This container can be pulled via:
  docker pull registry.opensuse.org/home/dancermak/bci/tumbleweed/containerfile/suse/alertmanager:0.23.0
  docker pull registry.opensuse.org/home/dancermak/bci/tumbleweed/containerfile/suse/alertmanager:0.23.0-1.3
  docker pull registry.opensuse.org/home/dancermak/bci/tumbleweed/containerfile/suse/alertmanager:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.