setup-python/docs/advanced-usage.md

Table of contents

• Using python-version input
  • Specifying a Python version
  • Specifying a PyPy version
  • Matrix Testing
• Using python-version-file input
• Check latest version
• Caching packages data
• Environment variables and action's outputs
• Available versions of Python and PyPy
  • Python
  • PyPy
• Hosted tool cache
• Using setup-python with a self hosted runner
  • Windows
  • Linux
  • MacOS
• Using setup-python on GHES

Using python-version input

The python-version input is used to specify the required version of Python or PyPy.

Specifying a Python version

If there is a specific version of Python that you need and you don't want to worry about any potential breaking changes due to patch updates (going from 3.7.5 to 3.7.6 for example), you should specify the exact major, minor, and patch version (such as 3.7.5):

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
with:
  python-version: '3.7.5' 
- run: python my_script.py

• The only downside to this is that set up will take a little longer since the exact version will have to be downloaded if the exact version is not already installed on the runner due to more recent versions.
• MSI installers are used on Windows for this, so runs will take a little longer to set up vs MacOS and Linux.

You can specify only a major and minor version if you are okay with the most recent patch version being used:

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
with:
  python-version: '3.7' 
- run: python my_script.py

• There will be a single patch version already installed on each runner for every minor version of Python that is supported.
• The patch version that will be preinstalled, will generally be the latest and every time there is a new patch released, the older version that is preinstalled will be replaced.
• Using the most recent patch version will result in a very quick setup since no downloads will be required since a locally installed version Python on the runner will be used.

You can specify version with prerelease tag to download and set up an accurate pre-release version of Python:

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.11.0-alpha.1'
- run: python my_script.py

It's also possible to use x.y-dev syntax to download and set up the latest patch version of Python, alpha and beta releases included. (for specified major & minor versions):

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.11-dev'
- run: python my_script.py

You can also use several types of ranges that are specified in semver, for instance:

• hyphen ranges to download and set up the latest available version of Python (includes both pre-release and stable versions):

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.11.0-alpha - 3.11.0'
- run: python my_script.py

• x-ranges to specify the latest stable version of Python (for specified major version):

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.x'
- run: python my_script.py

Please refer to the Advanced range syntax section of the semver to check other available range syntaxes.

Specifying a PyPy version

The version of PyPy should be specified in the format pypy<python_version>[-v<pypy_version>] or pypy-<python_version>[-v<pypy_version>]. The -v<pypy_version> parameter is optional and can be skipped. The latest PyPy version will be used in this case.

pypy3.8 or pypy-3.8 # the latest available version of PyPy that supports Python 3.8
pypy2.7 or pypy-2.7 # the latest available version of PyPy that supports Python 2.7
pypy3.7-v7.3.3 or pypy-3.7-v7.3.3 # Python 3.7 and PyPy 7.3.3
pypy3.7-v7.x or pypy-3.7-v7.x # Python 3.7 and the latest available PyPy 7.x
pypy3.7-v7.3.3rc1 or pypy-3.7-v7.3.3rc1 # Python 3.7 and preview version of PyPy
pypy3.7-nightly or pypy-3.7-nightly # Python 3.7 and nightly PyPy

Download and set up PyPy:

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version:
        - 'pypy3.7' # the latest available version of PyPy that supports Python 3.7
        - 'pypy3.7-v7.3.3' # Python 3.7 and PyPy 7.3.3
    steps:
    - uses: actions/checkout@v3
    - uses: actions/setup-python@v4
      with:
        python-version: ${{ matrix.python-version }}
    - run: python my_script.py

More details on PyPy syntax can be found in the Available versions of PyPy section.

Matrix Testing

Using setup-python it's possible to use matrix syntax to install several versions of Python/PyPy:

jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: [ '2.x', '3.x', 'pypy2.7', 'pypy3.7', 'pypy3.8' ]
    name: Python ${{ matrix.python-version }} sample
    steps:
      - uses: actions/checkout@v3
      - name: Set up Python
        uses: actions/setup-python@v4
        with:
          python-version: ${{ matrix.python-version }}
          architecture: x64
      - run: python my_script.py

Exclude a specific Python version:

jobs:
  build:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
        python-version: ['2.7', '3.7', '3.8', '3.9', '3.10', 'pypy2.7', 'pypy3.8']
        exclude:
          - os: macos-latest
            python-version: '3.8'
          - os: windows-latest
            python-version: '3.6'
    steps:
      - uses: actions/checkout@v3
      - name: Set up Python
        uses: actions/setup-python@v4
        with:
          python-version: ${{ matrix.python-version }}
      - name: Display Python version
        run: python --version

Using python-version-file input

setup-python action has ability to read Python/PyPy version from a version file. python-version-file input is used for specifying path to the version file. If .python-version file doesn't exist, action will fail with error.

In case both python-version and python-version-file inputs are supplied, python-version-file input will be ignored due to its lower priority.

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version-file: '.python-version' # Read python version from a file .python-version
- run: python my_script.py

Check latest version

The check-latest flag defaults to false. Use the default or set check-latest to false if you prefer stability and if you want to ensure a specific Python/PyPy version is always used.

If check-latest is set to true, the action first checks if the cached version is the latest one. If the locally cached version is not the most up-to-date, a Python/PyPy version will then be downloaded. Set check-latest to true if you want the most up-to-date Python/PyPy version to always be used.

steps:
  - uses: actions/checkout@v3
  - uses: actions/setup-python@v3
    with:
      python-version: '3.7'
      check-latest: true
  - run: python my_script.py

Setting check-latest to true has performance implications as downloading Python/PyPy versions is slower than using cached versions.

Caching packages data

Caching pipenv dependencies:

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.9'
    cache: 'pipenv'
- name: Install pipenv
  run: curl https://raw.githubusercontent.com/pypa/pipenv/master/get-pipenv.py | python
- run: pipenv install

Caching poetry dependencies:

steps:
- uses: actions/checkout@v3
- name: Install poetry
  run: pipx install poetry
- uses: actions/setup-python@v4
  with:
    python-version: '3.9'
    cache: 'poetry'
- run: poetry install
- run: poetry run pytest

Using a list of file paths to cache dependencies

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.9'
    cache: 'pipenv'
    cache-dependency-path: |
      server/app/Pipfile.lock
      __test__/app/Pipfile.lock      
- name: Install pipenv
  run: curl https://raw.githubusercontent.com/pypa/pipenv/master/get-pipenv.py | python
- run: pipenv install

Using wildcard patterns to cache dependencies

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.9'
    cache: 'pip'
    cache-dependency-path: '**/requirements-dev.txt'
- run: pip install -r subdirectory/requirements-dev.txt

Using a list of wildcard patterns to cache dependencies

steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
  with:
    python-version: '3.10'
    cache: 'pip'
    cache-dependency-path: |
      **/setup.cfg
      **/requirements*.txt      
- run: pip install -e . -r subdirectory/requirements-dev.txt

Environment variables and action's outputs

Action's outputs

python-version

Using python-version output it's possible to get the installed by action Python/PyPy version. This output is useful when the input python-version given as a range (e.g. 3.8.0 - 3.10.0 ), but down in a workflow you need to operate with the exact installed version (e.g. 3.10.1).

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    - uses: actions/setup-python@v4
      id: cp310
      with:
        python-version: "3.8.0 - 3.10.0"
    - run: echo '${{ steps.cp310.outputs.python-version }}'

python-path

python-path output is available with the absolute path of the Python/PyPy interpreter executable if you need it:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    - uses: actions/setup-python@v4
      id: cp310
      with:
        python-version: "3.10"
    - run: pipx run --python '${{ steps.cp310.outputs.python-path }}' nox --version

cache-hit

cache-hit output is available with a boolean value that indicates whether a cache hit occured on the primary key:

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    - uses: actions/setup-python@v4
      id: cp310
      with:
        python-version: "3.8.0"
        cache: "poetry"
    - run: echo '${{ steps.cp310.outputs.cache-hit }}' # true if cache-hit occured on the primary key

Evironment variables

These environment variables become available after setup-python action execution:

Env.variable	Description
pythonLocation	Contains the absolute path to the folder where the requested version of Python or PyPy is installed
Python_ROOT_DIR	https://cmake.org/cmake/help/latest/module/FindPython.html#module:FindPython
Python2_ROOT_DIR	https://cmake.org/cmake/help/latest/module/FindPython2.html#module:FindPython2
Python3_ROOT_DIR	https://cmake.org/cmake/help/latest/module/FindPython2.html#module:FindPython3

Using update-environment flag

The update-environment flag defaults to true. With this setting, the action will add/update environment variables (e.g. PATH, PKG_CONFIG_PATH, pythonLocation) for Python/PyPy to just work out of the box.

If update-environment is set to false, the action will not add/update environment variables. This can prove useful if you want the only side-effect to be to ensure Python/PyPy is installed and rely on the python-path output to run executable. Such a requirement on side-effect could be because you don't want your composite action messing with your user's workflows.

 steps:
   - uses: actions/checkout@v3
   - uses: actions/setup-python@v4
     id: cp310
     with:
       python-version: '3.10'
       update-environment: false
   - run: ${{ steps.cp310.outputs.python-path }} my_script.py

Available versions of Python and PyPy

Python

setup-python is able to configure Python from two sources:

• Preinstalled versions of Python in the tool cache on GitHub-hosted runners.
  • For detailed information regarding the available versions of Python that are installed, see Supported software.
  • For every minor version of Python, expect only the latest patch to be preinstalled.
  • If 3.8.1 is installed for example, and 3.8.2 is released, expect 3.8.1 to be removed and replaced by 3.8.2 in the tool cache.
  • If the exact patch version doesn't matter to you, specifying just the major and minor version will get you the latest preinstalled patch version. In the previous example, the version spec 3.8 will use the 3.8.2 Python version found in the cache.
  • Use -dev instead of a patch number (e.g., 3.11-dev) to install the latest patch version release for a given minor version, alpha and beta releases included.
• Downloadable Python versions from GitHub Releases (actions/python-versions).
  • All available versions are listed in the version-manifest.json file.
  • If there is a specific version of Python that is not available, you can open an issue here

Note: Python versions used in this action are generated in the python-versions repository. For macOS and Ubuntu images python versions are built from the source code. For Windows the python-versions repository uses installation executable. For more information please refer to the python-versions repository.

PyPy

setup-python is able to configure PyPy from two sources:

• Preinstalled versions of PyPy in the tool cache on GitHub-hosted runners

  • For detailed information regarding the available versions of PyPy that are installed, see Supported software.
  • For the latest PyPy release, all versions of Python are cached.
  • Cache is updated with a 1-2 week delay. If you specify the PyPy version as pypy3.7 or pypy-3.7, the cached version will be used although a newer version is available. If you need to start using the recently released version right after release, you should specify the exact PyPy version using pypy3.7-v7.3.3 or pypy-3.7-v7.3.3.

• Downloadable PyPy versions from the official PyPy site.

  • All available versions that we can download are listed in versions.json file.
  • PyPy < 7.3.3 are not available to install on-flight.
  • If some versions are not available, you can open an issue in https://foss.heptapod.net/pypy/pypy/

Hosted tool cache

GitHub hosted runners have a tool cache that comes with a few versions of Python + PyPy already installed. This tool cache helps speed up runs and tool setup by not requiring any new downloads. There is an environment variable called RUNNER_TOOL_CACHE on each runner that describes the location of the tool cache with Python and PyPy installed. setup-python works by taking a specific version of Python or PyPy from this tool cache and adding it to PATH.

	Location
Tool cache Directory	RUNNER_TOOL_CACHE
Python tool cache	RUNNER_TOOL_CACHE/Python/*
PyPy tool cache	RUNNER_TOOL_CACHE/PyPy/*

GitHub virtual environments are set up in actions/virtual-environments. During the setup, the available versions of Python and PyPy are automatically downloaded, set up and documented.

• Tool cache setup for Ubuntu: Install-Toolset.ps1 Configure-Toolset.ps1
• Tool cache setup for Windows: Install-Toolset.ps1 Configure-Toolset.ps1

Using setup-python with a self hosted runner

Python distributions are only available for the same environments that GitHub Actions hosted environments are available for. If you are using an unsupported version of Ubuntu such as 19.04 or another Linux distribution such as Fedora, setup-python will not work. If you have a supported self-hosted runner and you would like to use setup-python, there are a few extra things you need to make sure are set up so that new versions of Python can be downloaded and configured on your runner.

Windows requirements

• Your runner needs to be running with administrator privileges so that the appropriate directories and files can be set up when downloading and installing a new version of Python for the first time.
• If your runner is configured as a service, make sure the account that is running the service has the appropriate write permissions so that Python can get installed. The default NT AUTHORITY\NETWORK SERVICE should be sufficient.
• You need 7zip installed and added to your PATH so that the downloaded versions of Python files can be extracted properly during first-time setup.
• MSI installers are used when setting up Python on Windows. A word of caution as MSI installers update registry settings.
• The 3.8 MSI installer for Windows will not let you install another 3.8 version of Python. If setup-python fails for a 3.8 version of Python, make sure any previously installed versions are removed by going to "Apps & Features" in the Settings app.

If you are experiencing problems while configuring Python on your self-hosted runner, turn on step debugging to see addition logs.

Using setup-python on GHES

setup-python comes pre-installed on the appliance with GHES if Actions is enabled. When dynamically downloading Python distributions, setup-python downloads distributions from actions/python-versions on github.com (outside of the appliance). These calls to actions/python-versions are made via unauthenticated requests, which are limited to 60 requests per hour per IP. If more requests are made within the time frame, then you will start to see rate-limit errors during download that read ##[error]API rate limit exceeded for....

To avoid hitting rate-limit problems, we recommend setting up your own runner tool cache.