Docker：dotnet ef 数据库更新失败

Question

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

我的 Program.cs 看起来像这样（默认）：

public class Program
{
    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>();
}

我的 dockerfile 如下所示：

FROM microsoft/dotnet:2.2.0-aspnetcore-runtime AS base
WORKDIR /app
EXPOSE 80

FROM microsoft/dotnet:2.2.103-sdk AS build
WORKDIR /src
COPY ["src/filemanager.csproj", "WebApp/FileManager.WebApp/"]
RUN dotnet restore "WebApp/FileManager.WebApp/filemanager.csproj"
WORKDIR /src/WebApp/FileManager.WebApp
COPY . .
RUN dotnet build "filemanager.csproj" -c Release -o /app
RUN dotnet ef database update

FROM build AS publish
RUN dotnet publish "filemanager.csproj" -c Release -o /app

FROM node:11.6.0-alpine as nodebuild
WORKDIR /src
COPY ["src/client", "ClientApp/"]
WORKDIR /src/ClientApp
RUN yarn
RUN yarn build

FROM base AS final
WORKDIR /app
COPY --from=publish /app .
COPY --from=nodebuild /src/ClientApp/build /app/wwwroot
ENTRYPOINT ["dotnet", "filemanager.dll"]

我究竟做错了什么？如果我删除数据库更新，它会成功部署。

Answer 1

好的，以下是解决我的问题所需执行的步骤：

1. 必须根据此网站重组我的 Program.cs：https://www.ryadel.com/en/buildwebhost-unable-to-create-an-object-of-type-applicationdbcontext-error-idesigntimedbcontextfactory-ef-core- 2-修复/

2. 我必须创建一个 DesignTimeDbContextFactory，它使用 ThefactoryDefaultConnection中找到的字符串创建数据库上下文，如下所示：appsettings.json

public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<FileManagerDbContext>
{
    public FileManagerDbContext CreateDbContext(string[] args)
    {
        IConfigurationRoot configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetCurrentDirectory())
            .AddJsonFile("appsettings.json")
            .Build();
        var builder = new DbContextOptionsBuilder<FileManagerDbContext>();
        var connectionString = configuration.GetConnectionString("DefaultConnection");
        builder.UseSqlite(connectionString);
        return new FileManagerDbContext(builder.Options);
    }
}

3. 在我的 Dockerfile 中，我必须显式复制appsettings.json到 .csproj 文件旁边。就我而言，这意味着将此命令添加到 Dockerfile 中：

COPY ["src/appsettings.json", "WebApp/FileManager.WebApp/"]

经过这些步骤，部署成功。