mirror-docker-images.sh

#!/bin/bash

if [ $# -lt 2 ]; then
  echo Usage: $0 NEW-REGISTRY NEW-OWNER [push]
  exit 1
fi

new_registry="$1"
new_owner="$2"
push="$3"

docker images --format '{{.Repository}}:{{.Tag}}' \
  | grep -E '^(docker.io|quay.io|ghcr.io|k8s.gcr.io)/' \
  | grep -v ':<none>$' \
  | sort -u \
| while read image; do
 # registry/image:tag
  image_name=${image#*/}
  image_name=${image_name%:*}
  image_tag=${image##*:}

  if [[ $image =~ [^/]+/[^/]+/[^/]+:.* ]]; then
    # registry/owner/image:tag
    image_name=${image_name%/*}_${image_name#*/}
  fi
  new_image=$new_registry/$new_owner/$image_name:$image_tag
  if [ "$push" == push ]; then
    docker tag $image $new_image
    docker push $new_image
  else
    echo docker tag $image $new_image
    echo docker push $new_image
  fi
done