Correct way to use registry cache with mode=max when using bake to build multiple targets with shared stages

[radusuciu]

The title to my question is a bit of a mouthful, so perhaps an example will make this most clear. I've got a Dockerfile that is used to build several variants of a Python application

The below Dockerfile defines two images production and development which share a common runtime base stage and copy their dependencies from related build stages. As I understand it, in this situation, when using registry cache, it is recommended to use the max mode, so as to cache intermediate stages.

The question yes: is there any harm in using mode=max for both production and development? Would it be more correct to use mode=max for development which adds to production and mode=min for production?

### runtime-base: contains minimal common dependencies ###
FROM python:3.11.9-slim-bullseye AS runtime-base
ENV VIRTUAL_ENV=/venv
RUN apt-get install -yq build-essential


### build stages ###
FROM runtime-base AS production-build
RUN pip install pdm
COPY pyproject.toml pdm.lock .
WORKDIR /build
RUN pdm sync

FROM production-build AS development-build
RUN pdm sync --dev


### runtime stages ###
FROM runtime-base AS production
COPY --from=production-build ${VIRTUAL_ENV} ${VIRTUAL_ENV} 

FROM runtime-base AS development
COPY --from=development-build ${VIRTUAL_ENV} ${VIRTUAL_ENV} 

An example bake file to go with the above.

target "production" {
  dockerfile = "Dockerfile"
  context = "."
  target = "production"
  cache-to =  ["type=registry,ref=ghcr.io/my_repo/cache__production,mode=max"]
  cache-from = ["type=registry,ref=ghcr.io/my_repo/cache__production"]
}

target "production" {
  dockerfile = "Dockerfile"
  context = "."
  target = "production"
  cache-to =  ["type=registry,ref=ghcr.io/my_repo/cache__development,mode=max"]
  cache-from = ["type=registry,ref=ghcr.io/my_repo/cache__development"]
}

Thanks!