How to Enable Docker layer caching in Azure DevOps

Question

I am running the below yaml script to build docker images and push into kubernetes cluster but at the same time I wanted to enable docker layer caching in the azure DevOps while

Answer 1

Edit: as pointed out in the comments, this feature is actually available without BuildKit. There's an example here on how to use a Docker image as the cache source during a build.

By adding the variable DOCKER_BUILDKIT: 1 (see this link) to the pipeline job and installing buildx, I managed to achieve layer caching by storing the cache as a separate image. See this link for some basics

Here's an example step in Azure DevOps

- script: |
    image="myreg.azurecr.io/myimage"
    tag=$(Build.SourceBranchName)-$(Build.SourceVersion)
    cache_tag=cache-$(Build.SourceBranchName)

    docker buildx create --use
    docker buildx build \
      -t "${image}:${tag}"
      --cache-from=type=registry,ref=${image}:${cache_tag}\
      --cache-to=type=registry,ref=${image}:${cache_tag},mode=max \
      --push \
      --progress=plain \
      .
  displayName: Build & push image using remote BuildKit layer cache

This of course will require each run to download the image cache, but for images that have long-running installation steps in the Docker build process this is definitely faster (in our case from about 8 minutes to 2).