Chaos Monkey

Chaos Monkey is a tool invented in 2011 by Netflix to test the resilience of its IT infrastructure. It works by intentionally disabling computers in Netflix's production network to test how remaining systems respond to the outage. Chaos Monkey is now part of a larger suite of tools called the Simian Army designed to simulate and test responses to various system failures and edge cases.

The code behind Chaos Monkey was released by Netflix in 2012 under an Apache 2.0 license.

The name "Chaos Monkey" is explained in the book Chaos Monkeys by Antonio Garcia Martinez.

"Imagine a monkey entering a 'data center', these 'farms' of servers that host all the critical functions of our online activities. The monkey randomly rips cables, destroys devices and returns everything that passes by the hand. The challenge for IT managers is to design the information system they are responsible for so that it can work despite these monkeys, which no one ever knows when they arrive and what they will destroy."

The Simian Army is a suite of tools developed by Netflix to test the reliability, security, or resiliency of its Amazon Web Services infrastructure and includes the following tools.

At the very top of the Simian Army hierarchy, Chaos Kong drops a full AWS "Region". Though rare, loss of an entire region does happen and Chaos Kong simulates a systems response and recovery to this type of event.

Chaos Gorilla drops a full Amazon "Availability Zone" (one or more entire data centers serving a geographical region).