GitHub Actions

Create and troubleshoot GitHub Actions workflows for CI/CD pipelines.

Instructions

When writing:

1. Understand the pipeline requirements
2. Check existing workflows in .github/workflows/
3. Write workflow following best practices below
4. Validate with actionlint if available

When debugging:

1. Read the workflow file
2. Check recent runs: gh run list
3. View run logs: gh run view <run-id> --log-failed
4. Identify and fix issues

Workflow structure

name: CI

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

permissions:
  contents: read

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: "20"
          cache: "npm"

      - name: Install dependencies
        run: npm ci

      - name: Run tests
        run: npm test

Best practices

• MUST pin actions to full SHA: uses: actions/checkout@abc123...
• MUST set minimal permissions: (not defaults)
• MUST use npm ci not npm install for reproducibility
• Use caching for dependencies
• Use matrix builds for multiple versions
• Use job dependencies with needs:
• Use concurrency to cancel outdated runs
• Store secrets in GitHub Secrets, reference with ${{ secrets.NAME }}

Security

permissions:
  contents: read # Minimal permissions

env:
  API_KEY: ${{ secrets.API_KEY }} # Never hardcode

Common patterns

# Caching
- uses: actions/cache@v4
  with:
    path: ~/.cache/pip
    key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}

# Matrix
strategy:
  matrix:
    node: [18, 20, 22]
    os: [ubuntu-latest, macos-latest]

# Concurrency
concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true

# Conditional
if: github.event_name == 'push' && github.ref == 'refs/heads/main'

Debug commands

gh run list --limit 10
gh run view <run-id>
gh run view <run-id> --log-failed
gh run rerun <run-id>

Rules

• MUST use pinned action versions (SHA or version tag)
• MUST set explicit permissions
• Never hardcode secrets in workflow files
• Never use pull_request_target with checkout of PR code
• Always test workflows in a branch first