Linter workflow (asteroid-team/asteroid)

The Linter workflow from asteroid-team/asteroid, explained and optimized by Latchkey.

What it does

This is the Linter workflow from the asteroid-team/asteroid 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

name: Linter
on: [push, pull_request]

jobs:
  code-black:
    name: CI
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v5
      - name: Set up Python 3.13
        uses: actions/setup-python@v6
        with:
          python-version: 3.13

      - name: Install Black and flake8
        run: pip install black==25.9.0 flake8
      - name: Run Black
        run: python -m black --config=pyproject.toml --check asteroid tests egs

      - name: Link with flake8
        # Exit on important linting errors and warn about others.
        run: |
          python -m flake8  asteroid tests  --show-source --statistics  --select=F6,F7,F82,F52
          python -m flake8 --config .flake8 --exit-zero asteroid tests  --statistics

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: Linter
on: [push, pull_request]
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  code-black:
    timeout-minutes: 30
    name: CI
    runs-on: latchkey-small
    steps:
      - name: Checkout
        uses: actions/checkout@v5
      - name: Set up Python 3.13
        uses: actions/setup-python@v6
        with:
          cache: 'pip'
          python-version: 3.13
 
      - name: Install Black and flake8
        run: pip install black==25.9.0 flake8
      - name: Run Black
        run: python -m black --config=pyproject.toml --check asteroid tests egs
 
      - name: Link with flake8
        # Exit on important linting errors and warn about others.
        run: |
          python -m flake8  asteroid tests  --show-source --statistics  --select=F6,F7,F82,F52
          python -m flake8 --config .flake8 --exit-zero asteroid tests  --statistics
 

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• Cancel superseded runs when a branch or PR gets a newer push.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.

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 1 job per trigger. On Latchkey the same minutes cost up to 58% less than GitHub-hosted, with zero queue time.

Actions used in this workflow