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

Making recipes idempotent by using conditional execution


Chef manages the configuration of your nodes. It is not simply an installer for new software but you will run the Chef client on the existing nodes, as well as new ones.

To speed up your Chef client runs on the existing nodes, you should make sure that your recipes do not try to re-execute resources that have already reached the desired state.

Running resources repeatedly will be a performance issue at best and will break your servers at worst. Chef offers a way to tell resources not to run or only to run if a certain condition is met. Let's look at how conditional execution of resources works.

Getting ready

Make sure 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 see how to use conditional execution in our cookbooks:

  1. Edit your default recipe to trigger a callback only if you have...