RpcConnectionRegistry was introduced in 2.5.0, and since it reduces the load of zookeeper, I believe it has already been used by lots of users. We have already known that it can not work well with token(digest) based authentication, and have already filed HBASE-25051 for it. and recently, when fixing HBASE-28316, we found out that it could also be broken if we choose to use different server principals for master and region server, see HBASE-28321 for more details. Since this is a very important feature and should have been widely used among our users, I think we should fix these issues ASAP. I've already worked on HBASE-25051 for a while and provided a workable solution[1], so this time I took a deep thought and put up a design doc[2], to address both HBASE-25051 and HBASE-28321.
Please take a look. Any comments here or on the design doc are welcomed. Thanks. 1. https://github.com/apache/hbase/pull/5631 2. https://docs.google.com/document/d/1Cu-qzAdBGyBKM07aQP06RM0oeFSLPGtQFWuV_TDyBNg/edit?usp=sharing
