This container can be pulled via:
  docker pull registry.opensuse.org/devel/caasp/1.0/standard/kubic/salt-master:2018.3
  docker pull registry.opensuse.org/devel/caasp/1.0/standard/kubic/salt-master:2018.3.0
  docker pull registry.opensuse.org/devel/caasp/1.0/standard/kubic/salt-master:2018.3.0-21.22

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.