This is a bug that should have been fixed in Ambari 2.4 but showed up too late in the release and has repercussions to test it.
Basically, status_params.py for Atlas service in Ambari sets
This is technically incorrect since /etc/atlas/conf is a symlink to /usr/hdp/current/atlas-client/conf, which is then a symlink to /etc/atlas/$some_version/0
During Rolling Upgrade,
1. Atlas Server is stopped, new configs are written to /etc/atlas/$new_version/0, then symlink is changed so that /usr/hdp/current/atlas-server points to new version, and Atlas Server is started
At this point, /etc/atlas/conf -> /usr/hdp/current/atlas-client/conf (which is still using the old version) since the client has not yet been updated.
2. Atlas Client has new configs written to /etc/atlas/$new_version/0, then symlink is changed so that /usr/hdp/current/atlas-client points to new version
Basically, we need to look at the usages of conf_dir and make sure it is correct during all scenarios.