Why "Error loading column family" in OpsCenter when reading Column Family? - cassandra

Question

I'm trying to use the OpsCenter with my local multi-node development cluster created with CCM. I have manually installed and configured the Agents for each node using these instructions. I created my custom keyspace and its column families by uploading a SOURCE file in the CQLSH interface
I get the following error when clicking on Data > MyKeySpace > MyColumnFamily:
Error loading column family: Call to /test_cluster/keyspaces/flashcardsapp/cf/tag timed out.
I am however able to view the column families in the OpsCenter keyspace.
I am seeing the following in the OpsCenter log:
2015-03-14 07:58:35-0600 [] Unhandled Error
Traceback (most recent call last):
File "/Users/justinrobbins/Documents/dev/cassandra/opscenter-5.1.0/lib/py-osx/2.7/amd64/twisted/internet/defer.py", line 1076, in gotResult
_inlineCallbacks(r, g, deferred)
File "/Users/justinrobbins/Documents/dev/cassandra/opscenter-5.1.0/lib/py-osx/2.7/amd64/twisted/internet/defer.py", line 1063, in _inlineCallbacks
deferred.callback(e.value)
File "/Users/justinrobbins/Documents/dev/cassandra/opscenter-5.1.0/lib/py-osx/2.7/amd64/twisted/internet/defer.py", line 361, in callback
self._startRunCallbacks(result)
File "/Users/justinrobbins/Documents/dev/cassandra/opscenter-5.1.0/lib/py-osx/2.7/amd64/twisted/internet/defer.py", line 455, in _startRunCallbacks
self._runCallbacks()
--- <exception caught here> ---
File "/Users/justinrobbins/Documents/dev/cassandra/opscenter-5.1.0/lib/py-osx/2.7/amd64/twisted/internet/defer.py", line 542, in _runCallbacks
current.result = callback(current.result, *args, **kw)
File "build/lib/python2.7/site-packages/opscenterd/TwistedRouter.py", line 226, in controllerSucceeded
File "build/lib/python2.7/site-packages/opscenterd/WebServer.py", line 3953, in default_write
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/__init__.py", line 250, in dumps
sort_keys=sort_keys, **kw).encode(obj)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 207, in encode
chunks = self.iterencode(o, _one_shot=True)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 270, in iterencode
return _iterencode(o, 0)
File "build/lib/python2.7/site-packages/opscenterd/WebServer.py", line 261, in default
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/json/encoder.py", line 184, in default
raise TypeError(repr(o) + " is not JSON serializable")
exceptions.TypeError: UUID('457d5450-ca0b-11e4-a99a-53fff8597215') is not JSON serializable
My environment is as follows:
Cassandra: dsc-cassandra-2.1.2
OpsCenter: opscenter-5.1.0
Agents: datastax-agent-5.1.0
OS: OSX 10.10.1

Answer 1

There’s a known bug in OpsCenter where UUID columns in Cassandra 2.1.x are not handled properly. I am not aware of any workarounds (switching from UUID columns or downgrading C* to 2.0.x should work, but it might be a bit too much work.)
It’s going to be fixed in the upcoming patch release of OpsCenter 5.1 (not 5.1.1 though)