teachingai/github-actions

When to use this skill

Use this skill whenever the user wants to:

• Create or debug GitHub Actions workflows (.github/workflows/*.yml)
• Configure triggers, jobs, steps, secrets, matrix strategies, or reusable workflows
• Integrate checkout, build, test, deploy, and notification steps
• Optimize workflow performance with caching and concurrency controls

How to use this skill

Workflow

1. Create workflow file — add YAML to .github/workflows/
2. Define triggers — specify on events (push, pull_request, schedule, etc.)
3. Configure jobs and steps — use official and third-party actions
4. Test and iterate — push to trigger, check logs, fix failures

Quick Start Example

# .github/workflows/ci.yml
name: CI Pipeline

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  test:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [18, 20]
    steps:
      - uses: actions/checkout@v4

      - name: Setup Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}
          cache: 'npm'

      - run: npm ci
      - run: npm test

  deploy:
    needs: test
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci && npm run build
      - name: Deploy
        env:
          DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN }}
        run: ./scripts/deploy.sh

Reusable Workflow Example

# .github/workflows/reusable-build.yml
on:
  workflow_call:
    inputs:
      node-version:
        type: string
        default: '20'

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ inputs.node-version }}
      - run: npm ci && npm run build

Best Practices

• Store tokens and keys in secrets — never echo sensitive values in logs
• Add id and outputs to key steps for downstream consumption
• Cache dependencies with actions/cache or built-in setup action caching
• Use concurrency to cancel outdated workflow runs on the same branch
• Pin action versions to a SHA or major version tag for security

Troubleshooting

• Workflow not triggered: Verify the on event matches your branch and event type
• Permission denied: Check permissions block and repository settings for GITHUB_TOKEN scope
• Cache miss: Ensure the cache key includes lockfile hash (e.g., hashFiles('**/package-lock.json'))
• Matrix failures: Use continue-on-error selectively; check logs per matrix combination

Keywords

github actions, workflow, yaml, CI/CD, automation, matrix strategy, reusable workflows, secrets