I would like to make TraceAdmin able to handle other config prefix such as "yarn.htrace.". I think SpanReceiverHost#addSpanReceiver is the right place to deal with the configs without prefix. Anyway we should file a new JIRA for that.
Yeah. The user should be able to set "-Clocal-file-span-receiver.path=/tmp/foo" on the YARN daemons and have it apply the relevant YARN htrace properties. There isn't any need to require the user to send '-Cyarn.htrace.local-file-span-receciver.path=...' We know that YARN tracing is what we want to configure, by virtue of the fact that the -host argument was for a YARN host.
The failure of TestHdfsConfigFields will be fixed in
HDFS-8371. It should be addressed as separate JIRA and I will update the patch once HDFS-8371 is committed.
+1 for v3, can you file a follow-on JIRA to talk about the prefix issue?