simple lambda that sets a tracking cookie

setCookieLambda.js

'use strict';
// based on this blog post: https://aws.amazon.com/blogs/compute/simply-serverless-using-aws-lambda-to-expose-custom-cookies-with-api-gateway/
exports.handler = (event, context) => {
  let cookieKey = process.env.KEY || "wid";
  let cookieId = Math.random().toString(36).substring(6); 
  let domain = process.env.DOMAIN || "127.0.0.1:3000";
  let expires = "Fri, 31 Dec 9999 23:59:59 GMT";
  let cookieString = `${cookieKey}=${cookieId}; domain=${domain}; expires=${expires};`;
  context.done(null, {"Cookie": cookieString}); 
};