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GitHub Actions

核心概念​

概念说明
Workflow一条自动化流水线，存放在 .github/workflows/
Event触发 Workflow 的事件（push、pull_request、schedule 等）
JobWorkflow 中的一个任务，默认并行执行
StepJob 中的一个步骤（运行命令或使用 Action）
Action可复用的步骤（Marketplace 中有大量社区 Action）
Runner执行 Job 的服务器（GitHub-hosted 或 self-hosted）

完整示例​

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

# 触发条件
on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]
  # 定时触发
  schedule:
    - cron: '0 2 * * 1'  # 每周一凌晨 2 点

# 环境变量
env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  # ===== 代码检查 =====
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: 20
          cache: 'pnpm'

      - run: pnpm install --frozen-lockfile
      - run: pnpm lint
      - run: pnpm type-check

  # ===== 测试 =====
  test:
    runs-on: ubuntu-latest
    needs: lint
    strategy:
      # 矩阵构建：多版本并行测试
      matrix:
        node-version: [18, 20, 22]
    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-node@v4
        with:
          node-version: ${{ matrix.node-version }}
          cache: 'pnpm'

      - run: pnpm install --frozen-lockfile
      - run: pnpm test -- --coverage

      # 上传测试覆盖率
      - uses: codecov/codecov-action@v4
        if: matrix.node-version == 20

  # ===== 构建并推送镜像 =====
  build:
    runs-on: ubuntu-latest
    needs: test
    # 仅 main 分支触发
    if: github.ref == 'refs/heads/main'
    permissions:
      contents: read
      packages: write
    outputs:
      image-tag: ${{ steps.meta.outputs.tags }}
    steps:
      - uses: actions/checkout@v4

      # Docker Buildx
      - uses: docker/setup-buildx-action@v3

      # 登录 GitHub Container Registry
      - uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      # 生成镜像标签
      - id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=sha,prefix=
            type=raw,value=latest

      # 构建并推送
      - uses: docker/build-push-action@v5
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

  # ===== 部署 =====
  deploy:
    runs-on: ubuntu-latest
    needs: build
    environment: production   # 需要审批
    steps:
      - uses: actions/checkout@v4

      # 部署到 K8s
      - uses: azure/k8s-set-context@v4
        with:
          kubeconfig: ${{ secrets.KUBE_CONFIG }}

      - run: |
          kubectl set image deployment/myapp \
            myapp=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ github.sha }} \
            -n production
          kubectl rollout status deployment/myapp -n production --timeout=300s

常用技巧​

缓存依赖​

- uses: actions/cache@v4
  with:
    path: |
      ~/.pnpm-store
      node_modules
    key: ${{ runner.os }}-pnpm-${{ hashFiles('pnpm-lock.yaml') }}
    restore-keys: |
      ${{ runner.os }}-pnpm-

条件执行​

steps:
  # 仅 PR 时运行
  - if: github.event_name == 'pull_request'
    run: echo "This is a PR"

  # 仅文件变更时运行
  - uses: dorny/paths-filter@v3
    id: changes
    with:
      filters: |
        backend:
          - 'src/server/**'
        frontend:
          - 'src/client/**'

  - if: steps.changes.outputs.backend == 'true'
    run: pnpm test:backend

Secrets 管理​

# 在 Settings → Secrets and variables → Actions 中配置
steps:
  - run: |
      echo "Deploying to ${{ vars.DEPLOY_ENV }}"
    env:
      API_KEY: ${{ secrets.API_KEY }}       # 密钥
      DB_URL: ${{ secrets.DATABASE_URL }}

可复用 Workflow​

.github/workflows/reusable-deploy.yml
on:
  workflow_call:
    inputs:
      environment:
        required: true
        type: string
    secrets:
      KUBE_CONFIG:
        required: true

jobs:
  deploy:
    runs-on: ubuntu-latest
    environment: ${{ inputs.environment }}
    steps:
      - run: echo "Deploying to ${{ inputs.environment }}"
调用方
jobs:
  deploy-staging:
    uses: ./.github/workflows/reusable-deploy.yml
    with:
      environment: staging
    secrets:
      KUBE_CONFIG: ${{ secrets.KUBE_CONFIG_STAGING }}

常见面试问题​

Q1: GitHub Actions 的触发方式有哪些？​

答案：

  • push / pull_request：代码事件（可过滤分支和路径）
  • schedule：定时触发（cron 语法）
  • workflow_dispatch：手动触发（可带参数）
  • workflow_call：被其他 Workflow 调用
  • release：发布事件
  • repository_dispatch：外部 API 触发

Q2: 如何优化 CI 构建速度？​

答案：

  1. 缓存依赖：actions/cache 缓存 node_modules / Maven 仓库
  2. 并行 Job：独立的 lint / test / build 并行运行
  3. 路径过滤：paths-filter 只运行受影响的测试
  4. Docker 层缓存：使用 cache-from: type=gha
  5. Self-hosted Runner：自建 Runner 避免队列等待
  6. 矩阵构建：利用多 Runner 并行测试不同版本

相关链接​