GitHub Actions Matrix example using containers

ci.yml

# From https://github.com/altendky/alqtendpy/blob/b375b1d9189f125828fdabbf2d329e5b1d04ff21/.github/workflows/ci.yml

name: CI

on:
  push:
    branches:
      - master
    tags:
      - v*
  pull_request:
    branches:
      - "*"
  schedule:
    # Daily at 07:13
    - cron: '13 7 * * *'

env:
  QT_DEBUG_PLUGINS: 1

jobs:
  test:
    name: ${{ matrix.task.name }} ${{ matrix.os.name }} ${{ matrix.python.name }} ${{ matrix.reactor.name }}
    runs-on: ${{ matrix.os.runs-on }}
    container: ${{ matrix.os.container[matrix.python.docker] }}
    strategy:
      fail-fast: false
      matrix:
        os:
          - name: Linux
            runs-on: ubuntu-latest
            matrix: linux
            container:
              3.5: docker://python:3.5-buster
              3.6: docker://python:3.6-buster
              3.7: docker://python:3.7-buster
              3.8: docker://python:3.8-buster
              3.9: docker://python:3.9-buster
          - name: Windows
            runs-on: windows-latest
            matrix: windows
          - name: macOS
            runs-on: macos-latest
            matrix: macos
        python:
          - name: CPython 3.5
            tox: py35
            action: 3.5
            docker: 3.5
            matrix: 3.5
            implementation: cpython
            major: 3
          - name: CPython 3.6
            tox: py36
            action: 3.6
            docker: 3.6
            matrix: 3.6
            implementation: cpython
            major: 3
          - name: CPython 3.7
            tox: py37
            action: 3.7
            docker: 3.7
            matrix: 3.7
            implementation: cpython
            major: 3
          - name: CPython 3.8
            tox: py38
            action: 3.8
            docker: 3.8
            matrix: 3.8
            implementation: cpython
            major: 3
          - name: CPython 3.9
            tox: py39
            action: 3.9
            docker: 3.9
            matrix: 3.9
            implementation: cpython
            major: 3
        task:
          - name: Core
            tox: core
          - name: Twisted
            tox: twisted
          - name: asyncio
            tox: asyncio
        exclude:
          - python:
              matrix: 3.9
          - os:
              matrix: windows
    steps:
      - uses: actions/checkout@v2
      - name: Set up ${{ matrix.python.name }}
        if: job.container == ''
        uses: actions/setup-python@v2
        with:
          python-version: '${{ matrix.python.action }}.0-alpha - ${{ matrix.python.action }}.X'
          architecture: x64
      - uses: twisted/python-info-action@v1.0.1
      - name: Install Linux Qt5 dependencies
        if: matrix.os.matrix == 'linux'
        run: |
          apt-get update --yes
          apt-get install --yes libgl1 libgl1-mesa-dev xvfb x11-utils libdbus-1-3 libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0
      - uses: altendky/QTBUG-88688-libxcb-util@v2
        if: matrix.os.matrix == 'linux'
      - name: Install
        run: |
          pip install tox
      - name: Test
        run: |
          tox -v -e "${{ matrix.python.tox }}-${{ matrix.task.tox }}"
      - name: Codecov
        run: |
          tox -v -e codecov
  tasks:
    name: ${{ matrix.task.name }} ${{ matrix.os.name }} ${{ matrix.python.name }}
    runs-on: ${{ matrix.os.runs-on }}
    container: ${{ matrix.os.container[matrix.python.docker] }}
    strategy:
      fail-fast: false
      matrix:
        os:
          - name: Linux
            runs-on: ubuntu-latest
            matrix: linux
            container:
              3.8: docker://python:3.8-buster
        python:
          - name: CPython 3.8
            tox: py38
            action: 3.8
            docker: 3.8
            implementation: cpython
            major: 3
        task:
          - name: Wheel
            tox: wheel
    steps:
      - uses: actions/checkout@v2
      - name: Set up ${{ matrix.python.name }}
        if: job.container == ''
        uses: actions/setup-python@v2
        with:
          python-version: '${{ matrix.python.action }}.0-alpha - ${{ matrix.python.action }}.X'
          architecture: x64
      - uses: twisted/python-info-action@v1.0.1
      - name: Install Linux Qt5 dependencies
        if: matrix.os.matrix == 'linux'
        run: |
          apt-get update --yes
          apt-get install --yes libgl1 libgl1-mesa-dev xvfb x11-utils libdbus-1-3 libxkbcommon-x11-0 libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xinerama0 libxcb-xfixes0
      - uses: altendky/QTBUG-88688-libxcb-util@v2
        if: matrix.os.matrix == 'linux'
      - name: Install
        run: |
          pip install tox
      - name: Test
        run: |
          tox -v -e "${{ matrix.python.tox }}-${{ matrix.task.tox }}"
      - name: Codecov
        run: |
          tox -v -e codecov
      - name: Archive
        uses: actions/upload-artifact@v2
        with:
          name: artifacts
          path: dist
  maybe_publish:
    name: Maybe Publish
    runs-on: ubuntu-latest
    container: docker://python:3.8-buster
    needs:
      - test
      - tasks
    steps:
      - name: Checkout
        uses: actions/checkout@v2
      - name: Download all wheels
        uses: actions/download-artifact@v2
        with:
          name: artifacts
          path: dist
      - name: Install Python packages
        run: |
          python -m venv venv
          venv/bin/python -m pip install --upgrade pip setuptools twine
          venv/bin/python -m pip install --upgrade twine
      - name: Maybe publish
        run: |
          venv/bin/python twineontag.py
        env:
          TWINE_USERNAME: ${{ secrets.TWINE_USERNAME }}
          TWINE_PASSWORD: ${{ secrets.TWINE_PASSWORD }}
  all:
    name: All
    runs-on: ubuntu-latest
    needs:
      - test
      - tasks
      - maybe_publish
    steps:
      - name: This
        shell: python
        run: |
          import this