Systems administrators have probably been writing scripts and tools to make their jobs easier since day one. When I joined my first systems team, the mantra “let the machines do the boring work” was drilled into my head. The popularization of cloud (IaaS) and virtualized infrastructure over the past decade has given us the opportunity to automate the boring work in some very different, and cool ways.

We have moved from the Iron Age of infrastructure and into the Cloud Era. The resources of an IT infrastructure - compute, storage, and networking - have been transmogrified from inflexible physical hardware into dynamic software and data. In the Iron Age, the interface for creating a new server was a purchasing request form. In the Cloud Era, it’s a programmable API.

So. If our infrastructure is now software and data, manageable through an API, then this means we can bring tools and ways of working from software engineering and use them to manage our infrastructure. This is the essence of Infrastructure as Code.

In software engineering we write code, keep it in a Version Control System (VCS) and automatically test it with Continuous Integration (CI). We and deploy it to a series of environments using a Deployment Pipeline so it can be validated before putting it into production use. Now we can easily do the same with infrastructure.

Infrastructure as Code doesn’t only apply to cloud and virtualized infrastructures, it can also be used with “bare metal” infrastructure. I’ve worked with teams who’ve implemented dynamic hardware system management. We used Cobbler to automatically install servers using PXE-boot installation over a network. When we implemented this we had to start the installation at the physical server (boot the server and hold down F12, in our case). But many hardware vendors have Lights Out Management functionality that makes it possible to do this remotely, and even automatically.

I’ve run across many teams who are in the same place I was a few years ago, people who are using cloud, virtualization, and automation tools, but haven’t got it all running as smoothly as they know they could.

Much of the challenge is time. Day to day life for systems administrators is coping with a never-ending flow of critical work. Fighting fires, fixing problems, and setting up new business critical projects doesn’t leave much time to work on the fundamental improvements that will make the routine work easier.

My hope is that this book provides a practical vision for how to manage IT infrastructure, with techniques and patterns that teams can try and use. I will avoid the details of configuring and using specific tools, so that the content will be useful for working with different tools, including ones that may not exist yet. On the other hand, I will use examples from current tools to illustrate the point I make.

The Infrastructure as Code approach is essential for managing cloud infrastructure of any real scale or complexity, but they’re not exclusive to organizations using public cloud providers. The techniques and practices in this book have proven effective in virtualized environments, and even without any virtualization.