EUCAFATAL Failed to connect to xen:///

EUCAFATAL  Failed to connect to xen:///

I work with Eucalyptus 2.0.3. I registered my Node Controller with a Cluster Controller. Even though it got successfully added and Node Controller was working, The Cores of that NC was not added and shown in
euca-describe-availability-zones verbose

I checked nc.log . It was showing following error.


[EUCAFATAL ] Failed to connect to xen:///
[EUCAFATAL ] ERROR: failed to initialized hypervisor driver!

So I logged inside NC and tried to execute virsh under eucalyptus account

su eucalyptus
virsh list

First time No response in terminal. The next time I got the following error

error: Failed to reconnect to the hypervisor
error: no valid connection
error: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Permission denied

I just added eucalyptus user to libvirt group

adduser eucalyptus libvirt

When I tried virsh under eucalyptus, it was working.