我有一个以dotnet run命令开头的 dotnet 应用程序。我还有一个 React 应用程序，我从yarn start.
当我打开浏览器localhost:3000（反应应用程序所在的位置）时，服务器日志如下所示：
....this goes on for long
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/build/bundle.js …我刚刚开始在我的项目中使用 EF，docker ef database update当我从项目文件夹本地运行该命令时，该命令运行完美。
但是，当我尝试使用 docker 部署应用程序时，它失败了：
RUN dotnet ef database update
我收到以下错误消息：
An error occurred while accessing the IWebHost on class 'Program'. Continuing without the application service provider. Error: The configuration file 'appsettings.json' was not found and is not optional. The physical path is '/src/WebApp/FileManager.WebApp/bin/Debug/netcoreapp2.2/appsettings.json'.
Unable to create an object of type 'FileManagerDbContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728
The command '/bin/sh -c dotnet ef database update' returned a non-zero code: 1 …