This container can be pulled via:
  docker pull registry.opensuse.org/home/defolos/bci/staging/sle-15-sp4/sle15-sp4-ojpvj/containerfile/suse/alertmanager:0.23.0
  docker pull registry.opensuse.org/home/defolos/bci/staging/sle-15-sp4/sle15-sp4-ojpvj/containerfile/suse/alertmanager:0.23.0-1.98

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.