It seems we can use /usr/share/openstack-tripleo-heat-templates/environments/storage-environment.yaml to determine if we use ceph as storage backend or not. But the yaml configuration file is simple and we don't figure out how it works and generate the final cinder/nova/glance configuration files. If we want to extend this configuration, where should we look at?

[1] https://repos.fedorapeople.org/repos/openstack-m/rdo-manager-docs/liberty/basic_deployment/basic_deployment_cli.html