Since CFEngine was first created by Mark Burgess in 1993, configuration management tools have been constantly evolving. Followed by the emergence of more modern tools such as Puppet and Chef, there are now a large number of choices available to a system administrator.
Ansible is one of the newer tools to arrive into the configuration management space. Where other tools have focused on completeness and configurability, Ansible has bucked the trend and, instead, focused on simplicity and ease of use.
In this book, we aim to show you how to use Ansible from the humble beginnings of its CLI tool, to writing playbooks, and then managing large and complex environments. Finally, we teach you how to build your own modules and extend Ansible by writing plugins that add new features.
Chapter 1, Getting Started with Ansible, teaches you the basics of Ansible, how to install it on Windows and Linux, how to build an inventory, how to use modules, and, most importantly, how to get help.
Chapter 2, Simple Playbooks, teaches you how to combine multiple modules to create Ansible playbooks to manage your hosts, it also covers a few useful modules.
Chapter 3, Advanced Playbooks, delves deeper into Ansible's scripting language and teaches you more complex language constructs; here we also explain how to debug playbooks.
Chapter 4, Larger Projects, teaches you the techniques to scale Ansible's configurations to large deployments using many complicated systems, including how to manage various secrets you may use to provision your systems.
Chapter 5, Custom Modules, teaches you how to expand Ansible beyond its current capabilities by writing both modules and plugins.
To use this book, you will need at least the following:
A text editor
A machine with the Linux operating system
Python 2.6.x or Python 2.7.x
However, to use Ansible to its full effect, you should have several Linux machines available to be managed. You can use a virtualization platform to simulate many hosts, if required. To use the Windows modules, you will need both a Windows machine to be managed and a Linux machine to be the controller.
This book is intended for people who want to understand the basics of how Ansible works. It is expected that you have rudimentary knowledge of how to set up and configure Linux machines. In parts of the book, we cover the configuration files of BIND, MySQL, and other Linux daemons; a working knowledge of these would be helpful, but is certainly not required.
In this book, you will find a number of styles of text that distinguish among different kinds of information. Here are some examples of these styles, and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "This is done in a similar way using the vars_files directive."
A block of code is set as follows:
[group] machine1 machine2 machine3
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
tasks:
- name: install apache
action: yum name=httpd state=installed
- name: configure apache
copy: src=files/httpd.conf dest=/etc/httpd/conf/httpd.confAny command-line input or output is written as follows:
ansible machinename -u root -k -m ping
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: "clicking the Next button moves you to the next screen".
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