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)

Handling multiline with HEREDOC

Writing multiline file fragments in Puppet mostly resulted in code that was hard to read, mostly due to indentation. With Puppet 4, the heredoc style was added. It is now possible to specify a heredoc tag and marker:

$motd_content = @(EOF) 
  This system is managed by Puppet 
  local changes will be overwritten by next Puppet run. 

The heredoc tag starts with an @ sign followed by arbitrary string enclosed in parenthesis. The heredoc marker is the string given in the tag.

If variables are required inside the heredoc document, the variable interpolation can be enabled by putting the tag string in double quotes. Variables inside the heredoc are written the same as Puppet DSL variables: a dollar sign followed by the scope and the variable name:

$motd_content = @("EOF") 
  Welcome to ${::fqdn}. 
  This system is managed by Puppet version...