docker-registry-gc

#!/usr/bin/env sh

set -e

repositories=/var/lib/registry/docker/registry/v2/repositories/

printf 'Running Docker Registry garbage collection\n'
if ! docker container \
            exec \
            docker-registry_registry_1 \
            stat "$repositories" 2> /dev/null; then
  printf 'No repositories at %s\n' "$repositories"
  exit
fi

docker container \
       exec \
       docker-registry_registry_1 \
       registry \
       garbage-collect \
       /etc/docker/registry/config.yml

printf 'Deleting empty repositories\n'
# Delete directories where their _manifests/tags subdirectory is empty.
# Busybox find does not support -empty, emulate it using find and wc.
# After finding repos to delete we need to delete them in a second pass.
# The second pass is required because find of the first pass would try to
# traverse the directories we just deleted.
docker container \
       exec \
       docker-registry_registry_1 \
       find "$repositories" \
            -depth \
            -mindepth 1 \
            -type d \
            -path '*/_manifests/tags' \
            -exec sh -ec '[ $(find "$1" -maxdepth 1 -type d | wc -l) = 1 ] && printf "%s\0" "${1%_manifests/tags}"' - {} \; |
  xargs -0 \
        -r \
        -I{} \
        docker container \
               exec \
               docker-registry_registry_1 \
               rm -rf {}

# Delete empty directories.
docker container \
       exec \
       docker-registry_registry_1 \
       find "$repositories" \
            -depth \
            -mindepth 1 \
            -type d \
            -exec rmdir {} 2>/dev/null \;