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Keepalived is not different than the rest, and it could use the group vars for its configuration. Change-Id: I3fbf9edd0c7e3c0771ea18c4022c9c3cda5ff99c
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==================================
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Contributing to Roles and Services
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==================================
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If you would like to contribute towards a role to introduce an OpenStack
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or infrastructure service, or to improve an existing role, the
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OpenStack-Ansible project would welcome that contribution and your assistance
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in maintaining it.
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Recommended procedure to develop a role
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---------------------------------------
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#. Deploy OpenStack-Ansible (possibly using
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`an AIO`_
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deploy) so that you have the rest of an OpenStack cluster to integrate with
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in your testing.
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#. Deploy your service on another VM, or possibly directly on the AIO host, by
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hand. Configure the service to coordinate with the OpenStack cluster
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appropriately. When all the related systems are communicating with each
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other you can use the resulting configuration as a reference later.
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#. Develop a role for your service. A recommended process is detailed below.
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.. _an AIO: quickstart-aio.html
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Writing a new role
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------------------
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Here are the steps to write the role:
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#. You can review roles which may be currently in development by checking our
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`specs repository`_ and `unmerged specs`_ on review.openstack.org. If you
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do not find a spec for the role, propose a blueprint/spec `(see also the
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spec template)`_ outlining the new Role. By proposing a draft spec you can
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help the OpenStack-Ansible community keep track of what roles are being
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developed and perhaps connect you with others who may be interested and
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able to help you in the process.
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#. Create a source repository (e.g. on Github) to start your work on the Role.
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#. Generate the reference directory structure for an Ansible role which is
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the necessary subset of the documented `Best Practice`_. You might use
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Ansible Galaxy tools to do this for you (e.g. ``ansible-galaxy init``).
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You may additionally want to include directories such as ``docs`` and
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``examples`` and ``tests`` for your role.
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#. Generate a meta/main.yml right away. This file is important to Ansible to
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ensure your dependent roles are installed and available and provides others
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with the information they will need to understand the purpose of your role.
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#. Develop task files for each of the install stages in turn, creating any
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handlers and templates as needed. Ensure that you notify handlers after any
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task which impacts the way the service would run (such as configuration
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file modifications). Also take care that file ownership and permissions are
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appropriate.
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.. HINT:: Fill in variable defaults, libraries, and prerequisites as you
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discover a need for them. You can also develop documentation for your
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role at the same time.
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#. Add tests to the role.
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#. Ensuring the role deploys with an AIO.
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Writing tasks in a role
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^^^^^^^^^^^^^^^^^^^^^^^
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Most OpenStack services will follow a common series of stages to install or
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update a service deployment. This is apparent when you review `tasks/main.yml`
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for existing roles.
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#. pre-install: prepare the service user group and filesystem directory paths
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on the host or container
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#. install: install system packages, prepare the (optional) service virtual
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environment, install service and requirements (into a virtual environment)
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#. post-install: apply all configuration files
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#. service add: register the service (each of: service type, service project,
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service user, and endpoints) within Keystone's service catalog.
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#. service setup: install a service-startup script (init, upstart, systemd,
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etc.) so that the service will start up when the container or host next
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starts.
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#. service init/startup: signal to the host or container to start the services,
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make sure the service runs on boot.
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There may be other specialized steps required by some services but most of the
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roles will perform all of these at a minimum. Begin by reviewing a role for a
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service that has something in common with your service and think about how you
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can fit most of the common service setup and configuration steps into that
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model.
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.. HINT:: Following the patterns you find in other roles can help ensure your role
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is easier to use and maintain.
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.. _(see also the spec template): https://git.openstack.org/cgit/openstack/openstack-ansible-specs/tree/specs/templates/template.rst
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.. _specs repository: https://git.openstack.org/cgit/openstack/openstack-ansible-specs
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.. _unmerged specs: https://review.openstack.org/#/q/status:+open+project:openstack/openstack-ansible-specs
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.. _Best Practice: https://docs.ansible.com/ansible/playbooks_best_practices.html#directory-layout
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Keep in mind a role candidate for inclusion should respect our
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`Ansible Style Guide`_.
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.. _Ansible Style Guide: contribute.html#ansible-style-guide
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Adding tests to a role
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^^^^^^^^^^^^^^^^^^^^^^
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Each of the role tests is in its tests/ folder.
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This folder contains at least the following files:
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#. ``test.yml`` ("super" playbook acting as test router to sub-playbooks)
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#. ``<role name>-overrides.yml``. This var file is automatically loaded
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by our shell script in our `tests repository`_.
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#. ``inventory``. A static inventory for role testing.
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It's possible some roles have multiple inventories. See for example the
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neutron role with its ``lxb_inventory``, ``calico_inventory``.
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#. ``group_vars`` and ``host_vars``. These folders will hold override the
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necessary files for testing. For example, this is where you override
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the IP addresses, IP ranges, and ansible connection details.
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#. ``ansible-role-requirements.yml``. This should be fairly straightforward:
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this file contains all the roles to clone before running your role.
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The roles' relative playbooks will have to be listed in the ``test.yml``
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file. However, keep in mind to NOT re-invent the wheel. For example,
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if your role needs keystone, you don't need to create your own keystone
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install playbook, because we have a generic keystone install playbook
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in the `tests repository`.
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.. _tests repository: https://git.openstack.org/cgit/openstack/openstack-ansible-tests
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Deploying the role
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^^^^^^^^^^^^^^^^^^
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#. Include your role on the deploy host. See also `Adding Galaxy roles`_.
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#. Perform any other host preparation (such as the tasks performed by the
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``bootstrap-aio.yml`` playbook). This includes any preparation tasks that
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are particular to your service.
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#. Generate files to include your service in the Ansible inventory
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using `env.d`_ and `conf.d`_ files for use on your deploy host.
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.. HINT:: You can follow examples from other roles, making the appropriate
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modifications being sure that group labels in ``env.d`` and ``conf.d``
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files are consistent.
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#. Generate secrets, if any, as described in the :deploy_guide:`Configure
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Service Credentials <configure.html#configuring-service-credentials>`.
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You can append your keys to an existing ``user_secrets.yml`` file or add a
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new file to the ``openstack_deploy`` directory to contain them. Provide
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overrides for any other variables you will need at this time as well, either
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in ``user_variables.yml`` or another file. This is explained in more depth
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under `Extending OpenStack-Ansible`_.
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#. If your service is installed from source or relies on python packages which
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need to be installed from source, specify a repository for the source
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code of each requirement by adding a file to your deploy host under
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``playbooks/defaults/repo_packages`` in the OpenStack-Ansible source
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repository and following the pattern of files currently in that directory.
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You could also simply add an entry to an existing file there. Be sure to
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run the ``repo-build.yml`` play later so that wheels for your packages will
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be included in the repository infrastructure.
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#. Make any required adjustments to the load balancer configuration
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(e.g. modify ``playbooks/inventory/group_vars/all/haproxy.yml`` in the
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OpenStack-Ansible source repository on your deploy host) so that your
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service can be reached through a load balancer, if appropriate, and be sure
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to run the ``haproxy-install.yml`` play later so your changes will be
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applied. Please note, you can also use ``haproxy_extra_services`` variable
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if you don't want to provide your service as default for everyone.
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#. Put together a service install playbook file for your role. This can also
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be modeled from any existing service playbook that has similar
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dependencies to your service (database, messaging, storage drivers,
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container mount points, etc.). A common place to keep playbook files in a
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Galaxy role is in an ``examples`` directory off the root of the role.
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.. HINT:: If you adhere to the pattern of isolating your role's extra
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deployment requirements (secrets and var files, HAProxy yml fragments,
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repo_package files, etc.) in their own files it makes it easy for you to
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automate these additional steps when testing your role.
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.. _Adding Galaxy roles: extending.html#adding-galaxy-roles
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.. _env.d: extending.html#env-d
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.. _conf.d: extending.html#conf-d
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.. _Extending OpenStack-Ansible: extending.html#user-yml-files
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Role development maturity
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-------------------------
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In order to include a role into the integrated build implemented by the
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playbooks in the ``openstack/openstack-ansible`` repository, it needs to
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meet an appropriate level of maturity requirements. Developers are
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encouraged to observe the below-mentioned patterns in the existing roles.
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.. note::
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Many of the existing roles may not fully implement all the patterns
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just yet. It is important to look through multiple roles to get an
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idea of the common patterns rather than to fixate on a single role's
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pattern. Another good place to look is `role maturity table`_.
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.. _role maturity table: role-maturity.html
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The development of a role will usually go through the following stages:
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#. Initial role development
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* Include base scaffolding. To facilitate development and the tests
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implemented across all OpenStack-Ansible roles, a base set of folders
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and files need to be implemented. A base set of configuration and test
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facilitation scripts must include at least the following:
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* ``tox.ini``:
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The lint testing, documentation build, release notes build and
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functional build execution process for the role's gate tests are all
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defined in this file.
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* ``test-requirements.txt``:
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The python requirements which must be installed when executing the
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tests.
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* ``other-requirements.txt``:
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The binary requirements which must be installed on the host the tests
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are executed on for the python requirements and the tox execution to
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work.
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* ``setup.cfg`` and ``setup.py``:
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Information about the repository which is used during the build of any
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artifacts.
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* ``run_tests.sh``:
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A convenient script for developers to execute all standard tests on a
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suitable host.
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* ``Vagrantfile``:
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A convenient configuration file to allow a developer to easily create a
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test virtual machine using `Vagrant`_. This must automatically execute
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``run_tests.sh``.
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* ``README.rst``, ``LICENSE``, ``CONTRIBUTING.rst``:
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A set of standard files which have content describing their purpose.
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* ``.gitignore``:
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A standard git configuration file for the repository which should be
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pretty uniform across all the repositories.
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* ``.gitreview``:
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A standard file configured for the project to inform the ``git-review``
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plugin where to find the upstream gerrit remote for the repository.
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* The role development should initially be focused on implementing a set of
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tasks and a test playbook which converge. The convergence must:
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* Implement ``developer_mode`` to build from a git source into a Python
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venv.
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* Deploy the applicable configuration files in the right places.
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* Ensure that the service starts.
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The convergence may involve consuming other OpenStack-Ansible roles (For
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example: ``galera_server``, ``galera_client``, ``rabbitmq_server``) in
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order to ensure that the appropriate infrastructure is in place. Reuse
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of existing roles in OpenStack-Ansible or Ansible Galaxy is strongly
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encouraged.
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* The role *must* support Ubuntu 16.04 LTS. It should
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ideally also support CentOS7 but this is not required at this time. The
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patterns to achieve this include:
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* The separation of platform specific variables into role vars files.
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* The detection and handling of different init systems (init.d, SystemD).
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* The detection and handling of different package managers (apt, yum).
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* The detection and handling of different network configuration methods.
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There are several examples of these patterns implemented across many of
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the OpenStack-Ansible roles. Developers are advised to inspect the
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established patterns and either implement or improve upon them.
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* The role implementation should be done in such a way that it is agnostic
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with regards to whether it is implemented in a container, or on a
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physical host. The test infrastructure may make use of LXC containers for
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the separation of services, but if a role is used by a playbook that
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targets a host, it must work regardless of whether that host is a
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container, a virtual server, or a physical server. The use of LXC
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containers for role tests is not required but it may be useful in order
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to simulate a multi-node build out as part of the testing infrastructure.
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* Any secrets (For example: passwords) should not be provided with default
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values in the tasks, role vars, or role defaults. The tasks should be
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implemented in such a way that any secrets required, but not provided,
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should result in the task execution failure. It is important for a
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secure-by-default implementation to ensure that an environment is not
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vulnerable due to the production use of default secrets. Deployers
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must be forced to properly provide their own secret variable values.
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* Once the initial convergence is working and the services are running,
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the role development should focus on implementing some level of
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functional testing. Ideally, the functional tests for an OpenStack role
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should make use of Tempest to execute the functional tests. The ideal
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tests to execute are scenario tests as they test the functions that
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the service is expected to do in a production deployment. In the absence
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of any scenario tests for the service a fallback option is to implement
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the smoke tests instead.
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* The role must include documentation. The `Documentation and Release Note
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Guidelines`_ provide specific guidelines with regards to style and
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conventions. The documentation must include a description of the
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mandatory infrastructure (For example: a database and a message queue are
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required), variables (For example: the database name and credentials) and
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group names (For example: The role expects a group named ``foo_all`` to
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be present and it expects the host to be a member of it) for the role's
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execution to succeed.
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.. _Documentation and Release Note Guidelines: contribute.html#documentation-and-release-note-guidelines
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.. _Vagrant: https://www.vagrantup.com/
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#. Integration development
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Once the role has implemented the above requirements, work can begin on
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integrating the role into the integrated build. This involves the
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preparation of the following items:
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* Host and container group configuration
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This is implemented into the dynamic inventory through the definition of
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content in an ``env.d`` file. A description of how these work can be
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found in :deploy_guide:`Appendix C <app-custom-layouts.html>`
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of the Deployment Guide.
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* Load balancer configuration
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OpenStack-Ansible deploys services in a highly available configuration by
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default, so all API services must be configured for implementation behind
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HAProxy. This is done through the modification of
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``playbooks/vars/configs/haproxy_config.yml``.
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* Install playbook
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In order to implement the role in the appropriate way, an
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``os-<service>-install.yml`` playbook must be created and targeted
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at the appropriate group defined in the service ``env.d`` file. The
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playbook should also ensure that the database(s), database user(s),
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rabbitmq vhost and rabbitmq user are setup for the service. It is
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crucial that the implementation of the service is optional and that the
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deployer must opt-in to the deployment through the population of a host
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in the applicable host group. If the host group has no hosts, Ansible
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skips the playbook's tasks automatically.
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* Secrets
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Any secrets required for the role to work must be noted in the
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``etc/openstack_deploy/user_secrets.yml`` file.
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* Group vars
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Any variables needed by other roles to connect to the new role, or by the
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new role to connect to other roles, should be implemented in
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``playbooks/inventory/group_vars``. The group vars are essentially the
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glue which playbooks use to ensure that all roles are given the
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appropriate information. When group vars are implemented it should be a
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minimum set to achieve the goal of integrating the new role into the
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integrated build.
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* Documentation
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Content must be added to the Installation Guide to describe how to
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implement the new service in an integrated environment. This content must
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adhere to the `Documentation and Release Note Guidelines`_. Until the
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role has integrated functional testing implemented, the documentation
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must make it clear that the service inclusion in OpenStack-Ansible is
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experimental and is not fully tested by OpenStack-Ansible in an
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integrated build.
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* Release note
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A feature release note must be added to announce the new service
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availability and to refer to the Installation Guide entry and the role
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documentation for further details. This content must adhere to the
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`Documentation and Release Note Guidelines`_.
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* Integration test
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It must be possible to execute a functional, integrated test which
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executes a deployment in the same way as a production environment. The
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test must execute a set of functional tests using Tempest. This is the
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required last step before a service can remove the experimental warning
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from the documentation.
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