docker-registry-cache.py

# Usage
#
#    tutor plugins install https://gist.githubusercontent.com/regisb/4049622ec4b48cbd48c89ec708dc5252/raw/docker-registry-cache.py
#    tutor plugins enable docker-registry-cache
#
# Cache will automatically be pulled from registry when you run:
#
#     tutor images build openedx
#
# You can also push after building:
#
#     tutor images build --docker-arg=push-cache openedx

from __future__ import annotations
from tutor import hooks


@hooks.Filters.DOCKER_BUILD_COMMAND.add()
def _cache_from(command: list[str]) -> list[str]:
    if command[0] not in ("build", "buildx"):
        return command

    # Use buildkit
    if command[0] != "buildx":
        command.insert(0, "buildx")

    # Find the image tag
    tag_arg = "-t" if "-t" in command else "--tag"
    try:
        tag_arg_index = command.index(tag_arg)
    except ValueError:
        # it's weird but we didn't find the tag
        return command

    # Add the --cache-from args
    tag = command[tag_arg_index + 1]
    # Use the image tag to determine the cache image tag
    command.insert(tag_arg_index, f"--cache-from=type=registry,ref={tag}-cache")

    # Do we also want to push the cache to the registry?
    if "push-cache" in command:
        command[
            command.index("push-cache")
        ] = f"--cache-to=type=registry,mode=max,ref={tag}-cache"

    # Add image to docker
    command.insert(tag_arg_index, "--load")

    return command