One liner for deleting images from a v2 docker registry

delete-from-v2-docker-registry.md

#!/usr/bin/env bash
# Credits (based on): J. Elliot Taylor https://gist.github.com/jaytaylor/86d5efaddda926a25fa68c263830dac1
# Changes:
# - iterate over tag list instead of using only first one
# - optional: basic auth

set -e
set -o pipefail

readonly VER=1.0.0
REGISTRY_URL='http://localhost:5000'
REGISTRY_CONTAINER=registry

# Remove the longest `*/` prefix
readonly SCRIPT_FULL_NAME="${0##*/}"

usage() {
  cat <<HEREDOC
NAME

    $SCRIPT_FULL_NAME -- remove the image(s) from the local Docker Registry

SYNOPSIS

    $SCRIPT_FULL_NAME [-r registry_url] [-c container] [-u user:password] image_name [tag 1] [tag 2] ...
    $SCRIPT_FULL_NAME -h: display this help

DESCRIPTION

    Removes the tagged image(s) from the local Docker Registry.

    The following options are available:

    image_name  image name in the Registry
    tag1 ...    (optional) remove specific tagged image. If not specified, remove **all** tagged images.

    -r registry_url (optional) Registry URL, defaults to $REGISTRY_URL
    -c container    (optional) Registry container name or id, defaults to \`$REGISTRY_CONTAINER\`
    -u              (optional) Registry credentials

ENVIRONMENT

    * Docker Registry container running locally.

EXAMPLES

        $ $SCRIPT_FULL_NAME my_app 1.4.1

v$VER
HEREDOC
  exit 1
}

# If a character is followed by a colon, the option is expected to have an argument
while getopts r:c:u:h OPT; do
  case "$OPT" in
    r)
      readonly REGISTRY_URL="$OPTARG"
      ;;
    c)
      readonly REGISTRY_CONTAINER=$OPTARG
      ;;
    u)
      readonly CRED_OPT=(--user "$OPTARG")
      ;;
    *) # -h or `?`: an unknown option
      usage
      ;;
  esac
done
echo -e "\n[$(date +'%T %Z') v$VER] ${USER:-${USERNAME:-${LOGNAME:-UID #$UID}}}@${HOSTNAME} ${PWD}> $0${*+ }$*\n"
shift $((OPTIND - 1))

# Process positional parameters
readonly IMAGE=$1
if [[ ! $IMAGE ]]; then
  usage
fi
shift

while (($# > 0)); do
  tags+=("$1")
  shift
done

if ((${#tags[@]} == 0)); then
  # Get tag list
  tag_list=$(curl "${CRED_OPT[@]}" --silent --show-error "${REGISTRY_URL}/v2/${IMAGE}/tags/list" | jq -r '.tags[]?')
  readarray -t tags <<<"$tag_list"
fi

# check for empty tag list, e.g. when already cleaned up
if ((${#tags[@]} == 0)); then
  echo "No $IMAGE images found"
  exit
fi

deleted=false
for tag in "${tags[@]}"; do
  image_digest=$(curl --head --header "Accept: application/vnd.docker.distribution.manifest.v2+json" "${CRED_OPT[@]}" \
      --silent --show-error "${REGISTRY_URL}/v2/${IMAGE}/manifests/${tag}" \
    | awk '$1 == "Docker-Content-Digest:" { print $2 }' \
    | tr -d $'\r'
  )
  if [[ $image_digest ]]; then
    echo "DELETING $IMAGE:$tag"
    curl --request DELETE "${CRED_OPT[@]}" --silent --show-error "${REGISTRY_URL}/v2/${IMAGE}/manifests/${image_digest}"
    deleted=true
    echo "DELETED $IMAGE:$tag"
  else
    echo "No $IMAGE:$tag image found"
  fi
done

if [[ $deleted == true ]]; then
  echo -e "\nCleaning up after deletion\n"
  # -m delete manifests that are not currently referenced via tag
  docker exec -it "$REGISTRY_CONTAINER" bin/registry garbage-collect /etc/docker/registry/config.yml -m

  echo -e "\nRestarting Registry"
  docker restart "$REGISTRY_CONTAINER"
fi