SOLVED:ERROR nova.virt.libvirt.driver [-] Connection to libvirt failed: Failed to connect socket to '/var/run/libvirt/libvirt-sock' No such file or directory

Fix:
====
a)
Find libvirt group
$ cat /etc/group | grep lib
libuuid:x:101:
libvirtd:x:113:stackuser,saju

b)
Edit  /etc/libvirt/libvirtd.conf
sudo vim /etc/libvirt/libvirtd.conf
unix_sock_group = "libvirtd"

c)
$ cat /etc/libvirt/libvirtd.conf | grep ^[^#]
unix_sock_group = "libvirtd"
unix_sock_rw_perms = "0770"
auth_unix_ro = "none"
auth_unix_rw = "none"

d)
Restart
sudo service libvirt-bin restart
 
Error
======
2014-04-18 01:24:15.803 ERROR nova.virt.libvirt.driver [-] Connection to libvirt failed: Failed to connect socket to '/var/run/libvirt/libvirt-sock'
: No such file or directory
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver Traceback (most recent call last):
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver   File "/opt/stack/nova/nova/virt/libvirt/driver.py", line 677, in _connect
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver     return libvirt.openAuth(uri, auth, flags)
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver   File "/usr/lib/python2.7/dist-packages/libvirt.py", line 102, in openAuth
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver     if ret is None:raise libvirtError('virConnectOpenAuth() failed')
2014-04-18 01:24:15.803 TRACE nova.virt.libvirt.driver libvirtError: Failed to connect socket to '/var/run/libvirt/libvirt-sock': No such file or directory

Error
=====
2014-04-17 20:14:50.100+0000: 57679: info : libvirt version: 1.2.3
2014-04-17 20:14:50.100+0000: 57679: error : virGetGroupID:994 : invalid argument: Failed to parse group 'libvirt'