Modules
"""""""

About Modules
=============
* changes with Ansible are done by modules
* Ansible provides a lot of common modules (called the **module library**)
* common modules are written in Python
* you can write your own modules in any language
* Core Modules shipped with Ansible Core
* Extra Modules via github, new also as own package
* modules can be used to only check a state without executing
* some modules can also be used to compare the state and show the differences
* every module has a documentation with examples

    * `Online Docs <http://docs.ansible.com/ansible/list_of_all_modules.html>`_
    * ``ansible-doc`` Binary

.. hint::
    
    If you're familiar with role/profiles design pattern in Puppet, keep in mind there is no such thing in Ansible. Ansible modules are roles. 

.. important::

    Use modules, they are tested, often used and idempotent.


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


Popular Modules
===============
There are modules for almost everything:

* Package Management (like ``yum``, ``apt``)
* Remote Execution (``command``, ``shell``)
* Service Management (like ``service``)
* File Handling (``copy``, ``template``)
* SCM (like ``git``, ``subversion``)
* User / Group Handling (like ``user``, ``group``)
* Web / Database Management
* Cloud Services
* Network Services

And there are many more, checkout the links below with all the categories.

Links
-----
* http://docs.ansible.com/ansible/modules_by_category.html
* http://docs.ansible.com/ansible/list_of_all_modules.html
* http://docs.ansible.com/ansible/modules.html
* https://github.com/ansible/ansible-modules-core
* https://github.com/ansible/ansible-modules-extras


Run a modul as ad-hoc command
=============================

.. code-block:: bash

    ansible -m <modul> -a <argument> <host(s)/hostgroup>

    # install tree package on db hosts
    ansible -m package -a "name=tree state=present" db