Book Image

Practical Ansible - Second Edition

By : James Freeman, Fabio Alessandro Locati, Daniel Oh
Book Image

Practical Ansible - Second Edition

By: James Freeman, Fabio Alessandro Locati, Daniel Oh

Overview of this book

Ansible empowers you to automate a myriad of tasks, including software provisioning, configuration management, infrastructure deployment, and application rollouts. It can be used as a deployment tool as well as an orchestration tool. While Ansible provides simple yet powerful features to automate multi-layer environments using agentless communication, it can also solve other critical IT challenges, such as ensuring continuous integration and continuous deployment (CI/CD) with zero downtime. In this book, you'll work with the latest release of Ansible and learn how to solve complex issues quickly with the help of task-oriented scenarios. You'll start by installing and configuring Ansible on Linux and macOS to automate monotonous and repetitive IT tasks and learn concepts such as playbooks, inventories, and roles. As you progress, you'll gain insight into the YAML syntax and learn how to port between Ansible versions. Additionally, you'll understand how Ansible enables you to orchestrate multi-layer environments such as networks, containers, and the cloud. By the end of this Ansible book, you'll be well versed in writing playbooks and other related Ansible code to overcome all your IT challenges, from infrastructure-as-a-code provisioning to application deployments and handling mundane day-to-day maintenance tasks.
Table of Contents (21 chapters)
Free Chapter
1
Part 1:Learning the Fundamentals of Ansible
6
Part 2:Expanding the Capabilities of Ansible
12
Part 3:Using Ansible in an Enterprise

Asynchronous versus synchronous actions

As we have seen in this book so far, Ansible plays are executed in sequence, with each task running to completion before the next task is started. Although this is often advantageous for flow control and logical sequencing, there are times when you may not want this. In particular, it might be the case that a particular task runs for longer than the configured SSH connection timeout, and as Ansible uses SSH to perform its automation tasks on most platforms, this would be an issue.

Fortunately, Ansible tasks can be run asynchronously—that is to say, tasks can be run in the background on the target host and polled on a regular basis. This is in contrast to synchronous tasks, where the connection to the target host is kept open until the task completes (which runs the risk of a timeout occurring).

As ever, let’s explore this through a practical example. Suppose we have two servers in a simple INI-formatted inventory:

[frontends...