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

Managing users with virtual resources


Users are a great example of a resource that may need to be realized by multiple classes. Consider the following situation. To simplify the administration of a large number of machines, you defined classes for two kinds of user: developers and sysadmins. All machines need to include sysadmins, but only some machines need access to developers:

node 'server' {
  include user::sysadmins
}
node 'webserver' {
  include user::sysadmins
  include user::developers
}

However, some users may be members of both groups. If each group simply declares its members as regular user resources, this will lead to a conflict when a node includes both developers and sysadmins, as in the webserver example.

To avoid this conflict, a common pattern is to make all users virtual resources, defined in a single user::virtual class that every machine includes, and then realize the users where they are needed. This way, there will be no conflict if a user is a member of multiple groups...