How to Contribute
How to Contribute#
Thank you for your interest in contributing to Pyodide! There are many ways to contribute, and we appreciate all of them. Here are some guidelines & pointers for diving into it.
To contribute code, see the following steps,
Fork the Pyodide repository https://github.com/pyodide/pyodide on Github.
If you are on Linux, you can skip this step. On Windows and MacOS you have a choice. The first option is to manually install Docker:
on MacOS follow these instructions
on Windows, install WSL 2, then Docker. Note that Windows filesystem access from WSL2 is very slow and should be avoided when building Pyodide.
The second option is to use a service that provides a Linux development environment, such as
Clone your fork of Pyodide
git clone https://github.com/<your-username>/pyodide.git
and add the upstream remote,
git remote add upstream https://github.com/pyodide/pyodide.git
While the build will happen inside Docker you still need a development environment with Python 3.10 and ideally Node.js. These can be installed for instance with,
conda create -c conda-forge -n pyodide-env python=3.10.2 nodejs conda activate pyodide-env
or via your system package manager.
Install requirements (it’s recommended to use a virtualenv or a conda env),
pip install -r requirements.txt
Enable pre-commit for code style,
This will run a set of linters for each commit.
Follow Building from sources instructions.
See Testing and benchmarking documentation.
Code of Conduct#
Pyodide has adopted a Code of Conduct that we expect all contributors and core members to adhere to.
Work on Pyodide happens on GitHub. Core members and contributors can make Pull Requests to fix issues and add features, which all go through the same review process. We’ll detail how you can start making PRs below.
We’ll do our best to keep
main in a non-breaking state, ideally with tests
always passing. The unfortunate reality of software development is sometimes
things break. As such,
main cannot be expected to remain reliable at all
times. We recommend using the latest stable version of Pyodide.
Pyodide follows semantic versioning - major versions for breaking changes (x.0.0), minor versions for new features (0.x.0), and patches for bug fixes (0.0.x).
We keep a file, docs/changelog.md, outlining changes to Pyodide in each release. We like to think of the audience for changelogs as non-developers who primarily run the latest stable. So the change log will primarily outline user-visible changes such as new features and deprecations, and will exclude things that might otherwise be inconsequential to the end user experience, such as infrastructure or refactoring.
Bugs & Issues#
We use Github Issues for announcing and discussing bugs and features. Use this link to report a bug or issue. We provide a template to give you a guide for how to file optimally. If you have the chance, please search the existing issues before reporting a bug. It’s possible that someone else has already reported your error. This doesn’t always work, and sometimes it’s hard to know what to search for, so consider this extra credit. We won’t mind if you accidentally file a duplicate report.
Core contributors are monitoring new issues & comments all the time, and will label & organize issues to align with development priorities.
How to Contribute#
Pull requests are the primary mechanism we use to change Pyodide. GitHub itself has some great documentation on using the Pull Request feature. We use the “fork and pull” model described here, where contributors push changes to their personal fork and create pull requests to bring those changes into the source repository.
Please make pull requests against the
If you’re looking for a way to jump in and contribute, our list of good first issues is a great place to start.
If you’d like to fix a currently-filed issue, please take a look at the comment thread on the issue to ensure no one is already working on it. If no one has claimed the issue, make a comment stating you’d like to tackle it in a PR. If someone has claimed the issue but has not worked on it in a few weeks, make a comment asking if you can take over, and we’ll figure it out from there.
We use pytest, driving Selenium as our testing framework. Every PR will automatically run through our tests, and our test framework will alert you on GitHub if your PR doesn’t pass all of them. If your PR fails a test, try to figure out whether or not you can update your code to make the test pass again, or ask for help. As a policy we will not accept a PR that fails any of our tests, and will likely ask you to add tests if your PR adds new functionality. Writing tests can be scary, but they make open-source contributions easier for everyone to assess. Take a moment and look through how we’ve written our tests, and try to make your tests match. If you are having trouble, we can help you get started on our test-writing journey.
All code submissions should pass
make lint. Python is checked with
C is checked against the Mozilla style in
Documentation is a critical part of any open source project, and we are very
welcome to any documentation improvements. Pyodide has a documentation written
in Markdown in the
docs/ folder. We use the
for parsing Markdown in sphinx. You may want to have a look at the
MyST syntax guide
when contributing, in particular regarding
Building the docs#
From the directory
docs, first install the Python dependencies with
pip install -r requirements-doc.txt. You also need to install JsDoc, which is a
node dependency. Install it with
sudo npm install -g jsdoc. Then to
build the docs run
make html. The built documentation will be in the
docs/_build/html. To view them, cd into
start a file server, for instance
It often happens that patches need to be migrated between different versions of upstream packages.
If patches fail to apply automatically, one solution can be to
Checkout the initial version of the upstream package in a separate repo, and create a branch from it.
Add existing patches with
git apply <path.path>
Checkout the new version of the upstream package and create a branch from it.
Cherry-pick patches to the new version,
git cherry-pick <commit-hash>
and resolve conflicts.
Ncommits as patches e.g.
git format-patch -<N> -N --no-stat HEAD -o <out_dir>
All contributions to Pyodide will be licensed under the Mozilla Public License 2.0 (MPL 2.0). This is considered a “weak copyleft” license. Check out the tl;drLegal entry for more information, as well as Mozilla’s MPL 2.0 FAQ if you need further clarification on what is and isn’t permitted.