GitHub Actions

Definition

GitHub Actions est la plateforme CI/CD native de GitHub. Elle permet d'automatiser des workflows de build, test et deploiement directement depuis les repositories GitHub, declenches par des evenements (push, pull request, schedule, webhook).

Lancee en 2019, GitHub Actions est devenue la plateforme CI/CD la plus populaire pour les projets open source et les startups.

Concepts cles

• Workflow : fichier YAML dans .github/workflows/ qui definit l'automatisation
• Event (trigger) : ce qui declenche le workflow (push, PR, cron, manual)
• Job : ensemble de steps qui s'executent sur un runner
• Step : une action ou une commande shell
• Action : module reutilisable (actions/checkout, actions/setup-node)
• Runner : machine qui execute le job (GitHub-hosted ou self-hosted)

Exemple complet

name: CI/CD Pipeline

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

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 22
          cache: 'npm'
      - run: npm ci
      - run: npm run lint
      - run: npm test
      - run: npm run build

  deploy:
    needs: test
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - run: npm ci && npm run build
      - uses: appleboy/scp-action@v0.1.7
        with:
          host: ${{ secrets.SERVER_HOST }}
          username: deploy
          key: ${{ secrets.SSH_KEY }}
          source: "dist/"
          target: "/var/www/monsite"

Fonctionnalites avancees

Matrix builds

strategy:
  matrix:
    node-version: [18, 20, 22]
    os: [ubuntu-latest, windows-latest]

Reusable workflows

jobs:
  call-shared:
    uses: ./.github/workflows/shared-ci.yml
    secrets: inherit

Cache

- uses: actions/cache@v4
  with:
    path: ~/.npm
    key: npm-${{ hashFiles('package-lock.json') }}

Tarification

Les runners self-hosted sont gratuits en minutes.