Contributing Guide

First and foremost, thank you for wanting to contribute! It’s the only way open source works!

Before you dive into writing patches, here are some of the basics:

Making Contributions

Getting Started

We’ll start by assuming you’ve got a working checkout of the repository (if not then please see the Horizon Quickstart).

Second, you’ll need to take care of a couple administrative tasks:

  1. Create an account on Launchpad.
  2. Sign the OpenStack Contributor License Agreement and follow the associated instructions to verify your signature.
  3. Join the Horizon Developers team on Launchpad.
  4. Follow the instructions for setting up git-review in your development environment.

Whew! Got that all that? Okay! You’re good to go.

Ways To Contribute

The easiest way to get started with Horizon’s code is to pick a bug on Launchpad that interests you, and start working on that. Alternatively, if there’s an OpenStack API feature you would like to see implemented in Horizon feel free to try building it.

If those are too big, there are lots of great ways to get involved without plunging in head-first:

  • Report bugs, triage new tickets, and review old tickets on the bug tracker.
  • Propose ideas for improvements via Launchpad Blueprints, via the mailing list on the project page, or on IRC.
  • Write documentation!
  • Write unit tests for untested code!

Choosing Issues To Work On

In general, if you want to write code, there are three cases for issues you might want to work on:

  1. Confirmed bugs
  2. Approved blueprints (features)
  3. New bugs you’ve discovered

If you have an idea for a new feature that isn’t in a blueprint yet, it’s a good idea to write the blueprint first so you don’t end up writing a bunch of code that may not go in the direction the community wants.

For bugs, open the bug first, but if you can reproduce the bug reliably and identify its cause then it’s usually safe to start working on it. However, getting independent confirmation (and verifying that it’s not a duplicate) is always a good idea if you can be patient.

After You Write Your Patch

Once you’ve made your changes, there are a few things to do:

  • Make sure the unit tests pass: ./run_tests.sh
  • Make sure PEP8 is clean: ./run_tests.sh --pep8
  • Make sure your code is up-to-date with the latest master: git pull --rebase
  • Finally, run git review to upload your changes to Gerrit for review.

The Horizon core developers will be notified of the new review and will examine it in a timely fashion, either offering feedback or approving it to be merged. If the review is approved, it is sent to Jenkins to verify the unit tests pass and it can be merged cleanly. Once Jenkins approves it, the change will be merged to the master repository and it’s time to celebrate!

Etiquette

The community’s guidelines for etiquette are fairly simple:

  • Treat everyone respectfully and professionally.
  • If a bug is “in progress” in the bug tracker, don’t start working on it without contacting the author. Try on IRC, or via the launchpad email contact link. If you don’t get a response after a reasonable time, then go ahead. Checking first avoids duplicate work and makes sure nobody’s toes get stepped on.
  • If a blueprint is assigned, even if it hasn’t been started, be sure you contact the assignee before taking it on. These larger issues often have a history of discussion or specific implementation details that the assignee may be aware of that you are not.
  • Please don’t re-open tickets closed by a core developer. If you disagree with the decision on the ticket, the appropriate solution is to take it up on IRC or the mailing list.
  • Give credit where credit is due; if someone helps you substantially with a piece of code, it’s polite (though not required) to thank them in your commit message.

Code Style

Python

We follow PEP8 for all our Python code, and use pep8.py (available via the shortcut ./run_tests.sh --pep8) to validate that our code meets proper Python style guidelines.

Django

Additionally, we follow Django’s style guide for templates, views, and other miscellany.

JavaScript

As a project, Horizon adheres to code quality standards for our JavaScript just as we do for our Python. To that end we recommend (but do not strictly enforce) the use of JSLint to validate some general best practices.

The default options are mostly good, but the following accommodate some allowances we make:

  • Set Indentation to 2.
  • Enable the Assume console, alert, ... option.
  • Enable the Assume a browser option.
  • Enable the Tolerate missing 'use strict' pragma option.
  • Clear the Maximum number of errors field.
  • Add horizon,$ to the Predefined list.

We don’t require that everything works with JavaScript disabled. It’s fine to introduce features that require that JavaScript is enabled in the user’s web browser.

The code has to work on the stable versions of Firefox, Chrome, Safari, and Opera web browsers, and on Microsoft Internet Explorer 8 and later.

CSS

Style guidelines for CSS are currently quite minimal. Do your best to make the code readable and well-organized. Two spaces are preferred for indentation so as to match both the JavaScript and HTML files.

HTML

Again, readability is paramount; however be conscientious of how the browser will handle whitespace when rendering the output. Two spaces is the preferred indentation style to match all front-end code.

Documentation

Horizon’s documentation is written in reStructuredText and uses Sphinx for additional parsing and functionality, and should follow standard practices for writing reST. This includes:

  • Flow paragraphs such that lines wrap at 80 characters or less.
  • Use proper grammar, spelling, capitalization and punctuation at all times.
  • Make use of Sphinx’s autodoc feature to document modules, classes and functions. This keeps the docs close to the source.
  • Where possible, use Sphinx’s cross-reference syntax (e.g. :class:`~horizon.foo.Bar`) when referring to other Horizon components. The better-linked our docs are, the easier they are to use.

Be sure to generate the documentation before submitting a patch for review. Unexpected warnings often appear when building the documentation, and slight reST syntax errors frequently cause links or cross-references not to work correctly.

Conventions

Simply by convention, we have a few rules about naming:

  • The term “project” is used in place of Keystone’s “tenant” terminology in all user-facing text. The term “tenant” is still used in API code to make things more obvious for developers.
  • The term “dashboard” refers to a top-level dashboard class, and “panel” to the sub-items within a dashboard. Referring to a panel as a dashboard is both confusing and incorrect.