This container can be pulled via:
  docker pull registry.opensuse.org/devel/bci/sle-15-sp7/containerfile/suse/alertmanager:0.28
  docker pull registry.opensuse.org/devel/bci/sle-15-sp7/containerfile/suse/alertmanager:0.28.1
  docker pull registry.opensuse.org/devel/bci/sle-15-sp7/containerfile/suse/alertmanager:0.28.1-240.1
  docker pull registry.opensuse.org/devel/bci/sle-15-sp7/containerfile/suse/alertmanager:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.