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Conditional imports are described under conditionals so remove the duplicate section.

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Michael DeHaan 2014-08-08 13:19:35 -04:00
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docsite/rst/playbooks_variables.rst
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@ -869,64 +869,6 @@ As of Ansible 1.3, extra vars can be loaded from a JSON file with the "@" syntax
Also as of Ansible 1.3, extra vars can be formatted as YAML, either on the command line Also as of Ansible 1.3, extra vars can be formatted as YAML, either on the command line
or in a file as above. or in a file as above.
.. _conditional_imports:
Conditional Imports
```````````````````
.. note:: This behavior is infrequently used in Ansible. You may wish to skip this section. The 'group_by' module as described in the module documentation is a better way to achieve this behavior in most cases.
Sometimes you will want to do certain things differently in a playbook based on certain criteria.
Having one playbook that works on multiple platforms and OS versions is a good example.
As an example, the name of the Apache package may be different between CentOS and Debian,
but it is easily handled with a minimum of syntax in an Ansible Playbook::
---
- hosts: all
remote_user: root
vars_files:
- "vars/common.yml"
- [ "vars/{{ ansible_os_family }}.yml", "vars/os_defaults.yml" ]
tasks:
- name: make sure apache is running
service: name={{ apache }} state=running
.. note::
The variable 'ansible_os_family' is being interpolated into
the list of filenames being defined for vars_files.
As a reminder, the various YAML files contain just keys and values::
---
# for vars/CentOS.yml
apache: httpd
somethingelse: 42
How does this work? If the operating system was 'CentOS', the first file Ansible would try to import
would be 'vars/CentOS.yml', followed by '/vars/os_defaults.yml' if that file
did not exist. If no files in the list were found, an error would be raised.
On Debian, it would instead first look towards 'vars/Debian.yml' instead of 'vars/CentOS.yml', before
falling back on 'vars/os_defaults.yml'. Pretty simple.
To use this conditional import feature, you'll need facter or ohai installed prior to running the playbook, but
you can of course push this out with Ansible if you like::
# for facter
ansible -m yum -a "pkg=facter ensure=installed"
ansible -m yum -a "pkg=ruby-json ensure=installed"
# for ohai
ansible -m yum -a "pkg=ohai ensure=installed"
Ansible's approach to configuration -- separating variables from tasks, keeps your playbooks
from turning into arbitrary code with ugly nested ifs, conditionals, and so on - and results
in more streamlined & auditable configuration rules -- especially because there are a
minimum of decision points to track.
.. _variable_precedence: .. _variable_precedence:
Variable Precedence: Where Should I Put A Variable? Variable Precedence: Where Should I Put A Variable?