Book Image

Puppet 5 Essentials - Third Edition

By : Martin Alfke, Felix Frank
Book Image

Puppet 5 Essentials - Third Edition

By: Martin Alfke, Felix Frank

Overview of this book

Puppet is a configuration management tool that allows you to automate all your IT configurations, giving you control over what you do to each Puppet Agent in a network, and when and how you do it. In this age of digital delivery and ubiquitous Internet presence, it's becoming increasingly important to implement scaleable and portable solutions, not only in terms of software, but also the system that runs it. This book gets you started quickly with Puppet and its tools in the right way. It highlights improvements in Puppet and provides solutions for upgrading. It starts with a quick introduction to Puppet in order to quickly get your IT automation platform in place. Then you learn about the Puppet Agent and its installation and configuration along with Puppet Server and its scaling options. The book adopts an innovative structure and approach, and Puppet is explained with flexible use cases that empower you to manage complex infrastructures easily. Finally, the book will take readers through Puppet and its companion tools such as Facter, Hiera, and R10k and how to make use of tool chains.
Table of Contents (10 chapters)

Creating Puppet 4 functions

The Puppet 3 functions API has some limitations and is missing features. The new function API in Puppet 4 improves upon that substantially.

Some of the limitations of the old functions are as follows:

  • The functions had no automatic type checking
  • These functions had to have a unique name due to a flat namespace
  • These functions were not private and, hence, could be used anywhere
  • The documentation could not be retrieved without running the Ruby code

Running on Puppet 3 requires functions to be in a module in the lib/puppet/parser/functions directory. Therefore, people referred to these functions as parser functions, but this name is misleading. Functions are unrelated to the Puppet parser.

In Puppet 4, functions have to be put into a module in path lib/puppet/functions.

This is how you create a function that will return the hostname of the Puppet master...