Book Image

Puppet 5 Cookbook - Fourth Edition

By : Thomas Uphill
Book Image

Puppet 5 Cookbook - Fourth Edition

By: Thomas Uphill

Overview of this book

Puppet is a configuration management system that automates all your IT configurations, giving you control of managing each node. Puppet 5 Cookbook will take you through Puppet's latest and most advanced features, including Docker containers, Hiera, and AWS Cloud Orchestration. Updated with the latest advancements and best practices, this book delves into various aspects of writing good Puppet code, which includes using Puppet community style, checking your manifests with puppet-lint, and learning community best practices with an emphasis on real-world implementation. You will learn to set up, install, and create your first manifests with version control, and also learn about various sysadmin tasks, including managing configuration files, using Augeas, and generating files from snippets and templates. As the book progresses, you'll explore virtual resources and use Puppet's resource scheduling and auditing features. In the concluding chapters, you'll walk through managing applications and writing your own resource types, providers, and external node classifiers. By the end of this book, you will have learned to report, log, and debug your system.
Table of Contents (16 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Using ERB templates


While you can deploy config files easily with Puppet as simple text files, templates are much more powerful. A template file can do calculations, execute Ruby code, or reference the values of variables from your Puppet manifests. Anywhere you might deploy a text file using Puppet, you can use a template instead.

In the simplest case, a template can just be a static text file. More usefully, you can insert variables into it using the ERB (embedded Ruby) syntax. For example:

<%= @name %>, this is a very large drink.

If the template is used in a context where the variable $name contains Zaphod Beeblebrox, the template will evaluate to:

Zaphod Beeblebrox, this is a very large drink.

This simple technique is very useful for generating lots of files that only differ in the values of one or two variables, such as virtual hosts, and for inserting values into a script, such as database names and passwords.

How to do it...

In this example, we'll use an ERB template to insert a password...