99 lines
3.7 KiB
ReStructuredText
99 lines
3.7 KiB
ReStructuredText
Developing Dynamic Inventory Sources
|
|
====================================
|
|
|
|
.. contents:: Topics
|
|
:local:
|
|
|
|
As described in :doc:`intro_dynamic_inventory`, ansible can pull inventory information from dynamic sources, including cloud sources.
|
|
|
|
How do we write a new one?
|
|
|
|
Simple! We just create a script or program that can return JSON in the right format when fed the proper arguments.
|
|
You can do this in any language.
|
|
|
|
.. _inventory_script_conventions:
|
|
|
|
Script Conventions
|
|
``````````````````
|
|
|
|
When the external node script is called with the single argument ``--list``, the script must return a JSON hash/dictionary of all the groups to be managed. Each group's value should be either a hash/dictionary containing a list of each host/IP, potential child groups, and potential group variables, or simply a list of host/IP addresses, like so::
|
|
|
|
{
|
|
"databases" : {
|
|
"hosts" : [ "host1.example.com", "host2.example.com" ],
|
|
"vars" : {
|
|
"a" : true
|
|
}
|
|
},
|
|
"webservers" : [ "host2.example.com", "host3.example.com" ],
|
|
"atlanta" : {
|
|
"hosts" : [ "host1.example.com", "host4.example.com", "host5.example.com" ],
|
|
"vars" : {
|
|
"b" : false
|
|
},
|
|
"children": [ "marietta", "5points" ]
|
|
},
|
|
"marietta" : [ "host6.example.com" ],
|
|
"5points" : [ "host7.example.com" ]
|
|
}
|
|
|
|
.. versionadded:: 1.0
|
|
|
|
Before version 1.0, each group could only have a list of hostnames/IP addresses, like the webservers, marietta, and 5points groups above.
|
|
|
|
When called with the arguments ``--host <hostname>`` (where <hostname> is a host from above), the script must return either an empty JSON
|
|
hash/dictionary, or a hash/dictionary of variables to make available to templates and playbooks. Returning variables is optional,
|
|
if the script does not wish to do this, returning an empty hash/dictionary is the way to go::
|
|
|
|
{
|
|
"favcolor" : "red",
|
|
"ntpserver" : "wolf.example.com",
|
|
"monitoring" : "pack.example.com"
|
|
}
|
|
|
|
.. _inventory_script_tuning:
|
|
|
|
Tuning the External Inventory Script
|
|
````````````````````````````````````
|
|
|
|
.. versionadded:: 1.3
|
|
|
|
The stock inventory script system detailed above works for all versions of Ansible, but calling
|
|
``--host`` for every host can be rather expensive, especially if it involves expensive API calls to
|
|
a remote subsystem. In Ansible
|
|
1.3 or later, if the inventory script returns a top level element called "_meta", it is possible
|
|
to return all of the host variables in one inventory script call. When this meta element contains
|
|
a value for "hostvars", the inventory script will not be invoked with ``--host`` for each host. This
|
|
results in a significant performance increase for large numbers of hosts, and also makes client
|
|
side caching easier to implement for the inventory script.
|
|
|
|
The data to be added to the top level JSON dictionary looks like this::
|
|
|
|
{
|
|
|
|
# results of inventory script as above go here
|
|
# ...
|
|
|
|
"_meta" : {
|
|
"hostvars" : {
|
|
"moocow.example.com" : { "asdf" : 1234 },
|
|
"llama.example.com" : { "asdf" : 5678 },
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
.. seealso::
|
|
|
|
:doc:`developing_api`
|
|
Python API to Playbooks and Ad Hoc Task Execution
|
|
:doc:`developing_modules`
|
|
How to develop modules
|
|
:doc:`developing_plugins`
|
|
How to develop plugins
|
|
`Ansible Tower <http://ansible.com/ansible-tower>`_
|
|
REST API endpoint and GUI for Ansible, syncs with dynamic inventory
|
|
`Development Mailing List <http://groups.google.com/group/ansible-devel>`_
|
|
Mailing list for development topics
|
|
`irc.freenode.net <http://irc.freenode.net>`_
|
|
#ansible IRC chat channel
|