Docker构建抱怨它无法找到nuget fallback包文件夹

Posted 2021-04-12

我正在学习https://docs.microsoft.com/en-us/dotnet/core/docker/docker-basics-dotnet-core#dockerize-the-net-core-application的教程，学习将.net核心应用程序容纳到Docker中。

除了将Dockerfile更改为指向microsoft/dotnet:2.1-sdk作为基本图像，并添加RUN dotnet --info线以获取版本/环境信息之外，其他所有内容都是相同的。但是，我在dotnet publish步骤中收到错误：

Step 7/8 : RUN dotnet publish -c Release -o out
 ---> Running in 6739267c7581
Microsoft (R) Build Engine version 15.8.166+gd4e8d81a88 for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  Restore completed in 34.46 ms for /app/Hello.csproj.
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018: The "ResolvePackageAssets" task failed unexpectedly. [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018: NuGet.Packaging.Core.PackagingException: Unable to find fallback package folder 'C:Program FilesdotnetsdkNuGetFallbackFolder'. [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at NuGet.Packaging.FallbackPackagePathResolver..ctor(String userPackageFolder, IEnumerable`1 fallbackPackageFolders) [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.NuGetPackageResolver.CreateResolver(LockFile lockFile, String projectPath) [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheWriter..ctor(ResolvePackageAssets task, Stream stream) [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader.CreateReaderFromDisk(ResolvePackageAssets task, Byte[] settingsHash) [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader..ctor(ResolvePackageAssets task) [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ReadItemGroups() [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ExecuteCore() [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.NET.Build.Tasks.TaskBase.Execute() [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute() [/app/Hello.csproj]
/usr/share/dotnet/sdk/2.1.401/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(198,5): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask) [/app/Hello.csproj]
The command '/bin/sh -c dotnet publish -c Release -o out' returned a non-zero code: 1

到目前为止，我唯一能找到的主题是一些github问题，要求将后备文件夹丢弃在Docker中，因为它会使容器膨胀。在这个阶段，我并不太关心臃肿，我只是想让它构建一个hello world应用程序。

---

如果它有用，dotnet --info命令返回以下内容：

Step 3/8 : RUN dotnet --info
 ---> Running in 17dad2f04a7e
.NET Core SDK (reflecting any global.json):
 Version:   2.1.401
 Commit:    91b1c13032

Runtime Environment:
 OS Name:     debian
 OS Version:  9
 OS Platform: Linux
 RID:         debian.9-x64
 Base Path:   /usr/share/dotnet/sdk/2.1.401/

Host (useful for support):
  Version: 2.1.3
  Commit:  124038c13e

.NET Core SDKs installed:
  2.1.401 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.3 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.1.3 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.3 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

答案

这可能是由于在打开项目时由Visual Studio生成的objproject.assests.json文件。如果您查看，您将在Windows系统中找到对NuGet包文件夹的引用。

EG

"packageFolders": {
  "C:\Users\<UserName>\.nuget\packages\": {},
  "C:\Program Files\dotnet\sdk\NuGetFallbackFolder": {}
},

一个简单的解决方法是在Dockerfile中添加一个步骤，以便在运行任何恢复，构建或测试步骤之前删除bin和obj文件。一种方法是使用find程序：

find -type d -name bin -prune -exec rm -rf {} ; && find -type d -name obj -prune -exec rm -rf {} ;

使用您链接的教程中的Dockerfile作为示例，看起来像这样：

FROM microsoft/dotnet:2.1-sdk
WORKDIR /app

# copy csproj and restore as distinct layers
COPY *.csproj ./
RUN dotnet restore

# copy and build everything else
COPY . ./
RUN find -type d -name bin -prune -exec rm -rf {} ; && find -type d -name obj -prune -exec rm -rf {} ;
RUN dotnet publish -c Release -o out
ENTRYPOINT ["dotnet", "out/Hello.dll"]