Book Image

Puppet 3 Cookbook - Second Edition

By : John Arundel
Book Image

Puppet 3 Cookbook - Second Edition

By: John Arundel

Overview of this book

A revolution is happening in web operations. Configuration management tools can build servers in seconds, and automate your entire network. Tools like Puppet are essential to taking full advantage of the power of cloud computing, and building reliable, scalable, secure, high-performance systems. More and more systems administration and IT jobs require some knowledge of configuration management, and specifically Puppet."Puppet 3 Cookbook" takes you beyond the basics to explore the full power of Puppet, showing you in detail how to tackle a variety of real-world problems and applications. At every step it shows you exactly what commands you need to type, and includes full code samples for every recipe.The book takes the reader from a basic knowledge of Puppet to a complete and expert understanding of Puppet's latest and most advanced features, community best practices, writing great manifests, scaling and performance, and extending Puppet by adding your own providers and resources. It starts with guidance on how to set up and expand your Puppet infrastructure, then progresses through detailed information on the language and features, external tools, reporting, monitoring, and troubleshooting, and concludes with many specific recipes for managing popular applications.The book includes real examples from production systems and techniques that are in use in some of the world's largest Puppet installations, including a distributed Puppet architecture based on the Git version control system. You'll be introduced to powerful tools that work with Puppet such as Hiera. The book also explains managing Ruby applications and MySQL databases, building web servers, load balancers, high-availability systems with Heartbeat, and many other state-of-the-art techniques
Table of Contents (16 chapters)
Puppet 3 Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Importing configuration data with Hiera


A key principle of good programming is to separate data and code. Many Puppet manifests are full of site-specific data that makes it hard to share and re-use the manifests. Grouping all such data into structured text files and moving it outside the Puppet manifests makes it easier to maintain, as well as easier to re-use and share code with other people.

Ideally, we'd not only be able to look up configuration parameters from a data file, but also choose a different data file depending on things like the environment, the operating system, and other facts about the machine. We'd also like to be able to organize the data hierarchically so that we can override certain values with other, higher-priority values.

Puppet has a mechanism named Hiera (as in 'hierarchy') to do just this. The hiera function lets you look up configuration data from within your manifest, and Hiera takes care of returning the correct value for the current environment.

Getting ready...