Book Image

Chef Cookbook - Third Edition

By : Matthias Marschall
Book Image

Chef Cookbook - Third Edition

By: Matthias Marschall

Overview of this book

Chef is a configuration management tool that lets you automate your more cumbersome IT infrastructure processes and control a large network of computers (and virtual machines) from one master server. This book will help you solve everyday problems with your IT infrastructure with Chef. It will start with recipes that show you how to effectively manage your infrastructure and solve problems with users, applications, and automation. You will then come across a new testing framework, InSpec, to test any node in your infrastructure. Further on, you will learn to customize plugins and write cross-platform cookbooks depending on the platform. You will also install packages from a third-party repository and learn how to manage users and applications. Toward the end, you will build high-availability services and explore what Habitat is and how you can implement it.
Table of Contents (15 chapters)
Chef Cookbook - Third Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Using pure Ruby in templates for conditionals and iterations


Switching options on and off in a configuration file is a pretty common thing. Since Chef uses ERB as its template language, you can use pure Ruby to control the flow in your templates. You can use conditionals or even loops in your templates.

Getting ready

Make sure that you have a cookbook called my_cookbook and that the run_list of your node includes my_cookbook, as described in the Creating and using cookbooks recipe in Chapter 1, Chef Infrastructure.

How to do it…

Let's create a hypothetical configuration file listing the IP addresses of a given set of backend servers. We only want to print that list if the flag called enabled is set to true:

  1. Edit your cookbook's default recipe:

    mma@laptop:~/chef-repo $ subl cookbooks/my_cookbook/recipes/default.rb
    template "/tmp/backends.conf" do
      mode "0444"
      owner "root"
      group "root"
      variables({
        :enabled => true,
        :backends => ["10.0.0.10", "10.0.0.11", "10.0.0.12"]
      })
    end...