Book Image

Ansible Playbook Essentials

By : Gourav Shah, GOURAV JAWAHAR SHAH
Book Image

Ansible Playbook Essentials

By: Gourav Shah, GOURAV JAWAHAR SHAH

Overview of this book

Ansible Playbook Essentials will show you how to write a blueprint of your infrastructure, encompassing multitier applications using Ansible's playbooks. Beginning with basic concepts such as plays, tasks, handlers, inventory, and YAML Ain't Markup Language (YAML) syntax that Ansible uses, you'll understand how to organize your code into a modular structure. Building on this, you will study techniques to create data-driven playbooks with variables, templates, logical constructs, and encrypted data, which will further strengthen your application skills in Ansible. Adding to this, the book will also take you through advanced clustering concepts, such as discovering topology information about other nodes in the cluster and managing multiple environments with isolated configurations. As you approach the concluding chapters, you can expect to learn about orchestrating infrastructure and deploying applications in a coordinated manner. By the end of this book, you will be able to design solutions to your automation and orchestration problems using playbooks quickly and efficiently.

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Ansible Playbook Essentials
Gourav Shah | GOURAV JAWAHAR SHAH
Aug, 2015 | 168 pages
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Table of Contents (20 chapters)
Ansible Playbook Essentials
Ansible Playbook Essentials
Credits
Credits
About the Author
About the Author
Acknowledgments
Acknowledgments
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Setting Up the Learning Environment
Setting Up the Learning Environment
Free Chapter
1
Blueprinting Your Infrastructure
Blueprinting Your Infrastructure
Getting introduced to Ansible
Plays
Our first playbook
Review questions
Summary
2
Going Modular with Ansible Roles
Going Modular with Ansible Roles
Understanding roles
Naming roles
The directory layout for roles
Creating a site-wide playbook, nesting, and using include statements
Creating the www playbook
Creating a base role
Creating an Nginx role
Automating events and actions with handlers
Adding pre-tasks and post-tasks to playbooks
Running playbooks with roles
Review questions
Summary
3
Separating Code and Data – Variables, Facts, and Templates
Separating Code and Data – Variables, Facts, and Templates
Static content explosion
Separating code and data
Jinja2 templates
Facts and variables
Templating the Nginx configurations
Adding another layer – the MySQL role
Variable precedence
The best practices for variable usage
Review questions
Summary
4
Bringing In Your Code – Custom Commands and Scripts
Bringing In Your Code – Custom Commands and Scripts
The command modules
Deploying a WordPress application – a hands-on approach
Review questions
Summary
5
Controlling Execution Flow – Conditionals
Controlling Execution Flow – Conditionals
The conditional control structure
Refactoring the MySQL role
Conditional control structure in Jinja2 templates
Running a task only once
Executing roles conditionally
Review questions
Summary
6
Iterative Control Structures – Loops
Iterative Control Structures – Loops
The omnipotent with statement
Configuring WordPress requisites
The PHP5-FPM role
Creating MySQL databases and user accounts
Creating Nginx virtual hosts
Review questions
Summary
7
Node Discovery and Clustering
Node Discovery and Clustering
Node discovery with magic variables
Creating the load balancer role
Accessing facts for non-playbook hosts
Review questions
Summary
8
Encrypting Data with Vault
Encrypting Data with Vault
Ansible-vault
Using the Ansible-vault
Encrypting the database credentials
Using a password file
Adding the vault password file option to the Ansible configuration
Review questions
Summary
9
Managing Environments
Managing Environments
Approaches for managing environments
Creating a development environment
Review questions
Summary
10
Orchestrating Infrastructure with Ansible
Orchestrating Infrastructure with Ansible
Ansible as an orchestrator
Tagging the roles
Creating an orchestration playbook for WordPress
Review questions
Summary
References
References
Index
Index

Creating a base role

In the previous chapter, we created a simple playbook with all plays written inside the same file. After discovering new and exciting information about roles, we will start refactoring our code and making it modular.

Refactoring our code – creating a base role

We have written two plays in the simple_playbook.yml file. We intended to run the first play on all hosts. This play has tasks to create users, install essential packages, and so on:

It's a good practice to combine all such essential tasks and create a base role. You can name it as base, common, essential, or whatever you please, but the concept remains the same. We will now move this code to the base role:

  1. Create the directory layout for the base role. Since we are only going to specify tasks, we just need one subdirectory inside the base:

    $ mkdir -p roles/base/tasks

  2. Create the main.yml file inside roles/base/tasks to specify tasks for the base role.

  3. Edit the main.yml file and add the following code:

    ---
# essential...
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