This container can be pulled via:
  docker pull registry.opensuse.org/devel/bci/tumbleweed/containerfile/opensuse/kiosk-firefox:138.0
  docker pull registry.opensuse.org/devel/bci/tumbleweed/containerfile/opensuse/kiosk-firefox:138.0-15.8
  docker pull registry.opensuse.org/devel/bci/tumbleweed/containerfile/opensuse/kiosk-firefox:latest

Set DOCKER_CONTENT_TRUST=1 to enable image tag verification.