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. A vagrant environment is provided for going through this tutorial.

Ansible is a configuration management software that let's 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

From a deb package

When running from an installed package, this is absolutely not necessary. If you prefer running from a debian package ansible, provides a make target to build it. You need a few packages to build the deb:

sudo apt-get install make fakeroot cdbs python-support
git clone git://github.com/ansible/ansible.git
cd ./ansible
make deb
sudo dpkg -i ../ansible_1.1_all.deb (version may vary)

We'll assume you're using the deb packages in the rest of this tutorial.

Cloning the tutorial

git clone https://github.com/leucos/ansible-tuto.git
cd ansible-tuto

Using Vagrant with the tutorial

It's highly recommended to use Vagrant to follow this tutorial. If you don't have it already, setting up should be quite easy and is described in step-00/README.md.

If you wish to proceed without Vagrant (not recommended!), go straight to step-01/README.md.

Terminology:

command or action: ansible module like just a shell command. Intro in step-02.
task: it's combine an action (a module and its arguments) with a name and optionally some other keywords (like looping directives).
playbook: an yaml file contains roles executed in sequence, and eventually individual tasks. Intro in step-04.
role: an organisational unit grouping tasks together in order to install a piece of software. Intro in step-12.

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

Contributing

Thanks to all people who have contributed to this tutorial:

I've been using Ansible almost since it's birth, but I learned a lot in the process of writing it. If you want to jump in, it's a great way to learn, feel free to add your contributions.

The chapters being written live in the writing branch.

If you have ideas on topics that would require a chapter, please open a PR.

I'm also open on pairing for writing chapters. Drop me a note if you're interested.

If you make changes or add chapters, please fill the test/expectations file and run the tests (test/run.sh). See the test/run.sh file for (a bit) more information.

When adding a new chapter (e.g. step-NN), please issue:

cd step-99
ln -sf ../step-NN/{hosts,roles,site.yml,group_vars,host_vars} .

For typos, grammar, etc... please send a PR for the master branch directly.

Thank you!

Dr4ik/ansible-tuto