Preface

A revolution is underway in the field of IT operations. The new generation of configuration management tools can build servers in seconds and automate your entire network. Tools such as Puppet are essential to take full advantage of the power of cloud computing, and build reliable, scalable, secure, high-performance systems.

This book takes you beyond the basics and explores 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 complete code samples for every recipe.

It takes the reader from rudimentary knowledge of Puppet to a more complete and expert understanding of Puppet's latest and most advanced features, community best practices, writing great manifests, scaling and performance, and how to extend Puppet by adding your own providers and resources.

This book also includes real examples from production systems and techniques that are in use in some of the world's largest Puppet installations. It will show you different ways to do things using Puppet and point out some of the pros and cons of these approaches.

The book is structured so that you can dip in at any point and try out a recipe without having to work your way through from cover to cover. You'll find links and references to more information on every topic, so that you can explore further for yourself. Whatever your level of Puppet experience, there's something for you, from simple workflow tips to advanced, high-performance Puppet architectures.

I've tried hard to write the kind of book that would be useful to me in my day-to-day work as a devops consultant. I hope it will inspire you to learn, to experiment, and to come up with your own new ideas in this exciting and fast-moving field.

What this book covers

You'll find the following chapters in this book:

Chapter 1, Puppet Infrastructure, shows how to set up Puppet for the first time, including instructions on installing Puppet, creating your first manifests, using version control with Puppet, building a distributed Puppet architecture based on Git, writing a script to apply Puppet manifests, running Puppet automatically, using Rake to bootstrap machines and deploy changes, and using Git hooks to automatically syntax-check your manifests.

Chapter 2, Puppet Language and Style, covers aspects of writing good Puppet code, including using Puppet community style, checking your manifests with puppet-lint, structuring your manifests with modules, using standard naming and style conventions, using inline templates, using iteration, conditional statements, and regular expressions, using selectors and case statements, and string operations.

Chapter 3, Writing Better Manifests, goes into detail on specific features of Puppet that you can use to improve your code quality and usability, including arrays, definitions, ordering your resources with dependencies, inheriting from nodes and classes, passing parameters to classes, overriding parameters, reading information from the environment, writing reusable manifests, and using tags and run stages.

Chapter 4, Working with Files and Packages, deals with some of the most common sysadmin tasks, including managing config files, using Augeas, generating files from snippets and templates, managing third-party package repositories, using GnuPG to encrypt secret data in Puppet, and building packages from source.

Chapter 5, Users and Virtual Resources, explains what virtual resources are and how they can help you manage different combinations of users and packages on different machines, and shows you how to use Puppet's resource scheduling and auditing features.

Chapter 6, Applications, focuses on some specific applications that you may need to manage with Puppet, including complete recipes for Apache and Nginx, MySQL, and Ruby.

Chapter 7, Servers and Cloud Infrastructure, extends the power of Puppet to manage virtual machines, both on the cloud and on your desktop, with recipes for Vagrant and EC2 instances. It also shows you how to set up load balancing with HAProxy, firewalls with iptables, network filesystems with NFS, and high-availability services with Heartbeat.

Chapter 8, External Tools and the Puppet Ecosystem, looks at some of the tools that have grown up around Puppet, including Hiera, Facter, and rspec-puppet. It also introduces you to some advanced topics including writing your own resource types, providers, and external node classifiers.

Chapter 9, Monitoring, Reporting, and Troubleshooting, covers ways that Puppet can report information about what it's doing, and the status of your system. This includes reports, log, and debug messages, dependency graphing, testing and dry-running your manifests, and a guide to some of Puppet's more common error messages.

What you need for this book

To run the examples in this book, you will need a computer with Ubuntu Linux 12.04 and an Internet connection.

Who this book is for

The book assumes that the reader has a little experience of Linux systems administration, including familiarity with the command line, file system, and text editing. No programming experience is required.

Conventions

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "You can check your manifests for style guide compliance using the puppet-lint tool."

A block of code is set as follows:

node 'cookbook' {
  cron { 'randomised cron job':
    command => '/bin/echo Hello, world >>/tmp/hello.txt',
    hour    => '*',
    minute  => random_minute(),
  }
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

newparam(:path) do
  validate do |value|
    basepath = File.dirname(value)
    unless File.directory?(basepath)
      raise ArgumentError , "The path %s doesn't exist" % basepath
    end
  end
end

Any command-line input or output is written as follows:

ubuntu@cookbook:~/puppet$ papply
Notice: Hello, I was included by your ENC!
Notice: /Stage[main]/Admin::Helloenc/Notify[Hello, I was included by your ENC!]/message: defined 'message' as 'Hello, I was included by your ENC!'
Notice: Finished catalog run in 0.29 seconds

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "clicking the Next button moves you to the next screen".

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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