Book Image

Chef Essentials

By : John Ewart
Book Image

Chef Essentials

By: John Ewart

Overview of this book

<p>Chef is a configuration management tool that turns IT infrastructure into code. Chef provides tools to manage systems at scale. With this book, you will learn how to use the same tools that companies such as Facebook, Riot Games, and Ancestry.com use to manage and scale their infrastructure.</p> <p>This book takes you on a comprehensive tour of Chef's functionality, ranging from its core features to advanced development. You will be brought up to speed with what's new in Chef and how to set up your own Chef infrastructure for individuals, or small or large teams. Once you have the core components, you will get to grips with bootstrapping hosts to then develop and apply cookbooks. If you want to fully leverage Chef, this book will show you advanced recipes to help you handle new types of data providers and resources. By the end of this book, you will be confident in how to manage your infrastructure, scale using the cloud, and extend the built-in functionality of Chef itself.</p>
Table of Contents (15 chapters)
Chef Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Templates


Chef dynamically configures software and hosts, and a large part of configuring UNIX-based systems and software involves configuration files. Chef provides a straightforward mechanism to generate configuration files that make it easy to combine configuration data with template files to produce the final configuration files on hosts. These templates are stored in the templates directory inside of a cookbook and use the ERB template language, which is a popular and easy-to-use Ruby-based template language.

Why use templates?

Without templates, your mechanism to generate configuration files would probably look something like this:

File.open(local_filename, 'w') do |f| 
  f.write("<VirtualHost *:#{node['app]['port']}")
  ...
  f.write("</VirtualHost>")
end

This should be avoided for a number of reasons. First, writing configuration data this way would most likely make your recipe very cluttered and lengthy. Secondly, and more importantly, it violates Chef's declarative nature...