docker build cleanup

docker-orphan.sh

#!/usr/bin/env bash

# see https://lebkowski.name/docker-volumes/
# The command doesn’t remove anything, but simply passing the results to xargs -r rm -fr does so.
find '/var/lib/docker/volumes/' -mindepth 1 -maxdepth 1 -type d | grep -vFf <(
  docker ps -aq | xargs docker inspect | jq -r '.[]|.Mounts|.[]|.Name|select(.)'
)

# Hint: docker 1.9 has new volume management system, so it’s way easier with this version:
# docker volume ls -qf dangling=true | xargs -r docker volume rm