NiFi Registry: No available buckets
Caused
NiFi Registry unable to recognized NiFi node identity when try to connect.
Resolution
Add a new user for each NiFi node (node user is derived from the NiFi nodes certificate DNs) in your compute cluster on the NiFi Registry UI and Ranger
Add either the "nifiregistry" group or all NiFi node users to the following NiFi Registry policies in Ranger:
/buckets policy with Read permissions
/proxy policy with Read, Write, and Delete permissions
