    return etag;
}

function getContent (url) {
    // return new pending promise
    return new Promise((resolve, reject) => {
        // select http or https module, depending on reqested url
        // const lib = url.startsWith('https') ? require('https') : require('http');
        const request = http.get(url, (response) => {
            // handle http errors
            if (response.statusCode < 200 || response.statusCode > 299) {
                reject(new Error('Failed to load page, status code: ' + response.statusCode));
            }
            // temporary data holder
            const body = [];
            // on every content chunk, push it to the data array
            response.on('data', (chunk) => body.push(chunk));
            // we are done, resolve promise with those joined chunks
            response.on('end', () => resolve(body.join('')));
        });
        // handle connection errors of the request
        request.on('error', (err) => reject(err));
    });
}

function putObjectToS3 (bucket, key, data) {
    // return new pending promise
    return new Promise((resolve, reject) => {
        const s3 = new AWS.S3();
        const params = {
            Bucket: bucket,
            Key: key,
            Body: data,
            ACL: 'public-read' // Make sure IAM role has S3:PutObjectACL permissions set
        };

        s3.putObject(params, function (err, data) {
            if (err) {
                reject(new Error(err));
            } else {
                resolve(data);
            }
        });
    });
}