Description of problem:

RHOSP 16.2.5 + External Ceph 5.3 
During RHOSP 16.2.5 deployment, we tried to integrate with external ceph and facing " The CephFSID environment value does not match the stack  configuration value error."


Version-Release number of selected component (if applicable):
RHOSP 16.2.5 
Ceph 5.3


How reproducible:
1. Deploy RHOSP 16.2.5
2. Deployment external Ceph 5.3
3. Integrate RHOSP 16.2.5 with external Ceph 5.3
4. Update yaml (such as manila-cephfsnative-config.yaml) and deploy
or add new "cephfs" and deploy  

" The CephFSID environment value does not match the stack  configuration value error." shown.

It seems that yaml cannot be modified after integrating RHOSP 16.2.5 with external Ceph 5.3. 

Steps to Reproduce:
1.
2.
3.

Actual results:


Expected results:


Additional info:
We check the code related to " The CephFSID environment value does not match the stack  configuration value error."
~~~
  env_ceph_fsid = environment.get('parameter_defaults',
                                    {}).get('CephClusterFSID', False)
    stack_ceph_fsid = stack.environment().get('parameter_defaults',
                                              {}).get('CephClusterFSID', False)

    if bool(env_ceph_fsid) and env_ceph_fsid != stack_ceph_fsid:
        raise exceptions.InvalidConfiguration('The CephFSID environment value '
                                              ' ({}) does not match the stack '
                                              ' configuration value ({}).'
                                              ' Ensure the CephClusterFSID '
                                              ' param is properly configured '
                                              ' in the storage environment '
                                              ' files.'
                                              .format(env_ceph_fsid,
                                                      stack_ceph_fsid))
~~~

I am thinking that if CephFSID will be generated each time with new one during each integrating. 
Please help to check

Regards
Sam