Cache builder so we don't have to pull it all the time

[ryanjbaxter]

No description provided.

[wind57]

may be we should also cache the .launch cache:

CACHE_VOLS=$(docker volume ls --format '{{.Name}}' | grep 'pack-cache.*\.\(build\|launch\)$' || true)

[wind57]

I think we can do spin an alpine image only once per all volumes:

        mkdir -p /tmp/pack-volumes

        VOLUME_MOUNTS=""
         for vol in $CACHE_VOLS; do
           echo "Saving pack cache volume: $vol"
          VOLUME_MOUNTS="$VOLUME_MOUNTS -v $vol:/in/$vol"
         done

        # mount all selected Docker cache volumes into one helper container
        # loop over them
        # compress each one into its own tar.gz file
        # place those tar.gz files in /tmp/pack-volumes on the host
        # each volume becomes : /tmp/pack-volumes/pack-cache-foo.build.tar.gz on the host 

        docker run --rm \
          $VOLUME_MOUNTS \
          -v /tmp/pack-volumes:/out \
          alpine sh -c '
            for dir in /in/*; do
              vol=$(basename "$dir")
              tar czf "/out/${vol}.tar.gz" -C "$dir" .
            done
          '

[wind57]

 - name: load pack cache into docker volumes
   shell: bash
   if: steps.pack-cache-restore.outputs.cache-hit == 'true'
   run: |
     if [ -d /tmp/pack-volumes ] && [ "$(ls -A /tmp/pack-volumes/*.tar.gz 2>/dev/null)" ]; then
      VOLUME_MOUNTS=""
       for f in /tmp/pack-volumes/*.tar.gz; do
         vol=$(basename "$f" .tar.gz)
         echo "Restoring pack cache volume: $vol"
         docker volume create "$vol" 2>/dev/null || true
        VOLUME_MOUNTS="$VOLUME_MOUNTS -v $vol:/out/$vol"
       done

      # iterate over every cached archive file restored from GitHub Actions cache
      # strip path and .tar.gz
      # extract that archive into the mounted Docker volume director

      docker run --rm \
        -v /tmp/pack-volumes:/in \
        $VOLUME_MOUNTS \
        alpine sh -c '
          for tar_file in /in/*.tar.gz; do
            vol=$(basename "$tar_file" .tar.gz)
            tar xzf "$tar_file" -C "/out/$vol"
          done
        '
     else
       echo "No pack cache volumes found to restore"
     fi

[wind57]

@ryanjbaxter if you don't have the time, I can pick this up, its a good enhancement. wdyt?

[ryanjbaxter]

Yes that would be great! I am swamped with other things. I am trying to solve the annoying issue where CI builds on github actions fails with the error code 51. I am sure you have seen that.

[wind57]

ok, you can close this one then. I started working on it.