This container can be pulled via:
  docker pull registry.opensuse.org/home/dcassany/unifiedcore/tumbleweed/containers/elemental3ctl-sysext:0_1.28-5.67
  docker pull registry.opensuse.org/home/dcassany/unifiedcore/tumbleweed/containers/elemental3ctl-sysext:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.