Configuration management (CM) tools are the modern, sensible way to manage infrastructure as code. There are many such tools available, all of which operate more or less the same way: you specify your desired configuration state, using editable text files and a model of the system's resources, and the tool compares the current state of each node (the term we use for configuration-managed servers) with your desired state and makes any changes necessary to bring it in line.

As with most unimportant things, there is a great deal of discussion and argument on the Internet about which CM tool is the best. While there are significant differences in approaches and capabilities between different tools, don't let that obscure the fact that using a tool of any sort to manage configuration is much better than trying to do it by hand.

That said, while there are many CM tools available, Puppet is an excellent choice. No other tool is more powerful, more portable, or more widely adopted. In this book, I'm going to show you what makes Puppet so good and the things that only Puppet can do.