无法通过GitHub Actions将Flutter应用发布至Azure App Service

我按照教程将Flutter应用部署至Azure App Service，部署中心自动生成了以下GitHub Actions工作流：

name: Build and deploy Node.js app to Azure Web App - flutter-test

on:
  push:
    branches:
      - master
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v2

      - name: Set up Node.js version
        uses: actions/setup-node@v1
        with:
          node-version: '18.x'

      - name: npm install, build, and test
        run: |
          npm install
          npm run build --if-present
          npm run test --if-present
      - name: Upload artifact for deployment job
        uses: actions/upload-artifact@v2
        with:
          name: node-app
          path: .

  deploy:
    runs-on: ubuntu-latest
    needs: build
    environment:
      name: 'Production'
      url: ${{ steps.deploy-to-webapp.outputs.webapp-url }}

    steps:
      - name: Download artifact from build job
        uses: actions/download-artifact@v2
        with:
          name: node-app

      - name: 'Deploy to Azure Web App'
        id: deploy-to-webapp
        uses: azure/webapps-deploy@v2
        with:
          app-name: 'flutter-test'
          slot-name: 'Production'
          publish-profile: ${{ secrets.AZUREAPPSERVICE_PUBLISHPROFILE_9F371C7309EE423496F3C77A4D2B4CAA }}
          package: .

工作流执行成功，但访问App Service URL时显示默认Node.js欢迎页（如下所示），而非预期的默认Flutter启动项目：

出现该问题的核心原因是：自动生成的Node.js工作流未执行Flutter Web构建步骤，直接部署了项目根目录文件，导致Azure App Service加载默认Node.js页面而非Flutter产物。

1. 重构Build作业流程 #

替换原Node.js构建步骤，改为Flutter Web专属构建流程，生成正确的Web产物：

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3

      # 配置稳定版Flutter环境
      - name: Set up Flutter
        uses: subosito/flutter-action@v2
        with:
          flutter-version: 'stable'

      # 安装Flutter项目依赖
      - name: Install Flutter dependencies
        run: flutter pub get

      # 构建生产环境Flutter Web产物，输出至build/web目录
      - name: Build Flutter Web
        run: flutter build web --release

      # 仅上传构建好的Web产物，减少冗余
      - name: Upload build artifact
        uses: actions/upload-artifact@v3
        with:
          name: flutter-web-build
          path: build/web

2. 调整Deploy作业的部署路径 #

修改部署阶段，确保将Flutter Web产物部署到Azure App Service：

deploy:
    runs-on: ubuntu-latest
    needs: build
    environment:
      name: 'Production'
      url: ${{ steps.deploy-to-webapp.outputs.webapp-url }}

    steps:
      - name: Download Flutter build artifact
        uses: actions/download-artifact@v3
        with:
          name: flutter-web-build

      - name: Deploy to Azure Web App
        id: deploy-to-webapp
        uses: azure/webapps-deploy@v2
        with:
          app-name: 'flutter-test'
          slot-name: 'Production'
          publish-profile: ${{ secrets.AZUREAPPSERVICE_PUBLISHPROFILE_9F371C7309EE423496F3C77A4D2B4CAA }}
          package: .

3. 配置SPA路由支持（可选） #

若部署后Flutter路由功能异常，可在Azure门户的App Service 配置 > 常规设置中，设置启动命令为：

pm2 serve /home/site/wwwroot --no-daemon --spa

该命令启用SPA模式，确保所有路由请求指向index.html，适配Flutter Web单页应用特性。

完成修改后，重新推送代码触发GitHub Actions工作流，部署成功后即可访问默认Flutter启动项目。

内容的提问来源于stack exchange，提问作者Code Ratchet