Cache mounts without persisting cache folder in Docker image

[ralbertazzi]

Hi there 👋 I started playing with cache mounts (RUN --mount=type=cache) but something that I'm failing to understand is how/if it's possible to avoid persisting the cache folder in the final image. Let's take an example from the buildkit reference:

RUN --mount=type=cache,target=/var/cache/apt,sharing=locked \
  --mount=type=cache,target=/var/lib/apt,sharing=locked \
  apt update && apt-get --no-install-recommends install -y gcc

How can I exploit the caching functionalities without having /var/cache/apt and /var/lib/apt in my final image? I guess one solution could be using multi-stage builds (use cache mounts in first stage, copy artifacts in second stage) but I'm wondering if this is always possible - for instance if you want to install some apt packages in the final stage I guess you'd have to leave with the cache being there.

Am I missing some other workaround?