This container can be pulled via:
  docker pull registry.opensuse.org/devel/kubic/containers/container/kubic/flannel:0.28.4
  docker pull registry.opensuse.org/devel/kubic/containers/container/kubic/flannel:0.28.4-31.533
  docker pull registry.opensuse.org/devel/kubic/containers/container/kubic/flannel:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.