deb-sahara/doc/source/devref/development.guidelines.rst
Vitaly Gridnev 8ceca6ce33 Add docs for event log usage
Add development documentation and useful notes for devs.

Change-Id: I380a9495e1b85bd73499b535323c87ce84e0ef62
2015-04-07 13:31:21 +03:00

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Development Guidelines
======================
Coding Guidelines
-----------------
For all the code in Sahara we have a rule - it should pass `PEP 8`_.
To check your code against PEP 8 run:
.. sourcecode:: console
$ tox -e pep8
.. note::
For more details on coding guidelines see file ``HACKING.rst`` in the root
of Sahara repo.
Modification of Upstream Files
------------------------------
We never modify upstream files in Sahara. Any changes in upstream files should be made
in the upstream project and then merged back in to Sahara. This includes whitespace
changes, comments, and typos. Any change requests containing upstream file modifications
are almost certain to receive lots of negative reviews. Be warned.
Examples of upstream files are default xml configuration files used to configure Hadoop, or
code imported from the OpenStack Oslo project. The xml files will usually be found in
``resource`` directories with an accompanying ``README`` file that identifies where the
files came from. For example:
.. sourcecode:: console
$ pwd
/home/me/sahara/sahara/plugins/vanilla/v2_3_0/resources
$ ls
core-default.xml hdfs-default.xml oozie-default.xml README.rst
create_oozie_db.sql mapred-default.xml post_conf.template yarn-default.xml
..
Testing Guidelines
------------------
Sahara has a suite of tests that are run on all submitted code,
and it is recommended that developers execute the tests themselves to
catch regressions early. Developers are also expected to keep the
test suite up-to-date with any submitted code changes.
Unit tests are located at ``sahara/tests``.
Sahara's suite of unit tests can be executed in an isolated environment
with `Tox`_. To execute the unit tests run the following from the root of
Sahara repo:
.. sourcecode:: console
$ tox -e py27
Documentation Guidelines
------------------------
All Sahara docs are written using Sphinx / RST and located in the main repo
in ``doc`` directory. You can add/edit pages here to update
http://docs.openstack.org/developer/sahara site.
The documentation in docstrings should follow the `PEP 257`_ conventions
(as mentioned in the `PEP 8`_ guidelines).
More specifically:
1. Triple quotes should be used for all docstrings.
2. If the docstring is simple and fits on one line, then just use
one line.
3. For docstrings that take multiple lines, there should be a newline
after the opening quotes, and before the closing quotes.
4. `Sphinx`_ is used to build documentation, so use the restructured text
markup to designate parameters, return values, etc. Documentation on
the sphinx specific markup can be found here:
Run the following command to build docs locally.
.. sourcecode:: console
$ tox -e docs
After it you can access generated docs in ``doc/build/`` directory, for example,
main page - ``doc/build/html/index.html``.
To make docs generation process faster you can use:
.. sourcecode:: console
$ SPHINX_DEBUG=1 tox -e docs
or to avoid sahara reinstallation to virtual env each time you want to rebuild
docs you can use the following command (it could be executed only after
running ``tox -e docs`` first time):
.. sourcecode:: console
$ SPHINX_DEBUG=1 .tox/docs/bin/python setup.py build_sphinx
.. note::
For more details on documentation guidelines see file HACKING.rst in the root
of Sahara repo.
.. _PEP 8: http://www.python.org/dev/peps/pep-0008/
.. _PEP 257: http://www.python.org/dev/peps/pep-0257/
.. _Tox: http://tox.testrun.org/
.. _Sphinx: http://sphinx.pocoo.org/markup/index.html
Event log Guidelines
--------------------
Currently Sahara keep with cluster useful information about provisioning.
Cluster provisioning can be represented as a linear series of provisioning
steps, which are executed one after another. Also each step would consist of
several events. The amount of events depends on the step and the amount of
instances in the cluster. Also each event can contain information about
cluster, instance, and node group. In case of errors, this event would contain
information about reasons of errors. Each exception in sahara contains a
unique identifier that will allow the user to find extra information about
the reasons for errors in the sahara logs. Here
http://developer.openstack.org/api-ref-data-processing-v1.1.html#v1.1eventlog
you can see an example of provisioning progress information.
This means that if you add some important phase for cluster provisioning to
sahara code, it's recommended to add new provisioning step for this phase.
It would allow users to use event log for handling errors during this phase.
Sahara already have special utils for operating provisioning steps and events
in module ``sahara/utils/cluster_progress_ops.py``.
.. note::
It's strictly recommended not use ``conductor`` event log ops directly
to assign events and operate provisioning steps.
.. note::
You should not add a new provisioning step until the previous step
successfully completed.
.. note::
It's strictly recommended to use ``event_wrapper`` for events handling