Ansible tutorial

This tutorial presents Ansible step-by-step. You’ll need to have a (virtual or physical) machine to act as an Ansible node.

Ansible is a configuration management software that lets you control and configure nodes from another machine. What makes it different from other management software is that Ansible uses (potentially existing) SSH infrastructure, while others (Chef, Puppet, …) need a specific PKI infrastructure to be set up.

Ansible also emphasises push mode, where configuration is pushed from a master machine (a master machine is only a machine where you can SSH to nodes from) to nodes, while most other CM typically do it the other way around (nodes pull their config at times from a master machine).

This mode is really interesting since you do not need to have a ‘publicly’ accessible ‘master’ to be able to configure remote nodes: it’s the nodes that need to be accessible (we’ll see later that ‘hidden’ nodes can pull their configuration too!), and most of the time they are.

Prerequisites for Ansible

You need the following python modules on your machine (the machine you run ansible on)

python-yaml
python-jinja2

On Debian/Ubuntu run: sudo apt-get install python-yaml python-jinja2 python-paramiko python-crypto

We’re also assuming you have a keypair in your ~/.ssh directory.

Installing Ansible

From source

Ansible devel branch is always usable, so we’ll run straight from a git checkout. You might need to install git for this (sudo apt-get install git on Debian/Ubuntu).

git clone git://github.com/ansible/ansible.git
cd ./ansible

At this point, we can load the Ansible environment:

source ./hacking/env-setup

Cloning the tutorial

git clone https://github.com/remyleone/cloud-courses
cd cloud-courses/ansible

Terminology:

command or action: ansible module executed in stand-alone mode. Intro in example02.
task: combines an action (a module and its arguments) with a name and optionally some other keywords (like looping directives).
play: a yaml structure executing a list of roles or tasks over a list of hosts
playbook: yaml file containing multiple plays. Intro in example04.
role: an organisational unit grouping tasks together in order to achieve something (install a piece of software for instance). Intro in example12.

Just in case you want to skip to a specific step, here is a topic table of contents.

Check to see if Ansible is installed?