recipes.md

crane Recipes

Useful tips and things you can do with crane and other standard tools.

Extract a single file from an image

crane export ubuntu - | tar -Oxf - etc/passwd

Note: Be sure to remove the leading / from the path (not /etc/passwd)

Bundle directory contents into an image

crane append -f <(tar -f - -c some-dir/) -t ${IMAGE}

By default, this produces an image with one layer containing the directory contents. Add -b ${BASE_IMAGE} to append the layer to a base image instead.

You can extend this even further with crane mutate, to make an executable in the appended layer the image's entrypoint.

crane mutate ${IMAGE} --entrypoint=some-dir/entrypoint.sh

Because crane append emits the full image reference, these calls can even be chained together:

crane mutate $(
  crane append -f <(tar -f - -c some-dir/) -t ${IMAGE}
) --entrypoint=some-dir/entrypoint.sh

This will bundle some-dir/ into an image, push it, mutate its entrypoint to some-dir/entrypoint.sh, and push that new image by digest.

Diff two configs

diff <(crane config busybox:1.32 | jq) <(crane config busybox:1.33 | jq)

Diff two manifests

diff <(crane manifest busybox:1.32 | jq) <(crane manifest busybox:1.33 | jq)