Netflix is a high-profile consumer service. When things go wrong, people tend to notice. So it might seem strange that the company tries to make things go wrong with its service on a regular basis.
That's indeed the goal of "Chaos Monkey," the automated software Netflix developed to test its infrastructure's mettle. In layman's terms, Chaos Money tries to break stuff. The theory behind this is to build a stronger platform and avoid the types of major, unexpected problems that tend to make IT's phones ring at 2 a.m. (Netflix configures the tool to run only during normal business hours; that way IT staff handle any related issues during the day instead of on nights and weekends.)
Now everyone can embrace the chaos: Netflix just made the source code publicly available as a free download. You'll first need to ask yourself if you've got the guts for it. Or, as Netflix put it in a blog post: "Do you think your applications can handle a troop of mischievous monkeys loose in your infrastructure?"
[ Security researcher Dan Kaminsky wants to address security by changing the fundamental way code is written. Read more at Tired Of Security Problems? Change Rules Of Writing Code. ]
If you're picturing the band of winged monkeys from "The Wizard of Oz" running amok, you're not far off--they've just been reengineered for the cloud. Chaos Monkey deliberately shut downs virtual machines (VMs) within Amazon's Auto-Scaling Groups (ASGs). (Though the software was written with Amazon Web Services in mind, Netflix said Chaos Monkey is flexible enough to work with other cloud platforms.)
By causing intentional failures on individual instances--Netflix generated more than 65,000 failures in the last year, according to the company--you can learn from those errors and their resolutions. Basic example: Is your application hardy enough to weather a failed VM, or could that single instance bring the curtains down on the whole show?
That type of no-holds-barred testing can help unearth and resolve unknown issues before they become major outages. Better yet, it can lead to stronger applications as they're being built, rather than trying to retrofit them after the fact. "By having that constant idea that something's going to break, [Netflix has] within their dev ops and engineering departments the mindset that they have to make sure that no single point can take down the entire site," said Jim MacLeod, product manager at the networking firm WildPackets, in an interview.
In Netflix's case, it makes sense to try to rise to Chaos Monkey's challenge--their bottom line depends upon their site running smoothly. "If you look at Netflix's business model, what really differentiates them isn't just streaming media--it's the fact there's something immediate and easy for users to get to, but that means they have to be fairly reliable," MacLeod said. "Reliability and uptime are things that are difficult to put in afterwards if you don't design it in, just like security."