Description of problem:
I deployed the overcloud with external Ceph with one user, I tried to change the Ceph user I was using on the overcloud. After updating the overcloud, the cephx keyring of the Ceph user the key change doesn't affect the key that is was set in libvirt's secret on the Nova compute nodes. 

Version-Release number of selected component (if applicable):
openstack-tripleo-heat-templates-2.0.0-18.el7ost.noarch
openstack-tripleo-common-2.0.0-6.el7ost.noarch
openstack-tripleo-image-elements-0.9.9-6.el7ost.noarch
python-tripleoclient-2.0.0-1.0.6.el7ost.noarch
openstack-tripleo-heat-templates-kilo-2.0.0-18.el7ost.noarch
openstack-tripleo-heat-templates-liberty-2.0.0-18.el7ost.noarch
openstack-tripleo-puppet-elements-2.0.0-3.el7ost.noarch
openstack-tripleo-0.0.8-0.2.d81bd6dgit.el7ost.noarch


How reproducible:
100%

Steps to Reproduce:
1. deploy overcloud with 1 keyring 
2. update the details of the Ceph user in the environment file
3. launch an instance

Actual results:
Nova fails to launch instances due to bad configuration & lack of permissions on the Ceph storage


Expected results:
The keyring that is related to Libvirt's secret has changed during the update

Additional info: