This container can be pulled via:
  docker pull registry.opensuse.org/home/defolos/bci/cr/sle-15-sp4/containerfile/suse/alertmanager:0.23.0
  docker pull registry.opensuse.org/home/defolos/bci/cr/sle-15-sp4/containerfile/suse/alertmanager:0.23.0-2.195
  docker pull registry.opensuse.org/home/defolos/bci/cr/sle-15-sp4/containerfile/suse/alertmanager:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.