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

Noop—the don't-change-anything option


Sometimes, your Puppet manifest doesn't do exactly what you expected, or perhaps someone else has checked in changes you didn't know about. Either way, it's good to know exactly what Puppet is going to do before it does it.

When you are retrofitting Puppet into an existing infrastructure, you might not know whether Puppet is going to update a config file or restart a production service. Any such change could result in unplanned downtime. Also, sometimes, manual configuration changes are made on a server that Puppet would overwrite.

To avoid these problems, you can use Puppet's noop mode, which means

no operation

or do nothing. When run with the noop option, Puppet only reports what it would do, but doesn't actually do anything. One caveat here is that even during a noop run, pluginsync still runs and any lib directories in modules will be synced to nodes. This will update external fact definitions and possibly Puppet's types and providers. If you are using...