Am installing Openstack mitaka (single Ubuntu 14 vm - all in one controller with neutron linuxbridge) deploying through the ansible playbooks. Once the deployment is completed am able to see the services (nova, neutron etc )are active. But when i try to launch an instance, vm is getting to ERROR state. The nova-compute logs shows error as follows:

2016-11-07 12:43:42.892 30047 INFO nova.service [-] Starting compute node (version 13.1.1)
2016-11-07 12:43:42.899 30047 INFO nova.virt.libvirt.driver [-] Connection event '0' reason 'Failed to connect to libvirt'
2016-11-07 12:43:42.923 30047 WARNING nova.virt.libvirt.driver [req-4678f654-469f-4085-a409-7a17b01d6674 - - - - -] Cannot update service status on host "controller" since it is not registered.
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host [req-4678f654-469f-4085-a409-7a17b01d6674 - - - - -] Connection to libvirt failed: Failed to connect socket to '/var/run/libvirt/libvirt-sock': Permission denied
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host Traceback (most recent call last):
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/host.py", line 528, in get_connection
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     conn = self._get_connection()
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/host.py", line 515, in _get_connection
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     wrapped_conn = self._get_new_connection()
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/host.py", line 467, in _get_new_connection
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     wrapped_conn = self._connect(self._uri, self._read_only)
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/nova/virt/libvirt/host.py", line 321, in _connect
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     libvirt.openAuth, uri, auth, flags)
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/eventlet/tpool.py", line 144, in proxy_call
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     rv = execute(f, *args, **kwargs)
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/eventlet/tpool.py", line 125, in execute
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     six.reraise(c, e, tb)
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/eventlet/tpool.py", line 83, in tworker
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     rv = meth(*args, **kwargs)
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host   File "/usr/lib/python2.7/dist-packages/libvirt.py", line 105, in openAuth
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host     if ret is None:raise libvirtError('virConnectOpenAuth() failed')
2016-11-07 12:43:42.924 30047 ERROR nova.virt.libvirt.host libvirtError: Failed ...