GitHub Actions 实战

基础概念

GitHub Actions 是 GitHub 提供的 CI/CD 平台，通过 Workflow 文件定义自动化流程。

核心组件

组件	说明
Workflow	一个完整的自动化流程，由 YAML 文件定义
Job	Workflow 中的一组步骤，运行在同一 Runner 上
Step	Job 中的单个任务，可以运行命令或 Action
Action	可复用的自动化单元，类似函数
Runner	执行 Workflow 的服务器

基本 Workflow 结构

name: CI Pipeline

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

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v4

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

    - name: Install dependencies
      run: npm ci

    - name: Run tests
      run: npm test

    - name: Build
      run: npm run build

高级用法

矩阵构建

在多个操作系统和版本组合中并行测试：

jobs:
  test:
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest, macos-latest]
        node: [18, 20, 22]

    runs-on: ${{ matrix.os }}

    steps:
    - uses: actions/checkout@v4
    - uses: actions/setup-node@v4
      with:
        node-version: ${{ matrix.node }}
    - run: npm ci && npm test

工作流依赖与产物传递

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
    - run: npm ci && npm run build
    - uses: actions/upload-artifact@v4
      with:
        name: build-output
        path: dist/

  deploy:
    needs: build
    runs-on: ubuntu-latest
    steps:
    - uses: actions/download-artifact@v4
      with:
        name: build-output
    - run: ./deploy.sh

条件执行

jobs:
  deploy:
    if: github.ref == 'refs/heads/main' && github.event_name == 'push'
    steps:
    - run: echo "Deploying to production"

  notify:
    if: failure()
    steps:
    - run: echo "Pipeline failed!"

环境与密钥管理

jobs:
  deploy:
    environment: production
    steps:
    - name: Deploy to production
      run: ./deploy.sh
      env:
        API_TOKEN: ${{ secrets.PRODUCTION_API_TOKEN }}
        DEPLOY_KEY: ${{ secrets.DEPLOY_SSH_KEY }}

常用 Actions

# 代码检出
- uses: actions/checkout@v4

# Docker 登录
- uses: docker/login-action@v3
  with:
    registry: ghcr.io
    username: ${{ github.actor }}
    password: ${{ secrets.GITHUB_TOKEN }}

# 构建和推送 Docker 镜像
- uses: docker/build-push-action@v5
  with:
    push: true
    tags: ghcr.io/myorg/myapp:${{ github.sha }}

# 缓存依赖
- uses: actions/cache@v4
  with:
    path: ~/.npm
    key: ${{ runner.os }}-node-${{ hashFiles('**/package-lock.json') }}

定时任务 Workflow

name: Nightly Cleanup

on:
  schedule:
    - cron: '0 6 * * *'  # 每天早上 6 点

jobs:
  cleanup:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v4
    - name: Clean stale branches
      run: ./scripts/cleanup-stale-branches.sh
      env:
        GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

最佳实践

1. 使用 Action 版本锁

# 推荐：锁定到具体版本
- uses: actions/checkout@v4

# 不推荐：使用 @main 或 @master
- uses: actions/checkout@main

2. 优化缓存

- uses: actions/setup-node@v4
  with:
    node-version: 20
    cache: npm        # 自动缓存 node_modules

3. 细粒度触发条件

on:
  push:
    paths:
    - 'src/**'
    - 'tests/**'
    - 'package.json'
  pull_request:
    paths-ignore:
    - 'docs/**'
    - 'README.md'

4. 并行化与超时

jobs:
  test:
    timeout-minutes: 30
    strategy:
      fail-fast: false  # 一个失败不影响其他矩阵任务
      matrix:
        shard: [1, 2, 3, 4]

总结

GitHub Actions 提供了强大而灵活的 CI/CD 能力，通过 YAML 配置即可实现从简单测试到复杂的多环境部署流水线。善用矩阵构建、缓存和条件执行等功能，可以显著提升开发和交付效率。