Jean-Philippe Evrard 68e3f202b4 [Docs] Restructure inventory documentation
The documentation of the inventory started to be spread out, but
also massive to be inside one page.

This moves it to the inventory section of the reference, but at the
same time, to improve readability, moves the previous content into
sub pages.

Change-Id: If2c6b83abafdc66879d818df4c9690142389a965
2018-04-09 09:44:45 +00:00

128 lines
4.3 KiB
ReStructuredText

Generating the Inventory
========================
The script that creates the inventory is located at
``inventory/dynamic_inventory.py``.
This section explains how ansible runs the inventory, and how
you can run it manually to see its behavior.
Executing the dynamic_inventory.py script manually
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When running an Ansible command (such as ``ansible``, ``ansible-playbook`` or
``openstack-ansible``) Ansible automatically executes the
``dynamic_inventory.py`` script
and use its output as inventory.
Run the following command:
.. code-block:: bash
# from the root folder of cloned OpenStack-Ansible repository
inventory/dynamic_inventory.py --config /etc/openstack_deploy/
This invocation is useful when testing changes to the dynamic inventory script.
Inputs
~~~~~~
The ``dynamic_inventory.py`` takes the ``--config`` argument for the directory
holding configuration from which to create the inventory. If not specified,
the default is ``/etc/openstack_deploy/``.
In addition to this argument, the base environment skeleton is provided in the
``inventory/env.d`` directory of the OpenStack-Ansible codebase.
Should an ``env.d`` directory be found in the directory specified by
``--config``, its contents will be added to the base environment, overriding
any previous contents in the event of conflicts.
.. note::
In all versions prior to |previous_release_formal_name|, this argument was ``--file``.
The following file must be present in the configuration directory:
* ``openstack_user_config.yml``
Additionally, the configuration or environment could be spread between two
additional sub-directories:
* ``conf.d``
* ``env.d`` (for environment customization)
The dynamic inventory script does the following:
* Generates the names of each container that runs a service
* Creates container and IP address mappings
* Assigns containers to physical hosts
As an example, consider the following excerpt from
``openstack_user_config.yml``:
.. code-block :: yaml
identity_hosts:
infra01:
ip: 10.0.0.10
infra02:
ip: 10.0.0.11
infra03:
ip: 10.0.0.12
The ``identity_hosts`` dictionary defines an Ansible inventory group named
``identity_hosts`` containing the three infra hosts. The configuration file
``inventory/env.d/keystone.yml`` defines additional Ansible
inventory groups for the containers that are deployed onto the three hosts
named with the prefix *infra*.
Note that any services marked with ``is_metal: true`` will run on the allocated
physical host and not in a container. For an example of ``is_metal: true``
being used refer to ``inventory/env.d/cinder.yml`` in the
``container_skel`` section.
For more details, see :ref:`configuring-inventory`.
Outputs
~~~~~~~
Once executed, the script will output an ``openstack_inventory.json`` file into
the directory specified with the ``--config`` argument. This is used as the
source of truth for repeated runs.
.. warning::
The ``openstack_inventory.json`` file is the source of truth for the
environment. Deleting this in a production environment means that the UUID
portion of container names will be regenerated, which then results in new
containers being created. Containers generated under the previous version
will no longer be recognized by Ansible, even if reachable via SSH.
The same JSON structure is printed to stdout, which is consumed by Ansible as
the inventory for the playbooks.
Checking inventory configuration for errors
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Using the ``--check`` flag when running ``dynamic_inventory.py`` will run the
inventory build process and look for known errors, but not write any files to
disk.
If any groups defined in the ``openstack_user_config.yml`` or ``conf.d`` files
are not found in the environment, a warning will be raised.
This check does not do YAML syntax validation, though it will fail if there
are unparseable errors.
Writing debug logs
~~~~~~~~~~~~~~~~~~~
The ``--debug/-d`` parameter allows writing of a detailed log file for
debugging the inventory script's behavior. The output is written to
``inventory.log`` in the current working directory.
The ``inventory.log`` file is appended to, not overwritten.
Like ``--check``, this flag is not invoked when running from ansible.