Modern distributed systems have aggressive requirements around uptime and performance, they need to face harsh realities such as sudden rush of visitors, network issues, tangled databases and other unforeseen bugs. With so many moving parts involved even in the simplest of services, it becomes mandatory to adopt defensive patterns which would guard against some of these problems and identify anti-patterns before they trigger cascading failures across systems. This talk is for all those developers who hate getting a oncall at 4 AM in the morning.