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

Executing roles conditionally


The Nginx role that we created earlier to set up web server supports only Debian-based systems. Running this logic on other systems could lead to failure. For example, the Nginx role uses the apt module to install packages, which would not work on RedHat-based systems, which depend on the yum package manager. This could be avoided by adding the when statement with a fact to selectively execute based on an OS family. The following is the snippet from the www.yml playbook:

#filename: www.yml (snippet)
- hosts: www
  roles:
    - { role: nginx, when: ansible_os_family == 'Debian' }