Book Image

Ansible Playbook Essentials

By : Gourav Shah, GOURAV JAWAHAR SHAH
Book Image

Ansible Playbook Essentials

By: Gourav Shah, GOURAV JAWAHAR SHAH

Overview of this book

Ansible Playbook Essentials will show you how to write a blueprint of your infrastructure, encompassing multitier applications using Ansible's playbooks. Beginning with basic concepts such as plays, tasks, handlers, inventory, and YAML Ain't Markup Language (YAML) syntax that Ansible uses, you'll understand how to organize your code into a modular structure. Building on this, you will study techniques to create data-driven playbooks with variables, templates, logical constructs, and encrypted data, which will further strengthen your application skills in Ansible. Adding to this, the book will also take you through advanced clustering concepts, such as discovering topology information about other nodes in the cluster and managing multiple environments with isolated configurations. As you approach the concluding chapters, you can expect to learn about orchestrating infrastructure and deploying applications in a coordinated manner. By the end of this book, you will be able to design solutions to your automation and orchestration problems using playbooks quickly and efficiently.
Table of Contents (20 chapters)
Ansible Playbook Essentials
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Setting Up the Learning Environment
References
Index

Chapter 7. Node Discovery and Clustering

For most real-world scenarios, we would need to create a cluster of compute nodes with the applications running on top, which are linked together. For example, the WordPress site that we have been building requires web servers and databases connected together.

Clustered infrastructure has a topology where one class of nodes should be able to discover information about the different, or the same, class of servers. For example, the WordPress application servers need to discover information about database servers, and load balancers need to know about the IP address/hostname of each web server that it's serving traffic to. This chapter focuses on what primitives Ansible offers to group together nodes and discover the attributes of interconnected nodes.

In this chapter, we will learn about:

  • Discovering information about other nodes in the cluster

  • Generating configurations dynamically using the magic variables discovered

  • Why and how to enable fact caching