Storm would like to be able to fetch delegation tokens and forward them on to running topologies so that they can access HDFS (
STORM-346). But to do so we need to open up access to some of APIs.
Most notably FileSystem.addDelegationTokens(), Token.renew, Credentials.getAllTokens, and UserGroupInformation but there may be others.
At a minimum adding in storm to the list of allowed API users. But ideally making them public. Restricting access to such important functionality to just MR really makes secure HDFS inaccessible to anything except MR, or tools that reuse MR input formats.