Build workflow (saintslab/carbontracker)

The Build workflow from saintslab/carbontracker, explained and optimized by Latchkey.

CI health: F - at risk

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Source: saintslab/carbontracker.github/workflows/publish.ymlLicense MITView source

What it does

This is the Build workflow from the saintslab/carbontracker repository, a real project running GitHub Actions. It is shown here with attribution under its MIT license.

Below, Latchkey shows a faster, safer version produced by its optimization engine.

The workflow

workflow (.yml)

name: Build

on:
  push:
    tags:
      - 'v*.*.*'
      - 'dev-v*.*.*'

jobs:
  test:
    runs-on: ubuntu-22.04
    strategy:
      matrix:
        python-version: [3.7, 3.8, 3.9, '3.10', '3.11', '3.12']

    steps:
    - uses: actions/checkout@v4
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v3
      with:
        python-version: ${{ matrix.python-version }}

    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install .\[test,docs\]

    - name: Run tests
      run: python -m unittest discover

  lint:
    needs: test
    runs-on: ubuntu-22.04
    strategy:
      matrix:
        python-version: [3.7, 3.8, 3.9, '3.10']

    steps:
    - uses: actions/checkout@v4
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v4
      with:
        python-version: ${{ matrix.python-version }}

    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install .\[test,docs\]
        pip install flake8 black

    - name: Lint with flake8
      run: flake8 carbontracker --count --select=E9,F63,F7,F82 --show-source --statistics

    - name: Format with Black
      run: black --line-length 120 carbontracker

  build-n-publish:
    needs: [test, lint]
    runs-on: ubuntu-22.04
    steps:
      - uses: actions/checkout@v4
      - name: Set up Python 3.10
        uses: actions/setup-python@v4
        with:
          python-version: "3.10"

      - name: Install build dependencies
        run: |
          python -m pip install --upgrade pip
          pip install build

      - name: Build the package
        run: python -m build

      - name: Publish to Test PyPI
        if: startsWith(github.ref, 'refs/tags/dev-v')
        uses: pypa/gh-action-pypi-publish@v1.12.4
        with:
          user: __token__
          password: ${{ secrets.TEST_PYPI_API_TOKEN }}
          repository_url: https://test.pypi.org/legacy/

      - name: Publish to PyPI
        if: startsWith(github.ref, 'refs/tags/v')
        uses: pypa/gh-action-pypi-publish@v1.12.4
        with:
          user: __token__
          password: ${{ secrets.PYPI_API_TOKEN }}

The same workflow, on Latchkey

Estimated ~20% faster on cache hits, plus fewer wasted runs and a safer supply chain. Added and changed lines are highlighted.

name: Build
 
on:
  push:
    tags:
      - 'v*.*.*'
      - 'dev-v*.*.*'
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  test:
    timeout-minutes: 30
    runs-on: latchkey-small
    strategy:
      matrix:
        python-version: [3.7, 3.8, 3.9, '3.10', '3.11', '3.12']
 
    steps:
    - uses: actions/checkout@v4
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v3
      with:
        cache: 'pip'
        python-version: ${{ matrix.python-version }}
 
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install .\[test,docs\]
 
    - name: Run tests
      run: python -m unittest discover
 
  lint:
    timeout-minutes: 30
    needs: test
    runs-on: latchkey-small
    strategy:
      matrix:
        python-version: [3.7, 3.8, 3.9, '3.10']
 
    steps:
    - uses: actions/checkout@v4
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v4
      with:
        cache: 'pip'
        python-version: ${{ matrix.python-version }}
 
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install .\[test,docs\]
        pip install flake8 black
 
    - name: Lint with flake8
      run: flake8 carbontracker --count --select=E9,F63,F7,F82 --show-source --statistics
 
    - name: Format with Black
      run: black --line-length 120 carbontracker
 
  build-n-publish:
    timeout-minutes: 30
    needs: [test, lint]
    runs-on: latchkey-small
    steps:
      - uses: actions/checkout@v4
      - name: Set up Python 3.10
        uses: actions/setup-python@v4
        with:
          cache: 'pip'
          python-version: "3.10"
 
      - name: Install build dependencies
        run: |
          python -m pip install --upgrade pip
          pip install build
 
      - name: Build the package
        run: python -m build
 
      - name: Publish to Test PyPI
        if: startsWith(github.ref, 'refs/tags/dev-v')
        uses: pypa/gh-action-pypi-publish@v1.12.4
        with:
          user: __token__
          password: ${{ secrets.TEST_PYPI_API_TOKEN }}
          repository_url: https://test.pypi.org/legacy/
 
      - name: Publish to PyPI
        if: startsWith(github.ref, 'refs/tags/v')
        uses: pypa/gh-action-pypi-publish@v1.12.4
        with:
          user: __token__
          password: ${{ secrets.PYPI_API_TOKEN }}

What changed

Run on Latchkey managed runners with one line (runs-on), which apply the fixes below automatically and self-heal transient failures. This example uses latchkey-small; pick the runner size that fits the job.
Cancel superseded runs when a branch or PR gets a newer push.
Cache dependency installs on the setup step so they are served from cache.
Add a job timeout so a hung step cannot burn hours of runner time.

1 third-party action is referenced by a movable tag. Pin it to the commit SHA (Latchkey resolves and applies this automatically) so a repointed tag cannot change what runs.

What Latchkey heals here

This workflow has steps that commonly fail on transient issues (network, registries, flaky browsers). On Latchkey managed runners they are detected, retried, and self-healed instead of failing your build:

Dependency installs

This workflow runs 3 jobs (11 with the matrix expanded) per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow

actions/checkout actions/setup-python