从Docker容器进行dotnet还原失败

Question

过去几天，我对此进行了研究，但发现的任何研究都没有帮助我解决此问题，包括重启Docker，重启Docker服务，重启Visual Studio，删除Nuget，调整代理设置，调整Nuget。配置等。

最终，我收到的错误消息是Unable to load the service index for source https://api.nuget.org/v3/index.json.，但是请您忍受，我正在给出具体步骤来重现此错误。

当我在Visual Studio 2019中创建ASP.NET Core Web应用程序时，然后将Docker支持添加到项目中（右键单击项目，选择添加-> Docker支持...），将创建一个如下所示的Dockerfile：

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-nanoserver-1809 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/core/sdk:3.1-nanoserver-1809 AS build
WORKDIR /src
COPY ["WebApplication3/WebApplication3.csproj", "WebApplication3/"]
RUN dotnet restore "WebApplication3/WebApplication3.csproj"
COPY . .
WORKDIR "/src/WebApplication3"
RUN dotnet build "WebApplication3.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "WebApplication3.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "WebApplication3.dll"]

当我构建docker映像时（右键单击dockerfile，选择Build Docker Image），它可以正常运行，并且我得到：

Starting up container(s)...
docker build -f "C:\Users\TheUser\source\repos\WebApplication3\WebApplication3\Dockerfile" --force-rm -t webapplication3:dev --target base  --label "com.microsoft.created-by=visual-studio" --label "com.microsoft.visual-studio.project-name=WebApplication3" "C:\Users\TheUser\source\repos\WebApplication3" 
Sending build context to Docker daemon  4.396MB

Step 1/6 : FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-nanoserver-1809 AS base
 ---> dc28376d4369
Step 2/6 : WORKDIR /app
 ---> Using cache
 ---> d0cbefb504d1
Step 3/6 : EXPOSE 80
 ---> Using cache
 ---> 865f960359d6
Step 4/6 : EXPOSE 443
 ---> Using cache
 ---> 4d040d5c8a4c
Step 5/6 : LABEL com.microsoft.created-by=visual-studio
 ---> Using cache
 ---> 4223be37abec
Step 6/6 : LABEL com.microsoft.visual-studio.project-name=WebApplication3
 ---> Running in d1ced38ba0fa
Removing intermediate container d1ced38ba0fa
 ---> fb400230edf4
Successfully built fb400230edf4
Successfully tagged webapplication3:dev
docker run -dt -v "C:\Users\TheUser\onecoremsvsmon\16.4.0067.0:C:\remote_debugger:ro" -v "C:\Users\TheUser\source\repos\WebApplication3\WebApplication3:C:\app" -v "C:\Users\TheUser\source\repos\WebApplication3:C:\src" -v "C:\Users\TheUser\AppData\Roaming\Microsoft\UserSecrets:C:\Users\ContainerUser\AppData\Roaming\Microsoft\UserSecrets:ro" -v "C:\Users\TheUser\AppData\Roaming\ASP.NET\Https:C:\Users\ContainerUser\AppData\Roaming\ASP.NET\Https:ro" -v "C:\Users\TheUser\.nuget\packages\:c:\.nuget\fallbackpackages2" -v "C:\Program Files\dotnet\sdk\NuGetFallbackFolder:c:\.nuget\fallbackpackages" -e "DOTNET_USE_POLLING_FILE_WATCHER=1" -e "ASPNETCORE_ENVIRONMENT=Development" -e "ASPNETCORE_URLS=https://+:443;http://+:80" -e "NUGET_PACKAGES=c:\.nuget\fallbackpackages2" -e "NUGET_FALLBACK_PACKAGES=c:\.nuget\fallbackpackages;c:\.nuget\fallbackpackages2" -P --name WebApplication3 --entrypoint C:\remote_debugger\x64\msvsmon.exe webapplication3:dev /noauth /anyuser /silent /nostatus /noclrwarn /nosecuritywarn /nofirewallwarn /nowowwarn /fallbackloadremotemanagedpdbs /timeout:2147483646 /LogDebuggeeOutputToStdOut 
eba5dec02ed7a80158340d6f8d6af504b86edf7cd6944eb1d4ce71f7847fabb5
Container started successfully.
========== Finished ==========

但是，如果我向解决方案中添加.Net核心类库，则将该类库添加为对Web应用程序的项目引用，然后再次添加Docker支持，则会得到一个新的Dockerfile，如下所示：

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-nanoserver-1809 AS base
WORKDIR /app
EXPOSE 80
EXPOSE 443

FROM mcr.microsoft.com/dotnet/core/sdk:3.1-nanoserver-1809 AS build
WORKDIR /src
COPY ["WebApplication3/WebApplication3.csproj", "WebApplication3/"]
COPY ["ClassLibrary1/ClassLibrary1.csproj", "ClassLibrary1/"]
RUN dotnet restore "WebApplication3/WebApplication3.csproj"
COPY . .
WORKDIR "/src/WebApplication3"
RUN dotnet build "WebApplication3.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "WebApplication3.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "WebApplication3.dll"]

当我这次再次构建Docker Image时，出现如下错误：

1>------ Rebuild All started: Project: ClassLibrary1, Configuration: Debug Any CPU ------
1>ClassLibrary1 -> C:\Users\TheUser\source\repos\WebApplication3\ClassLibrary1\bin\Debug\netcoreapp3.1\ClassLibrary1.dll
2>------ Rebuild All started: Project: WebApplication3, Configuration: Debug Any CPU ------
2>docker rm -f eba5dec02ed7a80158340d6f8d6af504b86edf7cd6944eb1d4ce71f7847fabb5
2>eba5dec02ed7a80158340d6f8d6af504b86edf7cd6944eb1d4ce71f7847fabb5
2>WebApplication3 -> C:\Users\TheUser\source\repos\WebApplication3\WebApplication3\bin\Debug\netcoreapp3.1\WebApplication3.dll
2>WebApplication3 -> C:\Users\TheUser\source\repos\WebApplication3\WebApplication3\bin\Debug\netcoreapp3.1\WebApplication3.Views.dll
2>Docker version 19.03.8, build afacb8b
2>docker build -f "c:\users\TheUser\source\repos\webapplication3\webapplication3\dockerfile" --force-rm -t webapplication3  --label "com.microsoft.created-by=visual-studio" --label "com.microsoft.visual-studio.project-name=WebApplication3" "c:\users\TheUser\source\repos\webapplication3"
2>Sending build context to Docker daemon    4.4MB
2>
2>Step 1/20 : FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-nanoserver-1809 AS base
2> ---> dc28376d4369
2>Step 2/20 : WORKDIR /app
2> ---> Using cache
2> ---> d0cbefb504d1
2>Step 3/20 : EXPOSE 80
2> ---> Using cache
2>Step 4/20 : EXPOSE 443
2> ---> 865f960359d6
2> ---> Using cache
2> ---> 4d040d5c8a4c
2>Step 5/20 : FROM mcr.microsoft.com/dotnet/core/sdk:3.1-nanoserver-1809 AS build
2> ---> c67fa4d2a089
2>Step 6/20 : WORKDIR /src
2> ---> Using cache
2> ---> 14763e98238e
2>Step 7/20 : COPY ["WebApplication3/WebApplication3.csproj", "WebApplication3/"]
2> ---> ad0ded95d169
2>Step 8/20 : COPY ["ClassLibrary1/ClassLibrary1.csproj", "ClassLibrary1/"]
2> ---> 22667eda405c
2>Step 9/20 : RUN dotnet restore "WebApplication3/WebApplication3.csproj"
2> ---> Running in a3e6a184b4e9
2>  Restore completed in 495.4 ms for C:\src\ClassLibrary1\ClassLibrary1.csproj.
2>C:\Program Files\dotnet\sdk\3.1.201\NuGet.targets(124,5): error : Unable to load the service index for source https://api.nuget.org/v3/index.json. [C:\src\WebApplication3\WebApplication3.csproj]
2>C:\Program Files\dotnet\sdk\3.1.201\NuGet.targets(124,5): error :   No such host is known. [C:\src\WebApplication3\WebApplication3.csproj]
2>Removing intermediate container a3e6a184b4e9
2>The command 'cmd /S /C dotnet restore "WebApplication3/WebApplication3.csproj"' returned a non-zero code: 1
2>c:\users\TheUser\source\repos\webapplication3\webapplication3\dockerfile : error CTC1014: Docker command failed with exit code 1.
2>c:\users\TheUser\source\repos\webapplication3\webapplication3\dockerfile : error CTC1014: The command 'cmd /S /C dotnet restore "WebApplication3/WebApplication3.csproj"' returned a non-zero code: 1
2>Done building project "WebApplication3.csproj" -- FAILED.
========== Rebuild All: 1 succeeded, 1 failed, 0 skipped ==========

应该很容易复制。为什么在没有类库引用的情况下可以正常工作，然后在添加引用时出错？我是否需要额外更新一些Dockerfile？我一直在兜圈子，与此主题相关的其他帖子都没有用这种方式表述或给我任何对我有用的答案。

Answer 1

实际错误似乎是：

Unable to load the service index for source https://api.nuget.org/v3/index.json

这意味着nuget在尝试下载依赖项时无法访问端点。

此处列出了许多解决方案

https://github.com/NuGet/Home/issues/2880

还有

Nuget connection attempt failed "Unable to load the service index for source"

Answer 2

无法复制它。这是我的docker文件。

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1-buster-slim AS base
WORKDIR /app
EXPOSE 80

FROM mcr.microsoft.com/dotnet/core/sdk:3.1-buster AS build
WORKDIR /src
COPY ["WebApplication1.csproj", ""]
COPY ["../ClassLibrary1/ClassLibrary1.csproj", "../ClassLibrary1/"]
RUN dotnet restore "./WebApplication1.csproj"
COPY . .
WORKDIR "/src/."
RUN dotnet build "WebApplication1.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "WebApplication1.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "WebApplication1.dll"]

不同的行：

COPY ["../ClassLibrary1/ClassLibrary1.csproj", "../ClassLibrary1/"]
RUN dotnet restore "./WebApplication1.csproj"

我认为您的csproj和sln文件位于不同的文件夹中。使用Visual Studio时，请确保选择以下选项：将解决方案和项目文件放在同一文件夹中

第二次更新答案：

您添加/引用的每个项目。请添加对Docker的支持。

这将更新docker文件。

Answer 3

您是否支持某种代理？公司或其他方式。

我可以通过在Dockerfile中设置http_proxy来解决此问题。

ARG HTTP_PROXY="http://username:password@proxy.example.com:8080"

下面的完整Dockerfile示例：

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build-env

WORKDIR /app

# Copy csproj and restore as distinct layers

COPY *.csproj ./

ARG HTTP_PROXY="http://username:password@proxy.example.com:8080"

USER administrator
RUN dotnet restore

# Copy everything else and build

COPY . ./

USER administrator
RUN dotnet publish -c Release -o out

# Build runtime image

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1

WORKDIR /app

COPY --from=build-env /app/out .

ENTRYPOINT ["dotnet", "myapp.dll"]