openstack-ansible/doc/source/developer-docs/extending.rst

`Home <index.html>`_ OpenStack-Ansible Developer Documentation

Extending OpenStack-Ansible
===========================

The OpenStack-Ansible project provides a basic OpenStack environment, but
many deployers will wish to extend the environment based on their needs. This
could include installing extra services, changing package versions, or
overriding existing variables.

Using these extension points, deployers can provide a more 'opinionated'
installation of OpenStack that may include their own software.

Including OpenStack-Ansible in your project
-------------------------------------------

Including the openstack-ansible repository within another project can be
done in several ways.

    1. A git submodule pointed to a released tag.
    2. A script to automatically perform a git checkout of
       openstack-ansible

When including OpenStack-Ansible in a project, consider using a parallel
directory structure as shown in the `ansible.cfg files`_ section.

Also note that copying files into directories such as `env.d`_ or
`conf.d`_ should be handled via some sort of script within the extension
project.

ansible.cfg files
-----------------

You can create your own playbook, variable, and role structure while still
including the OpenStack-Ansible roles and libraries by putting an
``ansible.cfg`` file in your ``playbooks`` directory.

The relevant options for Ansible 1.9 (included in OpenStack-Ansible)
are as follows:

    ``library``
        This variable should point to
        ``openstack-ansible/playbooks/library``. Doing so allows roles and
        playbooks to access OpenStack-Ansible's included Ansible modules.
    ``roles_path``
        This variable should point to
        ``openstack-ansible/playbooks/roles``. This allows Ansible to
        properly look up any OpenStack-Ansible roles that extension roles
        may reference.
    ``inventory``
        This variable should point to
        ``openstack-ansible/playbooks/inventory``. With this setting,
        extensions have access to the same dynamic inventory that
        OpenStack-Ansible uses.

Note that the paths to the ``openstack-ansible`` top level directory can be
relative in this file.

Consider this directory structure::

    my_project
    |
    |- custom_stuff
    |  |
    |  |- playbooks
    |- openstack-ansible
    |  |
    |  |- playbooks

The variables in ``my_project/custom_stuff/playbooks/ansible.cfg`` would use
``../openstack-ansible/playbooks/<directory>``.


env.d
-----

The ``/etc/openstack_deploy/env.d`` directory sources all YAML files into the
deployed environment, allowing a deployer to define additional group mappings.

See also `Understanding Container Groups`_ in Appendix H.

.. _Understanding Container Groups: ../install-guide/app-custom-layouts.html#understanding-container-groups

conf.d
------

Common OpenStack services and their configuration are defined by
OpenStack-Ansible in the
``/etc/openstack_deploy/openstack_user_config.yml`` settings file.

Additional services should be defined with a YAML file in
``/etc/openstack_deploy/conf.d``, in order to manage file size.

See also `Understanding Host Groups`_ in Appendix H.

.. _Understanding Host Groups: ../install-guide/app-custom-layouts.html#understanding-host-groups

user\_*.yml files
-----------------

Files in ``/etc/openstack_deploy`` beginning with ``user_`` will be automatically
sourced in any ``openstack-ansible`` command. Alternatively, the files can be
sourced with the ``-e`` parameter of the ``ansible-playbook`` command.

``user_variables.yml`` and ``user_secrets.yml`` are used directly by
OpenStack-Ansible. Adding custom variables used by your own roles and playbooks
to these files is not recommended. Doing so will complicate your upgrade path
by making comparison of your existing files with later versions of these files
more arduous. Rather, recommended practice is to place your own variables in files
named following the ``user_*.yml`` pattern so they will be sourced alongside
those used exclusively by OpenStack-Ansible.

Ordering and Precedence
+++++++++++++++++++++++

``user_*.yml`` variables are just YAML variable files. They will be sourced
in alphanumeric order by ``openstack-ansible``.

.. _adding-galaxy-roles:

Adding Galaxy roles
-------------------

Any roles defined in ``openstack-ansible/ansible-role-requirements.yml``
will be installed by the
``openstack-ansible/scripts/bootstrap-ansible.sh`` script.


Setting overrides in configuration files
----------------------------------------

All of the services that use YAML, JSON, or INI for configuration can receive
overrides through the use of a Ansible action plugin named ``config_template``.
The configuration template engine allows a deployer to use a simple dictionary
to modify or add items into configuration files at run time that may not have a
preset template option. All OpenStack-Ansible roles allow for this functionality
where applicable. Files available to receive overrides can be seen in the
``defaults/main.yml`` file as standard empty dictionaries (hashes).

Practical guidance for using this feature is available in the `Install Guide`_.

This module has been `submitted for consideration`_ into Ansible Core.

.. _Install Guide: ../install-guide/configure-openstack.html
.. _submitted for consideration: https://github.com/ansible/ansible/pull/12555


Build the environment with additional python packages
+++++++++++++++++++++++++++++++++++++++++++++++++++++

The system will allow you to install and build any package that is a python
installable. The repository infrastructure will look for and create any
git based or PyPi installable package. When the package is built the repo-build
role will create the sources as Python wheels to extend the base system and
requirements.

While the packages pre-built in the repository-infrastructure are comprehensive,
it may be needed to change the source locations and versions of packages to suit
different deployment needs. Adding additional repositories as overrides is as
simple as listing entries within the variable file of your choice. Any
``user_.*.yml`` file within the "/etc/openstack_deployment" directory will work
to facilitate the addition of a new packages.


.. code-block:: yaml

    swift_git_repo: https://private-git.example.org/example-org/swift
    swift_git_install_branch: master


Additional lists of python packages can also be overridden using a ``user_.*.yml``
variable file.

.. code-block:: yaml

    swift_requires_pip_packages:
      - virtualenv
      - virtualenv-tools
      - python-keystoneclient
      - NEW-SPECIAL-PACKAGE


Once the variables are set call the play ``repo-build.yml`` to build all of the
wheels within the repository infrastructure. When ready run the target plays to
deploy your overridden source code.


Module documentation
++++++++++++++++++++

These are the options available as found within the virtual module documentation
section.

.. code-block:: yaml

    module: config_template
    version_added: 1.9.2
    short_description: >
      Renders template files providing a create/update override interface
    description:
      - The module contains the template functionality with the ability to
        override items in config, in transit, through the use of a simple
        dictionary without having to write out various temp files on target
        machines. The module renders all of the potential jinja a user could
        provide in both the template file and in the override dictionary which
        is ideal for deployers who may have lots of different configs using a
        similar code base.
      - The module is an extension of the **copy** module and all of attributes
        that can be set there are available to be set here.
    options:
      src:
        description:
          - Path of a Jinja2 formatted template on the local server. This can
            be a relative or absolute path.
        required: true
        default: null
      dest:
        description:
          - Location to render the template to on the remote machine.
        required: true
        default: null
      config_overrides:
        description:
          - A dictionary used to update or override items within a configuration
            template. The dictionary data structure may be nested. If the target
            config file is an ini file the nested keys in the ``config_overrides``
            will be used as section headers.
      config_type:
        description:
          - A string value describing the target config type.
        choices:
          - ini
          - json
          - yaml


Example task using the "config_template" module
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: yaml

   - name: Run config template ini
     config_template:
       src: test.ini.j2
       dest: /tmp/test.ini
       config_overrides: {{ test_overrides }}
       config_type: ini


Example overrides dictionary(hash)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: yaml

   test_overrides:
     DEFAULT:
       new_item: 12345


Original template  file "test.ini.j2"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: ini

   [DEFAULT]
   value1 = abc
   value2 = 123


Rendered on disk file "/tmp/test.ini"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. code-block:: ini

   [DEFAULT]
   value1 = abc
   value2 = 123
   new_item = 12345


In this task the ``test.ini.j2`` file is a template which will be rendered and
written to disk at ``/tmp/test.ini``. The **config_overrides** entry is a
dictionary(hash) which allows a deployer to set arbitrary data as overrides to
be written into the configuration file at run time. The **config_type** entry
specifies the type of configuration file the module will be interacting with;
available options are "yaml", "json", and "ini".


Discovering Available Overrides
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

All of these options can be specified in any way that suits your deployment.
In terms of ease of use and flexibility it's recommended that you define your
overrides in a user variable file such as
``/etc/openstack_deploy/user_variables.yml``.

The list of overrides available may be found by executing:

.. code-block:: bash

    find . -name "main.yml" -exec grep '_.*_overrides:' {} \; \
        | grep -v "^#" \
        | sort -u

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