My grateful thanks are due to Jo Rhett, who made innumerable improvements and suggestions to this book, and whose Puppet expertise and clarity of writing I can only strive to emulate. Also to the original Puppet master, Luke Kanies, who created a configuration management tool that sucks less, and my many other friends at Puppet. Many of the key ideas in this book came from them and others including Przemyslaw 'SoboL' Sobieski, Peter Bleeck, and Igor Galić.

The techniques and examples in the book come largely from real production codebases, of my consulting clients and others, and were developed with the indispensable assistance of my friends and colleagues Jon Larkowski, Justin Domingus, Walter Smith, Ian Shaw, and Mike Thomas. Special thanks are also due to the Perseids Project at Tufts University, and most of all to the inestimable Bridget Almas, who patiently read and tested everything in the book several times and made many valuable suggestions, not to mention providing continuous moral support, love, and guidance throughout the writing process. This book is for her.