Infrastructure as Code, 2nd Edition

Chapter 2. Principles of Cloud Age Infrastructure

Computing resources in the Iron Age of IT were tightly coupled to physical hardware. We assembled CPUs, memory, and hard drives in a case, mounted it into a rack, and cabled it to switches and routers. We installed and configured an operating system and application software. We could describe where an application server was in the data center: which floor, which row, which rack, which slot.

The Cloud Age decouples the computing resources from the physical hardware they run on. The hardware still exists, of course, but servers, hard drives, and routers float across it. These are no longer physical things, having transformed into virtual constructs that we create, duplicate, change, and destroy at will.

This transformation has forced us to change how we think about, design, and use computing resources. We can’t rely on the physical attributes of our application server to be constant. We must be able to add and remove instances of our systems without ceremony, and we need to be able to easily maintain the consistency and quality of our systems even as we rapidly expand their scale.

There are several principles for designing and implementing infrastructure on cloud platforms. These principles articulate the reasoning for using the three core practices (define everything as code, continuously test and deliver, build small pieces). I also list several common pitfalls that teams make with dynamic infrastructure.

These principles and pitfalls ...