This container can be pulled via:
  docker pull registry.opensuse.org/isv/rancher/elemental/staging/containers/suse/sl-micro/6.1/base-os-container:2.2.1
  docker pull registry.opensuse.org/isv/rancher/elemental/staging/containers/suse/sl-micro/6.1/base-os-container:2.2.1-17.6
  docker pull registry.opensuse.org/isv/rancher/elemental/staging/containers/suse/sl-micro/6.1/base-os-container:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.