Kerberos // Failed to extract principal from ticket cache: Bad format in credentials cache

[mehd-io]

Hi there,
We got a clustered kerberos with SSL, and I basically used the same keytab that I'm using for other services to try out hdfs3 like this :

from hdfs3 import HDFileSystem
conf={'hadoop.security.authentication': 'kerberos'}
ticket_path='/home/dazer/mykey.keytab'
hdfs = HDFileSystem(host='hdfs://myhost', port=8020,pars=conf,ticket_cache=ticket_path)

and got the error :

ConnectionError: Connection Failed: HdfsIOException: FileSystem: Failed to extract principal from ticket cache: Bad format in credentials cache (filename: /home/dazer/mykey.keytab)

Any clue ?
Thx!

[martindurant]

A ticket cache is not the same as a keytab file. You should use the keytab file together withkinit to create a kerberos ticket, e.g., something like

kinit -k -t /home/dazer/mykey.keytab myprincipal@DOMAIN

and check what happened with klist, which will also tell you the location of the ticket cache (a directory).

[mehd-io]

Yeah you're right @martindurant sorry, just released that ! Got another problem now which is not really explicit :/ I'll investigate

/binaries/anaconda3/lib/python3.6/site-packages/hdfs3/core.py in __init__(self, host, port, connect, autoconf, pars, **kwargs)
     74 
     75         if connect:
---> 76             self.connect()
     77 
     78     def __getstate__(self):

/binaries/anaconda3/lib/python3.6/site-packages/hdfs3/core.py in connect(self)
    139         else:
    140             msg = ensure_string(_lib.hdfsGetLastError()).split('\n')[0]
--> 141             raise ConnectionError('Connection Failed: {}'.format(msg))
    142 
    143     def delegate_token(self, user=None):

ConnectionError: Connection Failed: Problem with callback handler

[martindurant]

Never saw that one before :| This message is also coming from the c-library layer, not the python library.

[mehd-io]

Actually, i got more logs info via the python shell as below :

2018-04-23 14:04:29.744451, p28387, th140584994699008, INFO Retrying connect to server: "afzera:8020". Already tried 9 time(s)
^[2018-04-23 14:04:34.936077, p28387, th140584994699008, ERROR Failed to setup RPC connection to "afzera:8020" caused by:
RpcChannel.cpp: 840: Problem with callback handler
	@	Hdfs::Internal::UnWrapper<Hdfs::SafeModeException, Hdfs::SaslException, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing>::unwrap(char const*, int)
	@	Hdfs::Internal::UnWrapper<Hdfs::AccessControlException, Hdfs::SafeModeException, Hdfs::SaslException, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing>::unwrap(char const*, int)
	@	Hdfs::Internal::UnWrapper<Hdfs::UnsupportedOperationException, Hdfs::AccessControlException, Hdfs::SafeModeException, Hdfs::SaslException, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing>::unwrap(char const*, int)
	@	Hdfs::Internal::UnWrapper<Hdfs::RpcNoSuchMethodException, Hdfs::UnsupportedOperationException, Hdfs::AccessControlException, Hdfs::SafeModeException, Hdfs::SaslException, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing>::unwrap(char const*, int)
	@	Hdfs::Internal::UnWrapper<Hdfs::NameNodeStandbyException, Hdfs::RpcNoSuchMethodException, Hdfs::UnsupportedOperationException, Hdfs::AccessControlException, Hdfs::SafeModeException, Hdfs::SaslException, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing, Hdfs::Internal::Nothing>::unwrap(char const*, int)

I noticed that ERROR Failed to setup RPC connection
and as said @quasiben by #91
and here : https://github.com/Pivotal-Data-Attic/attic-c-hdfs-client/issues/53
It's apparently due to the fact that hadoop.rpc.protection is set to privacy

I tried to overwrite this by :

conf={'hadoop.security.authentication': 'kerberos','hadoop.rpc.protection':'authenticate'}
hdfs = HDFileSystem(host='hdfs://myhost', port=8020,pars=conf,ticket_cache=ticket_path)

but still not working, does actually this stuff get overwritten by the core-site.xml ? Didn't set any global env however...

PS : I'm also running on cdh cluster but can't change core-site.xml

[martindurant]

To attempt to get "privacy" working, you could try installing https://anaconda.org/mdurant/libgsasl/1.8.1/download/linux-64/libgsasl-1.8.1-1.tar.bz2 explicitly - better do that in a clean environment. Note that you might also be interested in trying arrow's libhdfs native connector (no "3" in that name), which has closer integration with the java security infrastructure.