Using Astral’s uv Pyhon packager in Azure Web Apps GitHub Actions

I will eventually have to write a more detailed post about Astral’s uv, a tool that all the cool kids are using.

In summary, it’s a single tool that replaces a lot of different tools that we use to develop and distribute Python software. It can replace pip, pip-tools, pipx, poetry, pyenv, twine, and virtualenv. It’s also very fast.

For now, I just want to show how to integrate uv in a GitHub Actions workflow that deploys to Azure Web Apps.

A typical Azure Web Apps workflow

Azure Web Apps know how to work with Python repositories that contain a requirements.txt file. If you’re building a Python app with Django, Flask or FastAPI and deploying it to an Azure Web App, you probably have a GitHub Actions workflow YAML that has a build step that looks like this, under the .github/workflows directory of your repository:

  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - name: Set up Python version
        uses: actions/setup-python@v5
        with:
          python-version: '3.12'

      - name: Create and start virtual environment
        run: |
          python -m venv venv
          source venv/bin/activate
      
      - name: Install dependencies
        run: pip install -r requirements.txt
        
      - name: Zip artifact for deployment
        run: zip release.zip ./* -r

As you can see, this workflow checks out the repository, sets up Python 3.12, creates a virtual environment, installs the dependencies as listed in requirements.txt, zips the artifact and uploads it to the GitHub Actions runner.

If you have been using uv, you know that you don’t need to manually create a virtual environment, and you don’t need to list your dependencies in a requirements.txt file. You can do this locally with uv by exporting the dependencies with uv pip compile pyproject.toml -o requirements.txt, but that would add an extra step before checking in your code. Instead, we’re going to do this directly in the GitHub Actions runner.

Replacing the virtual environment and requirements.txt steps with uv

In order to use uv during the Azure build, you need to install uv in your GitHub Actions runner. You can delete the Create and start virtual environment and add the following code to install uv:

      - name: Install uv
        uses: astral-sh/setup-uv@v5

This will install uv in the GitHub Actions runner. The next step is to generate the requirements file. You can do this with the following command:

      - name: Generate requirements.txt
        run: uv pip compile pyproject.toml -o requirements.txt

Interestingly, deleting the Install dependencies step seems to have no effect at this point. If you need the packages during the build step, for example to perform tests, you shouldn’t delete them, but apparently the deploy step of the GitHub Actions workflow will install the dependencies from the requirements.txt file even if you don’t install them explicitly in the build step.

Just do it!

I have been using uv for the past few months, and I can tell that my producitivity improved. It’s easier to manage packages, to maintain installations, to install pytorch, and a lot easier to perform tests using multiple versions of Python using uv.

The only thing that was holding me back on using uv more was the lack of native integration with Azure Web Apps, but now that I have a workaround, I can’t see myself going back to the old way of doing things.

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