Building and testing Python

Note: GitHub-hosted runners are not currently supported on GitHub Enterprise Server. You can see more information about planned future support on the GitHub public roadmap.

Introduction

This guide shows you how to build, test, and publish a Python package.

GitHub-hosted runners have a tools cache with pre-installed software, which includes Python and PyPy. You don't have to install anything! For a full list of up-to-date software and the pre-installed versions of Python and PyPy, see "Specifications for GitHub-hosted runners".

Prerequisites

You should be familiar with YAML and the syntax for GitHub Actions. For more information, see "Learn GitHub Actions."

We recommend that you have a basic understanding of Python, PyPy, and pip. For more information, see:

Using self-hosted runners on GitHub Enterprise Server

When using setup actions (such as actions/setup-LANGUAGE) on GitHub Enterprise Server with self-hosted runners, you might need to set up the tools cache on runners that do not have internet access. For more information, see "Setting up the tool cache on self-hosted runners without internet access."

Using the Python starter workflow

GitHub provides a Python starter workflow that should work for most Python projects. This guide includes examples that you can use to customize the starter workflow. For more information, see the Python starter workflow.

To get started quickly, add the starter workflow to the .github/workflows directory of your repository.

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: ["3.7", "3.8", "3.9", "3.10"]

    steps:
      - uses: actions/checkout@v2
      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v2
        with:
          python-version: ${{ matrix.python-version }}
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install flake8 pytest
          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
      - name: Lint with flake8
        run: |
          # stop the build if there are Python syntax errors or undefined names
          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
          # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
          flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
      - name: Test with pytest
        run: |
          pytest

Specifying a Python version

To use a pre-installed version of Python or PyPy on a GitHub-hosted runner, use the setup-python action. This action finds a specific version of Python or PyPy from the tools cache on each runner and adds the necessary binaries to PATH, which persists for the rest of the job. If a specific version of Python is not pre-installed in the tools cache, the setup-python action will download and set up the appropriate version from the python-versions repository.

Using the setup-python action is the recommended way of using Python with GitHub Actions because it ensures consistent behavior across different runners and different versions of Python. If you are using a self-hosted runner, you must install Python and add it to PATH. For more information, see the setup-python action.

The table below describes the locations for the tools cache in each GitHub-hosted runner.

	Ubuntu	Mac	Windows
Tool Cache Directory	`/opt/hostedtoolcache/*`	`/Users/runner/hostedtoolcache/*`	`C:\hostedtoolcache\windows\*`
Python Tool Cache	`/opt/hostedtoolcache/Python/*`	`/Users/runner/hostedtoolcache/Python/*`	`C:\hostedtoolcache\windows\Python\*`
PyPy Tool Cache	`/opt/hostedtoolcache/PyPy/*`	`/Users/runner/hostedtoolcache/PyPy/*`	`C:\hostedtoolcache\windows\PyPy\*`

If you are using a self-hosted runner, you can configure the runner to use the setup-python action to manage your dependencies. For more information, see using setup-python with a self-hosted runner in the setup-python README.

GitHub supports semantic versioning syntax. For more information, see "Using semantic versioning" and the "Semantic versioning specification."

Using multiple Python versions

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      # You can use PyPy versions in python-version.
      # For example, pypy2 and pypy3
      matrix:
        python-version: ["2.7", "3.7", "3.8", "3.9", "3.10"]

    steps:
      - uses: actions/checkout@v2
      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v2
        with:
          python-version: ${{ matrix.python-version }}
      # You can test your matrix by printing the current Python version
      - name: Display Python version
        run: python -c "import sys; print(sys.version)"

Using a specific Python version

You can configure a specific version of python. For example, 3.9. Alternatively, you can use semantic version syntax to get the latest minor release. This example uses the latest minor release of Python 3.

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v2
      - name: Set up Python 3.x
        uses: actions/setup-python@v2
        with:
          # Semantic version range syntax or exact version of a Python version
          python-version: '3.x'
          # Optional - x64 or x86 architecture, defaults to x64
          architecture: 'x64'
      # You can test your matrix by printing the current Python version
      - name: Display Python version
        run: python -c "import sys; print(sys.version)"

Excluding a version

If you specify a version of Python that is not available, setup-python fails with an error such as: ##[error]Version 3.4 with arch x64 not found. The error message includes the available versions.

You can also use the exclude keyword in your workflow if there is a configuration of Python that you do not wish to run. For more information, see "Workflow syntax for GitHub Actions."

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
        python-version: ["3.7", "3.8", "3.9", "3.10", pypy2, pypy3]
        exclude:
          - os: macos-latest
            python-version: "3.7"
          - os: windows-latest
            python-version: "3.7"

Using the default Python version

We recommend using setup-python to configure the version of Python used in your workflows because it helps make your dependencies explicit. If you don't use setup-python, the default version of Python set in PATH is used in any shell when you call python. The default version of Python varies between GitHub-hosted runners, which may cause unexpected changes or use an older version than expected.

GitHub-hosted runner	Description
Ubuntu	Ubuntu runners have multiple versions of system Python installed under `/usr/bin/python` and `/usr/bin/python3`. The Python versions that come packaged with Ubuntu are in addition to the versions that GitHub installs in the tools cache.
Windows	Excluding the versions of Python that are in the tools cache, Windows does not ship with an equivalent version of system Python. To maintain consistent behavior with other runners and to allow Python to be used out-of-the-box without the `setup-python` action, GitHub adds a few versions from the tools cache to `PATH`.
macOS	The macOS runners have more than one version of system Python installed, in addition to the versions that are part of the tools cache. The system Python versions are located in the `/usr/local/Cellar/python/*` directory.

Installing dependencies

GitHub-hosted runners have the pip package manager installed. You can use pip to install dependencies from the PyPI package registry before building and testing your code. For example, the YAML below installs or upgrades the pip package installer and the setuptools and wheel packages.

YAML

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 setuptools wheel

Requirements file

After you update pip, a typical next step is to install dependencies from requirements.txt. For more information, see pip.

YAML

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 -r requirements.txt

Testing your code

You can use the same commands that you use locally to build and test your code.

Testing with pytest and pytest-cov

This example installs or upgrades pytest and pytest-cov. Tests are then run and output in JUnit format while code coverage results are output in Cobertura. For more information, see JUnit and Cobertura.

YAML

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 -r requirements.txt
- name: Test with pytest
  run: |
    pip install pytest
    pip install pytest-cov
    pytest tests.py --doctest-modules --junitxml=junit/test-results.xml --cov=com --cov-report=xml --cov-report=html

Using Flake8 to lint code

The following example installs or upgrades flake8 and uses it to lint all files. For more information, see Flake8.

YAML

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 -r requirements.txt
- name: Lint with flake8
  run: |
    pip install flake8
    flake8 .
  continue-on-error: true

The linting step has continue-on-error: true set. This will keep the workflow from failing if the linting step doesn't succeed. Once you've addressed all of the linting errors, you can remove this option so the workflow will catch new issues.

Running tests with tox

With GitHub Actions, you can run tests with tox and spread the work across multiple jobs. You'll need to invoke tox using the -e py option to choose the version of Python in your PATH, rather than specifying a specific version. For more information, see tox.

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      matrix:
        python: ["3.8", "3.9", "3.10"]

    steps:
      - uses: actions/checkout@v2
      - name: Setup Python
        uses: actions/setup-python@v2
        with:
          python-version: ${{ matrix.python }}
      - name: Install tox and any other packages
        run: pip install tox
      - name: Run tox
        # Run tox using the version of Python in `PATH`
        run: tox -e py

Packaging workflow data as artifacts

You can upload artifacts to view after a workflow completes. For example, you may need to save log files, core dumps, test results, or screenshots. For more information, see "Persisting workflow data using artifacts."

The following example demonstrates how you can use the upload-artifact action to archive test results from running pytest. For more information, see the upload-artifact action.

YAML

name: Python package

on: [push]

jobs:
  build:

    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: ["3.7", "3.8", "3.9", "3.10"]

    steps:
      - uses: actions/checkout@v2
      - name: Setup Python # Set Python version
        uses: actions/setup-python@v2
        with:
          python-version: ${{ matrix.python-version }}
      # Install pip and pytest
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install pytest
      - name: Test with pytest
        run: pytest tests.py --doctest-modules --junitxml=junit/test-results-${{ matrix.python-version }}.xml
      - name: Upload pytest test results
        uses: actions/upload-artifact@v2
        with:
          name: pytest-results-${{ matrix.python-version }}
          path: junit/test-results-${{ matrix.python-version }}.xml
        # Use always() to always run this step to publish test results when there are test failures
        if: ${{ always() }}

Publishing to package registries

You can configure your workflow to publish your Python package to a package registry once your CI tests pass. This section demonstrates how you can use GitHub Actions to upload your package to PyPI each time you publish a release.

For this example, you will need to create two PyPI API tokens. You can use secrets to store the access tokens or credentials needed to publish your package. For more information, see "Creating and using encrypted secrets."

YAML

# This workflow uses actions that are not certified by GitHub.
# They are provided by a third-party and are governed by
# separate terms of service, privacy policy, and support
# documentation.

name: Upload Python Package

on:
  release:
    types: [published]

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 build
      - name: Build package
        run: python -m build
      - name: Publish package
        uses: pypa/gh-action-pypi-publish@27b31702a0e7fc50959f5ad993c78deac1bdfc29
        with:
          user: __token__
          password: ${{ secrets.PYPI_API_TOKEN }}

For more information about the starter workflow, see python-publish.

In this article

Introduction

Prerequisites

Using self-hosted runners on GitHub Enterprise Server

Using the Python starter workflow

Specifying a Python version

Using multiple Python versions

Using a specific Python version

Excluding a version

Using the default Python version

Installing dependencies

Requirements file

Testing your code

Testing with pytest and pytest-cov

Using Flake8 to lint code

Running tests with tox

Packaging workflow data as artifacts

Publishing to package registries