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.. _CONTRIBUTING:
=================
How To Contribute
=================
Basics
======
#. Our source code is hosted on `OpenStack Kolla Git
<https://git.openstack.org/cgit/openstack/kolla/>`_. Bugs should be filed on
`launchpad <https://bugs.launchpad.net/kolla>`_.
#. Please follow OpenStack `Gerrit Workflow
<https://docs.openstack.org/infra/manual/developers.html#development-workflow>`__
to contribute to Kolla.
#. Note the branch you're proposing changes to. ``master`` is the current focus
of development. Kolla project has a strict policy of only allowing backports
in ``stable/branch``, unless when not applicable. A bug in a
``stable/branch`` will first have to be fixed in ``master``.
#. Please file a `blueprint of kolla <https://blueprints.launchpad.net/kolla>`__
for any significant code change and a bug
for any significant bug fix. See how to reference a bug or a blueprint in
the `commit message <https://wiki.openstack.org/wiki/GitCommitMessages>`_.
For simple changes, contributors may optionally add the text "TrivialFix" to
the commit message footer to indicate to reviewers a bug is not required.
Please use the existing sandbox repository, available at `sandbox
<https://git.openstack.org/cgit/openstack-dev/sandbox>`_,
for learning, understanding and testing the `Gerrit Workflow
<https://docs.openstack.org/infra/manual/developers.html#development-workflow>`_.
Adding a new service
====================
Kolla aims to both containerise and deploy all services within the OpenStack
"big tent". This is a constantly moving target as the ecosystem grows, so these
guidelines aim to help make adding a new service to Kolla a smooth experience.
The image
---------
Kolla follows `Best practices for writing Dockerfiles
<https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/>`__
when designing and implementing services where at all possible.
We use ``jinja2`` templating syntax to help manage the volume and complexity
that comes with maintaining multiple Dockerfiles for multiple different base
operating systems.
Images should be created under the ``docker`` directory. OpenStack services
should inherit from the provided ``openstack-base`` image, while supporting and
infrastructure services (for example, mongodb) should inherit from ``base``.
Services consisting of only one service should be placed in an image named the
same as that service, for example, ``horizon``. Services that consist of
multiple processes generally use a base image and child images, for example,
``glance-base``, ``glance-api``, and ``glance-registry``.
Jinja2 'blocks' are employed throughout the Dockerfile's to help operators
customise various stages of the build (refer to `Dockerfile Customisation
<https://docs.openstack.org/kolla/latest/admin/image-building.html#dockerfile-customisation>`__)
Some of these blocks are free form however, there are a subset that should be
common to every Dockerfile. The overall structure for a multi container service
is as follows:
.. code-block:: console
FROM {{ namespace }}/{{ image_prefix }}openstack-base:{{ tag }}
LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build_date }}"
{% block << service >>_header %}{% endblock %}
{% import "macros.j2" as macros with context %}
<< binary specific steps >>
<< source specific steps >>
<< common steps >>
{% block << service >>_footer %}{% endblock %}
{% block footer %}{% endblock %}
.. note::
The generic footer block ``{% block footer %}{% endblock %}`` should not be
included in base images (for example, glance-base).
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