This container can be pulled via:
  docker pull registry.opensuse.org/isv/rancher/elemental/devgit/containers/rancher/elemental-channel/sl-micro:6.0-base
  docker pull registry.opensuse.org/isv/rancher/elemental/devgit/containers/rancher/elemental-channel/sl-micro:6.0-base-3.1

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.