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

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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.

This directory is used to extend the environment skeleton, or modify the defaults defined in the playbooks/inventory/env.d directory.

See also Understanding Container Groups in Appendix H.

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.

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

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.

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.

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.

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.

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

- 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)

test_overrides:
  DEFAULT:
    new_item: 12345

Original template file "test.ini.j2"

[DEFAULT]
value1 = abc
value2 = 123

Rendered on disk file "/tmp/test.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:

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

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