I can add a new config property or maybe a new fsck CLI option "-upgradedomains" (similar to "-replicadetails") is better. That was my initial plan too. But I still wondered if that is necessary.
The users has already explicitly opted in for this information to some degree, given users has to set dfs.namenode.hosts.provider.classname to CombinedHostFileManager with proper json file in order to config upgrade domains. In addition users have to specify fsck CLI option like "-replicadetails" to display it.
If down the road we need to add more properties to DN, does it mean we need to add new fsck CLI option for each one of those, or can we use something more general like "-replicadetails"?
Also as mentioned above, I am not sure how fsck output can maintain strict compatibility when the block placement policy is changed via dfs.block.replicator.classname.