Actions触发器

1. 触发器概述

GitHub Actions 工作流通过 on 关键字定义触发条件。触发器决定了工作流何时执行，是 CI/CD 流水线的入口。

name: CI
on: push # 最简单的触发器

2. push 触发器

2.1 基本用法

on:
  push:
    branches:
      - main
      - 'release/**' # 通配符匹配 release/1.0, release/2.1
    tags:
      - 'v*' # 匹配 v1.0, v2.0.1
    paths:
      - 'src/**' # 仅 src 目录变更时触发
      - '!src/docs/**' # 排除 src/docs 目录

2.2 过滤模式

2.3 paths 与 paths-ignore 互斥

# 正确：使用 paths
on:
  push:
    branches: [main]
    paths: ['src/**', 'package.json']

# 正确：使用 paths-ignore
on:
  push:
    branches: [main]
    paths-ignore: ['docs/**', '*.md']

# 错误：paths 和 paths-ignore 不能同时使用
on:
  push:
    paths: ['src/**']
    paths-ignore: ['docs/**']  # 语法错误

3. pull_request 触发器

3.1 事件类型

on:
  pull_request:
    types:
      - opened # PR 创建
      - synchronize # PR 有新提交推送
      - reopened # PR 重新打开
      - ready_for_review # PR 从草稿变为可审查
      - labeled # PR 被添加标签
      - closed # PR 关闭（合并或拒绝）

3.2 分支与路径过滤

on:
  pull_request:
    branches:
      - main
      - 'develop/**'
    paths:
      - 'src/**'
      - 'tests/**'
    types: [opened, synchronize]

3.3 pull_request_target

on:
  pull_request_target:
    branches: [main]

与 pull_request 的关键区别：

4. schedule 触发器

4.1 cron 语法

on:
  schedule:
    - cron: '0 2 * * *' # 每天 UTC 2:00
    - cron: '0 2 * * 1-5' # 工作日 UTC 2:00
    - cron: '30 4 1 * *' # 每月1日 UTC 4:30

cron 字段含义：

┌──────── 分钟 (0-59)
│ ┌────── 小时 (0-23)
│ │ ┌──── 日 (1-31)
│ │ │ ┌── 月 (1-12)
│ │ │ │ ┌ 星期 (0-6, 0=周日)
│ │ │ │ │
* * * * *

4.2 常见调度模式

4.3 注意事项

• GitHub 使用 UTC 时区，需换算本地时间
• 最小调度间隔为 5 分钟，更短的间隔会被忽略
• schedule 触发有延迟，不保证精确到秒
• 仓库 60 天无活动后，scheduled workflow 会自动禁用

5. workflow_dispatch 触发器

5.1 手动触发

on:
  workflow_dispatch:
    inputs:
      environment:
        description: '部署环境'
        required: true
        default: 'staging'
        type: choice
        options:
          - development
          - staging
          - production
      version:
        description: '部署版本'
        required: true
        type: string
      dry-run:
        description: '试运行模式'
        required: false
        type: boolean
        default: false

5.2 输入类型

5.3 在工作流中使用输入

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - name: Deploy
        run: |
          echo "Deploying to ${{ github.event.inputs.environment }}"
          echo "Version: ${{ github.event.inputs.version }}"
          echo "Dry run: ${{ github.event.inputs.dry-run }}"

6. 其他触发器

6.1 repository_dispatch

on:
  repository_dispatch:
    types: [deploy, rollback]

通过 API 触发：

curl -X POST \
  -H "Authorization: token $GITHUB_TOKEN" \
  -H "Accept: application/vnd.github.v3+json" \
  https://api.github.com/repos/owner/repo/dispatches \
  -d '{"event_type": "deploy", "client_payload": {"env": "production"}}'

6.2 issue_comment

on:
  issue_comment:
    types: [created]

可用于实现斜杠命令：

jobs:
  command:
    if: github.event.issue.pull_request && startsWith(github.event.comment.body, '/deploy')
    runs-on: ubuntu-latest
    steps:
      - run: echo "Deploy triggered by comment"

6.3 release

on:
  release:
    types: [published, created, edited]

6.4 多触发器组合

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
  schedule:
    - cron: '0 2 * * *'
  workflow_dispatch:

7. 触发条件优化

7.1 避免冗余触发

# 问题：PR 中的 push 也会触发 push 事件
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

# 解决：使用条件判断跳过重复
jobs:
  build:
    if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork == false

7.2 跳过 CI

# 提交信息中包含 [skip ci] 或 [ci skip] 可跳过触发
git commit -m "docs: update README [skip ci]"

7.3 触发器与权限

permissions:
  contents: read
  issues: write
  pull-requests: write

jobs:
  comment:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/github-script@v7
        with:
          script: |
            github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: 'CI passed!'
            })