With the evolution of cloud computing, agile development methodologies, and explosion of data in recent years, there is a growing need to manage infrastructure at scale. DevOps tools and practices have become a necessity to automate every stage of such a scalable, dynamic, and complex infrastructure. Configuration management tools are at the core of this devops tool set.
Ansible is a simple, efficient, fast configuration management, orchestration and application deployment tool all combined into one. This book helps you to get familiar with writing Playbooks, Ansible's automation language. This book follows a hands-on approach to show you how to create flexible, dynamic, reusable, and data-driven roles. It then takes you through the advanced features of Ansible, such as node discovery, clustering, securing data with vault, and managing environments, and finally shows you how to use Ansible to orchestrate multitier infrastructure stack.
Chapter 1, Blueprinting Your Infrastructure, will introduced you to Playbooks, YAML, and so on. You will also learn about the components of a playbook.
Chapter 2, Going Modular with Ansible Roles, will demonstrate creating modular reusable automation code using Ansible roles, which are units of automation.
Chapter 3, Separating Code and Data – Variables, Facts, and Templates, covers the creation of flexible, customizable, data-driven roles with templates and variables. You will also learn about auto-discovered variables, that is, facts.
Chapter 4, Bringing In Your Code – Custom Commands and Scripts, covers bringing in your existing scripts and invoking Shell commands with Ansible.
Chapter 5, Controlling Execution Flow – Conditionals, discusses the control structures offered by Ansible to change the direction of execution.
Chapter 6, Iterative Control Structures – Loops, demonstrates how to iterate over arrays, hashes, and so on, using omnipotent with statements.
Chapter 7, Node Discovery and Clustering, discusses the discovery of topology information and creates dynamic configurations using magic variables and facts caching.
Chapter 8, Encrypting Data with Vault, discusses secure variables stored in, and shared with, version control systems using Ansible-vault.
Chapter 9, Managing Environments, covers the creation and management of isolated environments with Ansible and mapping automation code to the software development workflow.
Chapter 10, Orchestrating Infrastructure with Ansible, covers the orchestration features of Ansible, such as rolling updates, pre-tasks and post-tasks, tags, building tests into the playbook, and so on.
This book assumes that you have a working installation of Ansible and a good knowledge of Linux/Unix environments and systems operations, and that you are familiar working with the command-line interface.
The target audience for this book are systems or automation engineers with a few years of experience in managing various parts of infrastructure, including operating systems, application configurations, and deployments. This book also targets anyone who intends to manage systems and application configurations effectively and in an automated way, with the shortest learning curve.
It is assumed that readers have a conceptual understanding of Ansible, have already installed it and are familiar with basic operations such as creating inventory file and running ad hoc commands with Ansible.
In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text are shown as follows: "We can include other contexts through the use of the include directive."
A block of code is set as follows:
--- # site.yml : This is a sitewide playbook - include: www.yml
Any command-line input or output is written as follows:
$ ansible-playbook simple_playbook.yml -i customhosts
New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "The resultant variable hash should contain items from defaults plus the overridden values from vars".
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