Is it possible to export that RUN --mount cache to a file that can be restored later?

General
1

Locally the Docker builds can be sped up using RUN –mount type=cache to cache dependency downloads. I was wondering if it is possible to export the current state of the cache mounts to a file that can be stored in the CI cache like the one in Azure DevOps.

2

Within the Dockerfile you can only control what is cached, and which RUN instruction should use cache.

You can configure BuildKit / buildx to use cache-to and cache-from and even leverage Azure Buckets:
https://docs.docker.com/reference/cli/docker/buildx/build/#cache-to
https://docs.docker.com/reference/cli/docker/buildx/build/#cache-from

General details:
https://docs.docker.com/build/cache/optimize/#use-an-external-cache

1 Like
4

yeah we don’t have azure buckets and the pipelines are very isolated (no AWS S3 buckets either). The closest I can do at the moment is push to the registry which is what I have done, but I am not sure about the “mechanics” of it. Does it get wiped on the next push if it is the same image etc.

So what I did was have push using the pattern:

  1. cache-<branch>

Then cache-from

  1. cache-master
  2. cache-<branch>