GitHub actions is a (relatively) novel GitHub feature that allows you to run code on GitHub when a predefined event is triggered. The most widespread use case for GitHub actions is for Continuous Integration, because it allows you to automatically test your code on any machine immediately after each push. For a great tutorial on how to use it for this see here.

But you can do so much more with them!! Basically you can set up any workflow to run after any event. An event is basically when a specific activity on GitHub happens, while a workflow is basically the script you want to run after the event has happened. For a full list of the events you can use see here. Workflow scripts are written in a .yml file and should be saved within the .github/worflows directory within your repository. I am incapable of writing a better tutorial for these than what is already on their documentation, but I will show a copy of a workflow script I recently put together and walk you through it.

In one of my previous blog posts I wrote about how to upload your code to PyPI. Hopefully I convinced you that this is quite easy, but it does require a few steps that you may not want to be doing every time you come up with a new feature (find a bug) and have to re-upload it. Luckily, you don’t have to!! Just stick the code into a GitHub actions workflow so it will automatically re-upload it for you. Here is the script I use for this:

name: Upload Python Package

on:
  release:
    types: [created]

jobs:
  deploy:

    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v2
    - name: Set up Python
      uses: actions/setup-python@v2
      with:
        python-version: '3.x'
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install setuptools wheel twine
    - name: Build and publish
      env:
        TWINE_USERNAME: __token__
        TWINE_PASSWORD: ${{ secrets.PYPI_TOKEN }}
      run: |
        python setup.py sdist bdist_wheel
        twine upload dist/*

I think these are relatively easy to read, but I will go through some parts in more detail.

on:
  release:

This means I am only running this script when there is a new release. I don’t want it to upload it to PyPI every time I push some changes but only when I release a new version. If you want to run the code after a different event here is what you would change in the script.

The python-version: '3.x' line just lets GitHub actions know to use the latest python release.

      env:
        TWINE_USERNAME: __token__
        TWINE_PASSWORD: ${{ secrets.PYPI_TOKEN }}

If you are uploading to PyPI you will need to provide some form of authentication. This can be done by creating a token and storing it as a GitHub secret. For more information on GitHub secrets see here.

And that is pretty much it!! If you got this far, I hope this was not a complete waste of your time.