It is not documented right now which Newts configurations can be done with confd in Docker based OpenNMS installations.
These configurations are available right now: https://github.com/OpenNMS/opennms/blob/develop/opennms-container/horizon/container-fs/confd/templates/newts.properties.tpl
For the Minion container we already have the options documented (at least in a markdown file) as you can see here: https://github.com/OpenNMS/opennms/blob/develop/opennms-container/minion/CONFD_README.md
We can do it the same for the Horizon container. The file
is not existing right now, but will exist when merging https://github.com/OpenNMS/opennms/pull/3205.