contribute.rst

Contributing and feedback guidelines

There are many ways to contribute to Pelican. You can improve the documentation, add missing features, and fix bugs (or just report them). You can also help out by reviewing and commenting on existing issues.

Don't hesitate to fork Pelican and submit an issue or pull request on GitHub. When doing so, please consider the following guidelines.

Setting up the development environment

While there are many ways to set up one's development environment, the following instructions will utilize Pip and pdm. These tools facilitate managing virtual environments for separate Python projects that are isolated from one another, so you can use different packages (and package versions) for each.

Please note that Python is required for Pelican development.

(Optional) If you prefer to install pdm once for use with multiple projects, you can install it via:

curl -sSL https://pdm.fming.dev/install-pdm.py | python3 -

Point your web browser to the Pelican repository and tap the Fork button at top-right. Then clone the source for your fork and add the upstream project as a Git remote:

mkdir ~/projects
git clone https://github.com/YOUR_USERNAME/pelican.git ~/projects/pelican
cd ~/projects/pelican
git remote add upstream https://github.com/getpelican/pelican.git

While pdm can dynamically create and manage virtual environments, we're going to manually create and activate a virtual environment:

mkdir ~/virtualenvs && cd ~/virtualenvs
python3 -m venv pelican
source ~/virtualenvs/pelican/*/activate

Install the needed dependencies and set up the project:

python -m pip install invoke
invoke setup
python -m pip install -e ~/projects/pelican

Your local environment should now be ready to go!

Development

Once Pelican has been set up for local development, create a topic branch for your bug fix or feature:

git checkout -b name-of-your-bugfix-or-feature

Now you can make changes to Pelican, its documentation, and/or other aspects of the project.

Running the test suite

Each time you make changes to Pelican, there are two things to do regarding tests: check that the existing tests pass, and add tests for any new features or bug fixes. The tests are located in pelican/tests, and you can run them via:

invoke tests

(For more on Invoke, see invoke -l to list tasks, or https://pyinvoke.org for documentation.)

In addition to running the test suite, it is important to also ensure that any lines you changed conform to code style guidelines. You can check that via:

invoke lint

If code style violations are found in lines you changed, correct those lines and re-run the above lint command until they have all been fixed. You do not need to address style violations, if any, for code lines you did not touch.

After making your changes and running the tests, you may see a test failure mentioning that "some generated files differ from the expected functional tests output." If you have made changes that affect the HTML output generated by Pelican, and the changes to that output are expected and deemed correct given the nature of your changes, then you should update the output used by the functional tests. To do so, make sure you have both en_EN.utf8 and fr_FR.utf8 locales installed, and then run the following command:

invoke update-functional-tests

You may also find that some tests are skipped because some dependency (e.g., Pandoc) is not installed. This does not automatically mean that these tests have passed; you should at least verify that any skipped tests are not affected by your changes.

You should run the test suite under each of the supported versions of Python. This is best done by creating a separate Python environment for each version. Tox is a useful tool to automate running tests inside virtualenv environments.

Building the docs

If you make changes to the documentation, you should build and inspect your changes before committing them:

invoke docserve

Open http://localhost:8000 in your browser to review the documentation. While the above task is running, any changes you make and save to the documentation should automatically appear in the browser, as it live-reloads when it detects changes to the documentation source files.

Plugin development

To create a new Pelican plugin, please refer to the plugin template repository for detailed instructions.

If you want to contribute to an existing Pelican plugin, follow the steps above to set up Pelican for local development, and then create a directory to store cloned plugin repositories:

mkdir -p ~/projects/pelican-plugins

Assuming you wanted to contribute to the Simple Footnotes plugin, you would first browse to the Simple Footnotes repository on GitHub and tap the Fork button at top-right. Then clone the source for your fork and add the upstream project as a Git remote:

git clone https://github.com/YOUR_USERNAME/simple-footnotes.git ~/projects/pelican-plugins/simple-footnotes
cd ~/projects/pelican-plugins/simple-footnotes
git remote add upstream https://github.com/pelican-plugins/simple-footnotes.git

Install the needed dependencies and set up the project:

invoke setup

Create a topic branch for your plugin bug fix or feature:

git checkout -b name-of-your-bugfix-or-feature

After writing new tests for your plugin changes, run the plugin test suite and check for code style compliance via:

invoke tests
invoke lint

If style violations are found, many of them can be addressed automatically via:

invoke black
invoke isort

If style violations are found even after running the above auto-formatters, you will need to make additional manual changes until invoke lint no longer reports any code style violations.

Submitting your changes

Assuming linting validation and tests pass, add a RELEASE.md file in the root of the project that contains the release type (major, minor, patch) and a summary of the changes that will be used as the release changelog entry. For example:

Release type: patch

Fix browser reloading upon changes to content, settings, or theme

Commit your changes and push your topic branch:

git add .
git commit -m "Your detailed description of your changes"
git push origin name-of-your-bugfix-or-feature

Finally, browse to your repository fork on GitHub and submit a pull request.

Logging tips

Try to use logging with appropriate levels.

For logging messages that are not repeated, use the usual Python way:

# at top of file
import logging
logger = logging.getLogger(__name__)

# when needed
logger.warning("A warning with %s formatting", arg_to_be_formatted)

Do not format log messages yourself. Use %s formatting in messages and pass arguments to logger. This is important, because the Pelican logger will preprocess some arguments, such as exceptions.

Limiting extraneous log messages

If the log message can occur several times, you may want to limit the log to prevent flooding. In order to do that, use the extra keyword argument for the logging message in the following format:

logger.warning("A warning with %s formatting", arg_to_be_formatted,
    extra={'limit_msg': 'A generic message for too many warnings'})

Optionally, you can also set 'limit_args' as a tuple of arguments in extra dict if your generic message needs formatting.

Limit is set to 5, i.e, first four logs with the same 'limit_msg' are outputted normally but the fifth one will be logged using 'limit_msg' (and 'limit_args' if present). After the fifth, corresponding log messages will be ignored.

For example, if you want to log missing resources, use the following code:

for resource in resources:
    if resource.is_missing:
        logger.warning(
            'The resource %s is missing', resource.name,
            extra={'limit_msg': 'Other resources were missing'})

The log messages will be displayed as follows:

WARNING: The resource prettiest_cat.jpg is missing
WARNING: The resource best_cat_ever.jpg is missing
WARNING: The resource cutest_cat.jpg is missing
WARNING: The resource lolcat.jpg is missing
WARNING: Other resources were missing

Outputting traceback in the logs

If you're logging inside an except block, you may want to provide the traceback information as well. You can do that by setting exc_info keyword argument to True during logging. However, doing so by default can be undesired because tracebacks are long and can be confusing to regular users. Try to limit them to --debug mode like the following:

try:
    some_action()
except Exception as e:
    logger.error('Exception occurred: %s', e,
        exc_info=settings.get('DEBUG', False))