.. _inventory_plugins:

Inventory plugins
=================

.. contents::
   :local:
   :depth: 2

Inventory plugins allow users to point at data sources to compile the inventory of hosts that Ansible uses to target tasks, either using the ``-i /path/to/file`` and/or ``-i 'host1, host2'`` command line parameters or from other configuration sources. If necessary, you can :ref:`create custom inventory plugins <developing_inventory_plugins>`.

.. _enabling_inventory:

Enabling inventory plugins
--------------------------

Most inventory plugins shipped with Ansible are enabled by default or can be used by with the ``auto`` plugin.

In some circumstances, for example, if the inventory plugin does not use a YAML configuration file, you may need to enable the specific plugin. You can do this by setting ``enable_plugins`` in your :ref:`ansible.cfg <ansible_configuration_settings>` file in the ``[inventory]`` section. Modifying this will override the default list of enabled plugins. Here is the default list of enabled plugins that ships with Ansible:

.. code-block:: ini

   [inventory]
   enable_plugins = host_list, script, auto, yaml, ini, toml

If the plugin is in a collection and is not being picked up by the `auto` statement, you can append the fully qualified name:

.. code-block:: ini

   [inventory]
   enable_plugins = host_list, script, auto, yaml, ini, toml, namespace.collection_name.inventory_plugin_name

Or, if it is a local plugin, perhaps stored in the path set by :ref:`DEFAULT_INVENTORY_PLUGIN_PATH`, you could reference it as follows:

.. code-block:: ini

   [inventory]
   enable_plugins = host_list, script, auto, yaml, ini, toml, my_plugin
   
If you use a plugin that supports a YAML configuration source, make sure that the name matches the name provided in the ``plugin`` entry of the inventory source file.

.. _using_inventory:

Using inventory plugins
-----------------------

To use an inventory plugin, you must provide an inventory source. Most of the time this is a file containing host information or a YAML configuration file with options for the plugin. You can use the ``-i`` flag to provide inventory sources or configure a default inventory path.

.. code-block:: bash

   ansible hostname -i inventory_source -m ansible.builtin.ping

To start using an inventory plugin with a YAML configuration source, create a file with the accepted filename schema documented for the plugin in question, then add ``plugin: plugin_name``. Use the fully qualified name if the plugin is in a collection.

.. code-block:: yaml

   # demo.aws_ec2.yml
   plugin: amazon.aws.aws_ec2

Each plugin should document any naming restrictions. In addition, the YAML config file must end with the extension ``yml`` or ``yaml`` to be enabled by default with the ``auto`` plugin (otherwise, see the section above on enabling plugins).

After providing any required options, you can view the populated inventory with ``ansible-inventory -i demo.aws_ec2.yml --graph``:

.. code-block:: text

    @all:
      |--@aws_ec2:
      |  |--ec2-12-345-678-901.compute-1.amazonaws.com
      |  |--ec2-98-765-432-10.compute-1.amazonaws.com
      |--@ungrouped:

If you are using an inventory plugin in a playbook-adjacent collection and want to test your setup with ``ansible-inventory``, use the ``--playbook-dir`` flag.

Your inventory source might be a directory of inventory configuration files. The constructed inventory plugin only operates on those hosts already in inventory, so you may want the constructed inventory configuration parsed at a particular point (such as last). Ansible parses the directory recursively, alphabetically. You cannot configure the parsing approach, so name your files to make it work predictably. Inventory plugins that extend constructed features directly can work around that restriction by adding constructed options in addition to the inventory plugin options. Otherwise, you can use ``-i`` with multiple sources to impose a specific order, for example ``-i demo.aws_ec2.yml -i clouds.yml -i constructed.yml``.

You can create dynamic groups using host variables with the constructed ``keyed_groups`` option. The option ``groups`` can also be used to create groups and ``compose`` creates and modifies host variables. Here is an aws_ec2 example utilizing constructed features:

.. code-block:: yaml

    # demo.aws_ec2.yml
    plugin: amazon.aws.aws_ec2
    regions:
      - us-east-1
      - us-east-2
    keyed_groups:
      # add hosts to tag_Name_value groups for each aws_ec2 host's tags.Name variable
      - key: tags.Name
        prefix: tag_Name_
        separator: ""
      # If you have a tag called "Role" which has the value "Webserver", this will add the group
      # role_Webserver and add any hosts that have that tag assigned to it.
      - key: tags.Role
        prefix: role
    groups:
      # add hosts to the group development if any of the dictionary's keys or values is the word 'devel'
      development: "'devel' in (tags|list)"
      # add hosts to the "private_only" group if the host doesn't have a public IP associated to it
      private_only: "public_ip_address is not defined"
    compose:
      # use a private address where a public one isn't assigned
      ansible_host: public_ip_address|default(private_ip_address)
      # alternatively, set the ansible_host variable to connect with the private IP address without changing the hostname
      # ansible_host: private_ip_address
      # if you *must* set a string here (perhaps to identify the inventory source if you have multiple
      # accounts you want to use as sources), you need to wrap this in two sets of quotes, either ' then "
      # or " then '
      some_inventory_wide_string: '"Yes, you need both types of quotes here"'

Now the output of ``ansible-inventory -i demo.aws_ec2.yml --graph``:

.. code-block:: text

    @all:
      |--@aws_ec2:
      |  |--ec2-12-345-678-901.compute-1.amazonaws.com
      |  |--ec2-98-765-432-10.compute-1.amazonaws.com
      |  |--...
      |--@development:
      |  |--ec2-12-345-678-901.compute-1.amazonaws.com
      |  |--ec2-98-765-432-10.compute-1.amazonaws.com
      |--@role_Webserver
      |  |--ec2-12-345-678-901.compute-1.amazonaws.com
      |--@tag_Name_ECS_Instance:
      |  |--ec2-98-765-432-10.compute-1.amazonaws.com
      |--@tag_Name_Test_Server:
      |  |--ec2-12-345-678-901.compute-1.amazonaws.com
      |--@ungrouped

If a host does not have the variables in the configuration above (in other words, ``tags.Name``, ``tags``, ``private_ip_address``), the host will not be added to groups other than those that the inventory plugin creates and the ``ansible_host`` host variable will not be modified.

Inventory plugins that support caching can use the general settings for the fact cache defined in the ``ansible.cfg`` file's ``[defaults]`` section or define inventory-specific settings in the ``[inventory]`` section. Individual plugins can define plugin-specific cache settings in their config file:

.. code-block:: yaml

    # demo.aws_ec2.yml
    plugin: amazon.aws.aws_ec2
    cache: true
    cache_plugin: ansible.builtin.jsonfile
    cache_timeout: 7200
    cache_connection: /tmp/aws_inventory
    cache_prefix: aws_ec2

Here is an example of setting inventory caching with some fact caching defaults for the cache plugin used and the timeout in an ``ansible.cfg`` file:

.. code-block:: ini

   [defaults]
   fact_caching = ansible.builtin.jsonfile
   fact_caching_connection = /tmp/ansible_facts
   cache_timeout = 3600

   [inventory]
   cache = yes
   cache_connection = /tmp/ansible_inventory

.. _inventory_plugin_list:

Plugin list
-----------

You can use ``ansible-doc -t inventory -l`` to see the list of available plugins.
Use ``ansible-doc -t inventory <plugin name>`` to see plugin-specific documentation and examples.

.. seealso::

   :ref:`about_playbooks`
       An introduction to playbooks
   :ref:`callback_plugins`
       Callback plugins
   :ref:`connection_plugins`
       Connection plugins
   :ref:`filter_plugins`
       Filter plugins
   :ref:`test_plugins`
       Test plugins
   :ref:`lookup_plugins`
       Lookup plugins
   :ref:`vars_plugins`
       Vars plugins
   `User Mailing List <https://groups.google.com/group/ansible-devel>`_
       Have a question?  Stop by the google group!
   :ref:`communication_irc`
       How to join Ansible chat channels
