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

Creating custom functions


If you've read the Using GnuPG to encrypt secrets recipe in Chapter 4, Working with Files and Packages, then you've already seen an example of a custom function (in that example, we created a secret function that shelled out to GnuPG). Let's look at custom functions in a little more detail now and build an example. There are two Ruby APIs available when writing custom functions, the legacy and the modern API. Legacy functions are instantiated with Puppet::Parser::Functions, modern functions are instantiated with  Puppet::Functions.create_function. In our example, we will use the modern API.

How to do it...

If you've read the Efficiently distributing cron jobs recipe in Chapter 5, Users and Virtual Resources, you might remember that we used the inline_epp function to set a random time for cron jobs to run, based on the hostname of the node. In this example, we'll take that idea and turn it into a custom function called random_minute:

  1. Create the modules/cookbook/lib...