Unit tests workflow (awslabs/aws-cfn-template-flip)

The Unit tests workflow from awslabs/aws-cfn-template-flip, explained and optimized by Latchkey.

What it does

This is the Unit tests workflow from the awslabs/aws-cfn-template-flip repository, a real project running GitHub Actions. It is shown here with attribution under its Apache-2.0 license.

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

The workflow

on:
  push:
    branches: [ master ]

name: Unit tests

jobs:
  test:
    name: Test
    runs-on: ubuntu-latest
    strategy:
      matrix:
        python-version: [3.6, 3.7, 3.8, 3.9, "3.10"]
    steps:
      - name: Checkout code
        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 -U pip
          pip install -r requirements.txt
          pip install tox-gh-actions

      - name: Run tests
        run: tox

      - name: Upload coverage reports to Codecov
        uses: codecov/codecov-action@v2

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.

on:
  push:
    branches: [ master ]
 
name: Unit tests
 
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true
 
jobs:
  test:
    timeout-minutes: 30
    name: Test
    runs-on: latchkey-small
    strategy:
      matrix:
        python-version: [3.6, 3.7, 3.8, 3.9, "3.10"]
    steps:
      - name: Checkout code
        uses: actions/checkout@v2
 
      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v2
        with:
          cache: 'pip'
          python-version: ${{ matrix.python-version }}
 
      - name: Install dependencies
        run: |
          python -m pip install -U pip
          pip install -r requirements.txt
          pip install tox-gh-actions
 
      - name: Run tests
        run: tox
 
      - name: Upload coverage reports to Codecov
        uses: codecov/codecov-action@v2
 

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• Cancel superseded runs when a branch or PR gets a newer push.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 1 job (5 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