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

Working with the cli_command module

Before we get to the practical hands-on examples, we must look at a module that has become central to network device configuration since the previous edition of this book was published.

As we discussed in the preceding section, most network devices cannot be expected to have a working Python environment on them, and as such, Ansible will use local execution – that is to say, all tasks related to network devices are executed on the Ansible control node itself, translated into the correct format for the device to receive (be that a CLI, an HTTP-based API, or otherwise), and then sent over the network to the device. Ansible 2.7 relied mostly on a communication protocol known as local for network device automation. This worked well but suffered from several drawbacks, including the following:

  • The local protocol does not support persistent network connections – a new connection needs to be set up and then torn down for each task...