This container can be pulled via:
  docker pull registry.opensuse.org/home/mwilck/containers/sle_12_sp5/build-kernel:0.2
  docker pull registry.opensuse.org/home/mwilck/containers/sle_12_sp5/build-kernel:0.2.11.68
  docker pull registry.opensuse.org/home/mwilck/containers/sle_12_sp5/build-kernel:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.