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About Modules
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=============
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.. toctree::
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:maxdepth: 4
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.. _modules_intro:
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Introduction
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````````````
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Ansible ships with a number of modules (called the 'module library')
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that can be executed directly on remote hosts or through :doc:`Playbooks <playbooks>`.
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Users can also write their own modules. These modules can control system resources, like services, packages, or files (anything really), or
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handle executing system commands.
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Let's review how we execute three different modules from the command line::
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ansible webservers -m service -a "name=httpd state=started"
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ansible webservers -m ping
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ansible webservers -m command -a "/sbin/reboot -t now"
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Each module supports taking arguments. Nearly all modules take ``key=value``
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arguments, space delimited. Some modules take no arguments, and the command/shell modules simply
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take the string of the command you want to run.
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From playbooks, Ansible modules are executed in a very similar way::
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- name: reboot the servers
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action: command /sbin/reboot -t now
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Which can be abbreviated to::
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- name: reboot the servers
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command: /sbin/reboot -t now
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All modules technically return JSON format data, though if you are using the command line or playbooks, you don't really need to know much about
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that. If you're writing your own module, you care, and this means you do not have to write modules in any particular language -- you get to choose.
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Modules are `idempotent`, meaning they will seek to avoid changes to the system unless a change needs to be made. When using Ansible
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playbooks, these modules can trigger 'change events' in the form of notifying 'handlers' to run additional tasks.
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Documentation for each module can be accessed from the command line with the ansible-doc tool::
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ansible-doc yum
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.. seealso::
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:doc:`intro_adhoc`
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Examples of using modules in /usr/bin/ansible
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:doc:`playbooks`
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Examples of using modules with /usr/bin/ansible-playbook
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:doc:`developing_modules`
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How to write your own modules
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:doc:`developing_api`
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Examples of using modules with the Python API
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`Mailing List <http://groups.google.com/group/ansible-project>`_
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Questions? Help? Ideas? Stop by the list on Google Groups
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`irc.freenode.net <http://irc.freenode.net>`_
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#ansible IRC chat channel
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