添加如下代码到Docker任务中以启用缓存：

- task: Docker@2
  displayName: 'Build and push an image to container registry'
  inputs:
    command: buildAndPush
    repository: $(dockerRegistry)/$(imageRepository)
    dockerfile: $(dockerfilePath)
    buildContext: $(buildContext)
    tags: |
      $(tag)
    arguments: $(dockerBuildArguments)
  continueOnError: true
  env:
    DOCKER_CLI_EXPERIMENTAL: enabled
  timeoutInMinutes: 20
  condition: eq(variables['Build.SourceBranch'], 'refs/heads/master')
  options: '--mount=type=cache,target=/root/.cache/docker-build --mount=type=cache,target=/root/.cache/go-build'

这段代码中，我们使用了“mount”参数，其中包含了两个挂载路径：一个是/docker-build，用于Docker镜像缓存，另一个是/go-build，用于Go语言编译缓存。语句中的“target”参数指定了缓存保存在Docker主机上的路径，从而有充分利用主机本地的缓存。

此外，还需在yml文件顶部声明以下变量：

variables:
  DOCKER_CACHE_MOUNT_PATH: $(Agent.WorkFolder)/docker-cache
  GO_CACHE_MOUNT_PATH: $(Agent.WorkFolder)/go-cache

完整的修改后的yml文件应如下所示：

steps:
- task: Docker@2
  displayName: 'Build and push an image to container registry'
  inputs:
    command: buildAndPush
    repository: $(dockerRegistry)/$(imageRepository)
    dockerfile: $(dockerfilePath)
    buildContext: $(buildContext)
    tags: |
      $(tag)
    arguments: $(dockerBuildArguments)
  continueOnError: true
  env:
    DOCKER_CLI_EXPERIMENTAL: enabled
  timeoutInMinutes: 20
  condition: eq(variables['Build.SourceBranch'], 'refs/heads/master')
  options: '--mount=type=cache,target=/root/.cache/docker-build --mount