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

In-place upgrades

The first type of deployment that we'll cover is in-place upgrades. This style of deployment operates on an infrastructure that already exists, in order to upgrade the existing application. This model is a traditional model that was used when the creation of new infrastructure was a costly endeavor, in terms of both time and money.

A general design pattern to minimize the downtime during this type of upgrade is to deploy the application across multiple hosts, behind a load balancer. The load balancer will act as a gateway between users of the application and the servers that run the application. Requests for the application will come to the load balancer, and, depending on the configuration, the load balancer will decide which backend server to direct the requests to.

To perform a rolling in-place upgrade of an application deployed with this pattern, each server (or a small subset of the servers) will be disabled at the load balancer, upgraded...