Drupal load testing with Elastic Beanstalk, Locust and CasperJS

As Drupal becomes an ever larger mainstay in the Enterprise world of Internet websites and applications, it becomes more important for developers to test their work's ability to scale. While a piece of functionality may work perfectly fine with 5, or even 50, concurrent users, how does it work with 200? 500? 1000? Past Drupal itself, do the other pieces of the infrastructure such a MySQL, Redis, Varnish or other services keep up as the user requests pile up?

To answer these questions and more has moved well past the abilities of older load testing solutions. Apache Bench is fantastic, for example, but it doesn't parse a page, gather information, and act accordingly. It can't mimic a user working through a shopping cart, nor peruse all the mystery books on an online bookstore. After several years of in the trenches load testing it's been both my pain and pleasure to have worked through many different solutions as I've tried to find the One Load Testing Framework To Rule Them All. While the magic solution has yet to present itself, I've found a pretty good combination:

Elastic Beanstalk + Locust + CasperJS = A highly scalable, fairly easy to set up, functional open source load testing framework that meets 95% of may daily needs.

In this talk I will introduce the moving parts and walk through one of our more common load testing scenarios: A Drupal Commerce site. I will create the tests, run them, and go through the results to see where our bottlenecks are. Hopefully in doing so we can shed some light on how to test not only your code, but the other parts of your Drupal architecture.