add SET_CACHE_MOUNTS_ENV

[idelvall]

Adds

• +SET_CACHE_MOUNTS_ENV: that sets two entries in the environment with the code for the cache mounts.
• +COPY_OUTPUT: to copy files from the the target mount cache to the image layers

This new approach gives more flexibility, for example to run within a WITH DOCKER clause:

Example:

build:
  ...
  DO rust+SET_CACHE_MOUNTS_ENV
  WITH DOCKER
    RUN --mount=$EARTHLY_RUST_CARGO_HOME_CACHE --mount=$EARTHLY_RUST_TARGET_CACHE  cross build --target $TARGET --release
  END
 

[joepio]

Works for me!

[joepio]

I noticed I'm no longer able to use GET_RUST_CACHE_MOUNTS. I though maybe it was renamed to SET_CACHE_MOUNTS_ENV, so I updated my earthly file (see below), but that also does not work. It does not seem to create an artifact.

Maybe I'm missing something?

atomicdata-dev/atomic-server#805

cross-build:
  FROM +source
  ARG --required TARGET
  DO rust+SET_CACHE_MOUNTS_ENV
  WITH DOCKER
    RUN --mount=$EARTHLY_RUST_CARGO_HOME_CACHE --mount=$EARTHLY_RUST_TARGET_CACHE  cross build --target $TARGET --release
  END
  SAVE ARTIFACT ./target/$TARGET/release/atomic-server AS LOCAL artifact/bin/atomic-server-$TARGET

[idelvall]

Hi @joepio, given that target folder is within the mount cache, so you need to copy the output files first to the target layers, so it can be retrieved with SAVE ARTIFACT later on.
You can use +COPY_OUPUT target for that purpose: https://github.com/earthly/lib/blob/main/rust/README.md#copy_output

[joepio]

@idelvall I can't get rust+COPY_OUTPUT to actually copy anything.

Even with DO rust+COPY_OUTPUT --output="*" my ./target directory seems completely empty.

Am I missing something?

cross-build:
  FROM +source
  ARG --required TARGET
  DO rust+SET_CACHE_MOUNTS_ENV
  WITH DOCKER
    RUN --mount=$EARTHLY_RUST_CARGO_HOME_CACHE --mount=$EARTHLY_RUST_TARGET_CACHE  cross build --target $TARGET --release
  END
  DO rust+COPY_OUTPUT --output="*"
  RUN ./target/$TARGET/release/atomic-server --version
  SAVE ARTIFACT ./target/$TARGET/release/atomic-server AS LOCAL artifact/bin/atomic-server-$TARGET

logs: https://cloud.earthly.dev/builds/2227c1db-854b-4b3a-a3d0-ca012c0a9873

[idelvall]

That argument is actually a regexp @joepio.
Try starting with --output=".*" and then making it more specific, so only the files of your interest are copied

[joepio]

Ah yes, thanks!

One step further :)