Book Image

Mastering Ansible, 4th Edition - Fourth Edition

By : James Freeman, Jesse Keating
Book Image

Mastering Ansible, 4th Edition - Fourth Edition

By: James Freeman, Jesse Keating

Overview of this book

Ansible is a modern, YAML-based automation tool (built on top of Python, one of the world’s most popular programming languages) with a massive and ever-growing user base. Its popularity and Python underpinnings make it essential learning for all in the DevOps space. This fourth edition of Mastering Ansible provides complete coverage of Ansible automation, from the design and architecture of the tool and basic automation with playbooks to writing and debugging your own Python-based extensions. You'll learn how to build automation workflows with Ansible’s extensive built-in library of collections, modules, and plugins. You'll then look at extending the modules and plugins with Python-based code and even build your own collections — ultimately learning how to give back to the Ansible community. By the end of this Ansible book, you'll be confident in all aspects of Ansible automation, from the fundamentals of playbook design to getting under the hood and extending and adapting Ansible to solve new automation challenges.
Table of Contents (18 chapters)
Section 1: Ansible Overview and Fundamentals
Section 2: Writing and Troubleshooting Ansible Playbooks
Section 3: Orchestration with Ansible

Variable introspection

A common set of problems that are encountered when developing Ansible playbooks is the improper use, or invalid assumption, of the value of variables. This is particularly common when registering the results of one task in a variable, and later using that variable in a task or template. If the desired element of the result is not accessed properly, the end result will be unexpected, or perhaps even harmful.

To troubleshoot improper variable usage, an inspection of the variable value is the key. The easiest way to inspect a variable's value is with the ansible.builtin.debug module. The ansible.builtin.debug module allows the display of freeform text on screen, and as with other tasks, the arguments to the module can take advantage of the Jinja2 template syntax as well. Let's demonstrate this usage by creating a sample play that executes a task, registers the result, and then shows the result in an ansible.builtin.debug statement using...