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143 lines
4.0 KiB
ReStructuredText
.. _patterns:
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The Inventory File, Patterns, and Groups
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========================================
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Ansible works against multiple systems in your infrastructure at the
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same time. It does this by selecting portions of systems listed in
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Ansible's inventory file, which defaults to /etc/ansible/hosts.
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.. _inventoryformat:
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Basic Inventory File Format
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+++++++++++++++++++++++++++
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The format for /etc/ansible/hosts looks like this::
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mail.example.com
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[webservers]
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foo.example.com
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bar.example.com
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[dbservers]
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one.example.com
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two.example.com
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three.example.com
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The things in brackets are group names, you don't have to have them,
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but they are useful.
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If you have hosts that run on non-standard SSH ports you can put the port number
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after the hostname with a colon. This requires Ansible 0.3 (integration branch)::
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four.example.com:5309
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Selecting Targets
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+++++++++++++++++
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We'll go over how to use the command line in :doc:`examples` section, however, basically it looks like this::
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ansible <pattern_goes_here> -m <module_name> -a <arguments>
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Such as::
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ansible webservers -m service -a "name=httpd state=restarted"
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Within :doc:`playbooks`, these patterns can also be used, for even greater purposes.
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Anyway, to use Ansible, you'll first need to know how to tell Ansible which hosts in your inventory file to talk to.
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This is done by designating particular host names or groups of hosts.
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The following patterns target all hosts in the inventory file::
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all
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*
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Basically 'all' is an alias for '*'. It is also possible to address a specific host or hosts::
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one.example.com
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one.example.com:two.example.com
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192.168.1.50
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192.168.1.*
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The following patterns address one or more groups, which are denoted
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with the aforementioned bracket headers in the inventory file::
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webservers
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webservers:dbservers
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Individual host names (or IPs), but not groups, can also be referenced using
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wildcards::
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*.example.com
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*.com
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It's also ok to mix wildcard patterns and groups at the same time::
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one*.com:dbservers
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.. note::
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It is not possible to target a host not in the inventory file. This is a safety feature.
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Easy enough. See :doc:`examples` and then :doc:`playbooks` for how to do things to selected hosts.
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Advanced Inventory File Format
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++++++++++++++++++++++++++++++
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(This features requires the integration branch of Ansible, soon to be release 0.3)
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Once you read about playbooks you'll quickly see how useful it will be to assign particular variables
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to particular hosts and groups of hosts. While the default INI-style host format doesn't allow this,
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switching to the YAML inventory format can add some compelling capabilities. Just replace your INI
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style file with a YAML one.::
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---
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# some ungrouped hosts, either use the short string form or the "host: " prefix
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- host: jupiter
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- mars
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# variables can be assigned like this...
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- host: saturn
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vars:
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- moon: titan
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# groups can also set variables to all hosts in the group
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# here are a bunch of hosts using a non-standard SSH port
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# and also defining a variable 'ntpserver'
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- group: greek
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hosts:
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- zeus
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- hera
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- poseidon
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vars:
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- ansible_ssh_port: 3000
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- ntp_server: olympus.example.com
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# individual hosts can still set variables inside of groups too
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# so you aren't limited to just group variables and host variables.
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- group: norse
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hosts:
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- host: thor
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vars:
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- hammer: True
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- odin
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- loki
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vars:
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- asdf: 1234
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Tip: Be sure to start your YAML file with the YAML record designator "---".
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.. seealso::
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:doc:`examples`
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Examples of basic commands
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:doc:`playbooks`
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Learning ansible's configuration management language
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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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