.. _get_started_inventory:

Building an inventory

Inventories organize managed nodes in centralized files that provide Ansible with system information and network locations. Using an inventory file, Ansible can manage a large number of hosts with a single command.

To complete the following steps, you will need the IP address or fully qualified domain name (FQDN) of at least one host system. For demonstration purposes, the host could be running locally in a container or a virtual machine. You must also ensure that your public SSH key is added to the authorized_keys file on each host.

Continue getting started with Ansible and build an inventory as follows:

#. Create a file named inventory.ini in the ansible_quickstart directory that you created in the :ref:preceding step<get_started_ansible>. #. Add a new [myhosts] group to the inventory.ini file and specify the IP address or fully qualified domain name (FQDN) of each host system.

.. code-block:: ini

  [myhosts]
  192.0.2.50
  192.0.2.51
  192.0.2.52

#. Verify your inventory.

.. code-block:: bash

  ansible-inventory -i inventory.ini --list

#. Ping the myhosts group in your inventory.

.. code-block:: bash

  ansible myhosts -m ping -i inventory.ini

.. note:: Pass the -u option with the ansible command if the username is different on the control node and the managed node(s).

.. literalinclude:: ansible_output/ping_inventory_output.txt :language: text

Congratulations, you have successfully built an inventory. Continue getting started with Ansible by :ref:creating a playbook<get_started_playbook>.

Inventories in INI or YAML format

You can create inventories in either INI files or in YAML. In most cases, such as the example in the preceding steps, INI files are straightforward and easy to read for a small number of managed nodes.

Creating an inventory in YAML format becomes a sensible option as the number of managed nodes increases. For example, the following is an equivalent of the inventory.ini that declares unique names for managed nodes and uses the ansible_host field:

.. literalinclude:: yaml/inventory_example_vms.yaml :language: yaml

Tips for building inventories

Ensure that group names are meaningful and unique. Group names are also case sensitive.
Avoid spaces, hyphens, and preceding numbers (use floor_19, not 19th_floor) in group names.
Group hosts in your inventory logically according to their What, Where, and When.

What Group hosts according to the topology, for example: db, web, leaf, spine. Where Group hosts by geographic location, for example: datacenter, region, floor, building. When Group hosts by stage, for example: development, test, staging, production.

Use metagroups

Create a metagroup that organizes multiple groups in your inventory with the following syntax:

.. code-block:: yaml

metagroupname: children:

The following inventory illustrates a basic structure for a data center. This example inventory contains a network metagroup that includes all network devices and a datacenter metagroup that includes the network group and all webservers.

.. literalinclude:: yaml/inventory_group_structure.yaml :language: yaml

Create variables

Variables set values for managed nodes, such as the IP address, FQDN, operating system, and SSH user, so you do not need to pass them when running Ansible commands.

Variables can apply to specific hosts.

.. literalinclude:: yaml/inventory_variables_host.yaml :language: yaml

Variables can also apply to all hosts in a group.

.. literalinclude:: yaml/inventory_variables_group.yaml :language: yaml

.. seealso::

:ref:intro_inventory Learn more about inventories in YAML or INI format. :ref:variables_in_inventory Find out more about inventory variables and their syntax. :ref:vault Find out how to encrypt sensitive content in your inventory such as passwords and keys.