handler.js

'use strict';

const request = require('request');

/**
 * Use this command to launch the handler from console:
 *
 * node_modules/.bin/serverless invoke local -f lambda -d '{"httpMethod":"GET","queryStringParameters":{"url":"http://github.com"}}'
 *
 *  or from browser
 *
 * http://localhost:3000/?url=https://github.com
 */
module.exports.corsProxy = (event, context, callback) => {
    let params = event.queryStringParameters;

    console.log(event);
    console.log(`Got request with params:`, params);

    if (!params.url) {
        const errorResponse = {
            statusCode: 400,
            body: 'Unable get url from \'url\' query parameter'
        };

        callback(null, errorResponse);

        return;
    }

    return new Promise((resolve, reject) => {
        request({
            url: params.url,
            method: event.httpMethod,
            timeout: 20000
        }, (err, originalResponse) => {
            if (err) {
                console.log(`Got error`, err);

                callback(err);

                reject(err);

                return;
            }

            console.log(`Got response from ${params.url} ---> {statusCode: ${originalResponse.statusCode}}`);

            const proxyResponse = {
                statusCode: originalResponse.statusCode,
                headers: {
                    "Access-Control-Allow-Origin" : "*", // Required for CORS support to work
                    "Access-Control-Allow-Credentials" : true, // Required for cookies, authorization headers with HTTPS
                    "content-type": originalResponse.headers['content-type']
                },
                body: originalResponse.body
            };

            callback(null, proxyResponse);

            resolve(proxyResponse);
        });
    });
};