Dockerfile 在本地构建，但在 Azure Devops 管道中的 COPY 步骤失败

Question

我已经容器化了一个在 .net 框架 4.8 上运行的简单 Windows 服务。使用这个 dockerfile，应用程序和容器都可以在本地构建和运行：

FROM ourcontainerregistry.azurecr.io/net-framework-base:latest
WORKDIR /app

RUN cmd MSBuild.exe /property:Configuration=Release
COPY TopShelfServiceInstaller/bin/Release/ .

ENTRYPOINT ["TopShelfServiceInstaller.exe"]

当我在 docker 桌面本地连接到容器时，我在 C:/app 目录中看到了我期望的文件，并且可以确认服务正在按预期运行。

但是，当我尝试使用 Windows 最新的构建代理在 Azure Devops 的管道中运行此 dockerfile 时，我在 COPY 步骤中不断收到以下错误：

COPY failed: CreateFile \\?\C:\ProgramData\docker\tmp\docker-builder002424695\TopShelfServiceInstaller\bin\Release: The system cannot find the path specified.

任何想法为什么会发生这种情况以及我该如何解决？

编辑：用于构建的 azure-pipelines.yml：

resources:
  repositories:
    - repository: net-framework-base
      type: git
      name: Container_DotNetFrameworkBase
  containers:
    - container: net-framework-base
      type: ACR
      azureSubscription: ---
      resourceGroup: ---
      registry: ---
      repository: net-framework-base

variables:
  - name: dockerRegistryServiceConnection
    value: ---
  - name: imageRepository
    value: "service"
  - name: containerRegistry
    value: ---
  - name: prod-container-registry
    value: ---
  - name: dockerfilePath
    value: "$(Build.SourcesDirectory)/Service/dockerfile"
  - name: tag
    value: "$(Build.BuildNumber)"
  - name: vmImageName
    value: "windows-latest"
trigger:
  batch: true
  branches:
    include:
      - feature/*
#pr:
stages:
  - stage: container
    displayName: New Docker Build
    dependsOn: []
    jobs:
      - job: container
        displayName: build container
        pool:
          vmImage: $(vmImageName)
        steps:
          - checkout: self
            fetchDepth: 1
          - checkout: net-framework-base
            fetchDepth: 1

          # this is the task that's failing
          - task: Docker@2
            displayName: build container
            inputs:
              containerRegistry: $(prod-container-registry)
              repository: $(imageRepository)
              command: "build"
              Dockerfile: $(dockerfilePath)
              tags: |
                $(tag)

Answer 1

我认为COPY 命令不会像您认为的那样做。 COPY 将文件从主机文件系统复制到容器中。它在本地工作的原因是因为您已经在本地构建了代码，所以它将您在本地构建的版本复制到容器中。

您应该做的是COPY将源代码放入容器中，然后运行构建应用程序所需的任何步骤。使用multi-stage builds 也是一个很好的做法：您将源代码复制到带有 SDK 和构建工具链的容器中，构建它，然后将生成的输出复制到一个精简的运行时容器中，该容器只包含一个运行时环境没有源代码。

Answer 2

我想添加另一个答案，以更好地解释我的问题是什么以及我是如何解决的。我的问题不是对 COPY 命令的误解，而是对在哪里构建的内容的误解。这是旧的 dockerfile，其中解释了我哪里出错了：

FROM ourcontainerregistry.azurecr.io/net-framework-base:latest
WORKDIR /app

# As Daniel said, the reason it was working for me locally is because I had already built the solution from visual studio.
# So this command wasn't actually building anything because nothing existed on this container yet.
RUN cmd MSBuild.exe /property:Configuration=Release

# However, this was copying the files I had already built in VS locally.
# When this ran on the build agent in Azure DevOps, it would fail because the solution had not been built on the build agent.
COPY TopShelfServiceInstaller/bin/Release/ .

ENTRYPOINT ["TopShelfServiceInstaller.exe"]

这是我的新 dockerfile，它使用带有 cmets 的多阶段构建，讲述了发生的时间和原因：

# First stage is building the app.  
# We do this with one container based on the .NET Framework 4.8 image that has the SDK installed on it.
FROM mcr.microsoft.com/dotnet/framework/sdk:4.8-windowsservercore-ltsc2019 AS build
WORKDIR C:/build

# Next we copy all files from the host into the build container.
COPY . .

# Then we run MSBuild to build the solution.
RUN MSBuild.exe /property:Configuration=Release

# Next and last stage is creating a container that will actually run the app.
FROM ourcontainerregistry.azurecr.io/net-framework-base:latest AS runtime
WORKDIR C:/app

# And here we're copying files from the build container into the runtime container.
COPY --from=build C:/build/TopShelfServiceInstaller/bin/Release .

ENTRYPOINT [ "C:/app/TopShelfServiceInstaller.exe" ]

以这种方式构建的要点在于，它允许您克隆存储库并使用单个命令构建容器，无论您是在本地工作还是在自动构建管道中运行它，正如 Daniel 所提到的那样。