Learning CFEngine 3: Automated system administration for sites of any size (Repost)

CFEngine is the most mature and widely used tool for comprehensive configuration management. This book is devoted to CFEngine 3, released in 2009. The main audience for this book is experienced system administrators of null-to-medium expertise with CFEngine, although more advanced CFEngine users may also find useful snippets and techniques. Its goal is to guide you from installation to advanced examples and concepts by using examples and techniques that can be put to work straight away. CFEngine was first released in 1993, and it has evolved over the years to address real needs in real systems, and to match the technological evolutions that have taken place, such as virtualization and cloud computing. CFEngine is fine-tuned to the features and design that make it possible to automate very large numbers of systems in a scalable and manageable way. CFEngine has been designed to be very resource-efficient, and it can run on everything from smartphones to supercomputers. With the new version came a complete overhaul of its syntax and mode of operation, and with many new features such as Knowledge Management and support for virtual environments. CFEngine 3 is different from many other automation mechanisms in that you do not need to tell it what to do. Instead, you specify the state in which you wish the system to be, and CFEngine will automatically and iteratively decide the actions to take to reach the desired state, or as close to it as possible. Underlying this ability is a powerful theoretical model known as Promise Theory, which was initially developed for CFEngine 3, but which has also found other applications in Computer Science and in other fields such as Economics and Organization.