Introduction in Ansible
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About Ansible
=============
* **K-I-S-S** configuration management tool
* invented by **Michael DeHaan**
* project started in **2012**
* written in **Python**
* open source
* **configuration as data**, not code -> no coding skills needed
* human readable configuration
* big community


Functions
=========
* configuration management tool
* application deployment
* orchestration tool
* remote execution


Architecture
============
* agentless architecture
* masterless -> can run from everywhere
* python is needed on the managed host
* yaml definition
* jinja2 template engine
* a lot of modules for different tasks (packages, services, configs, ...)
* idempotent -> always get the same state on the managed host
* communication methods

    * push via ssh (recommended)
    * pull from SCM and run locally
    * manage everything local

Requirements
============

Control Machine Requirements
----------------------------
* Ansible Core
* Python 2.4 or later
* Inventory & Config File
* Ansible project


Managed Node Requirements
-------------------------
* SSH for push architecture
* Python 2.4 or later


Terminology
===========

* Playbooks contain Plays

    * Plays contain Roles (or Tasks)

        * Roles contain Tasks

            * Tasks call Modules


.. image:: /../_static/terminology.png
   :class: align-center


First steps
===========

on the Control Machine
----------------------
* Installation of Ansible
* Create a user
* Create a ssh-key
* Rollout the ssh-key to all managed Nodes
* Test SSH connection (without Ansible)
* add managed nodes to inventory file
* add basic configuration file ``ansible.cfg``
* run your first Ansible tests

on the managed Nodes
--------------------
* Create a user
* add sudo rule


Links
-----
* http://www.ansible.com/get-started
* http://www.ansible.com/how-ansible-works
* http://www.ansible.com/community
* http://docs.ansible.com/ansible/playbooks_intro.html#ansible-pull

Installation of Ansible
=======================
* from OS packages
* from pip
* from git

.. code-block:: bash

    # via apt on debian/ubuntu
    apt-get install ansible

    # via yum on redhat/centos - EPEL repo needed
    yum install ansible

    # via pip
    pip install ansible

    # via github
    git clone https://github.com/ansible/ansible.git


.. hint::

    On Red Hat / Centos is the **EPEL** Channel needed.

.. important::

    On some distributions is not the latest Ansible version available if you install Ansible via OS package manager. In that case, use ``pip``.

.. hint::

    Ansible installation via ``pip`` includes no configuration file.


Links
-----
* http://docs.ansible.com/ansible/intro_installation.html



Installation of PIP
===================

On **Debian**-based Linux derivates

.. code:: bash

    apt-get install python-pip

On **RedHat**-based Linux derivates (EPEL repo needed)

.. code:: bash

    yum install python-pip

On **Mac OS X** ``pip`` will automatically be installed if you install Python by ``brew``

.. code:: bash

    brew install python

.. hint::

    In case ``brew`` cannot be found you've to install `Homebrew <http://brew.sh/>`_ first.