Description of problem:

When file storage driver and NFS share is used in Gnocchi, overcloud deploy fails at step 2.

2020-06-01 12:55:41,020 p=512345 u=mistral |  TASK [Wait for containers to start for step 2 using paunch] ********************
2020-06-01 12:55:41,020 p=512345 u=mistral |  task path: /var/lib/mistral/overcloud/common_deploy_steps_tasks.yaml:174
2020-06-01 12:55:41,021 p=512345 u=mistral |  Friday 01 June 2020  11:55:41 +0900 (0:00:01.244)       0:22:28.047 *********** 
...
2020-06-01 12:59:26,028 p=512345 u=mistral |  fatal: [controller-1]: FAILED! => {"ansible_job_id": "26087583737.58046", "attempts": 71, "changed": false, "finished": 1, "msg": "Paunch failed with config_id tripleo_step2", "rc": 126, ...
2020-06-01 12:59:26,204 p=512345 u=mistral |  fatal: [controller-2]: FAILED! => {"ansible_job_id": "957944797099.57990", "attempts": 71, "changed": false, "finished": 1, "msg": "Paunch failed with config_id tripleo_step2", "rc": 126, 
2020-06-01 13:03:24,083 p=512345 u=mistral |  fatal: [controller-0]: FAILED! => {"ansible_job_id": "857975676694.58634", "attempts": 145, "changed": false, "finished": 1, "msg": "Paunch failed with config_id tripleo_step2", "rc": 126 ...
2020-06-01 13:03:24,095 p=512345 u=mistral |  NO MORE HOSTS LEFT *************************************************************
2020-06-01 13:03:24,096 p=512345 u=mistral |  PLAY RECAP *********************************************************************
2020-06-01 13:03:24,096 p=512345 u=mistral |  undercloud                 : ok=19   changed=8    unreachable=0    failed=0    skipped=19   rescued=0    ignored=0   
2020-06-01 13:03:24,096 p=512345 u=mistral |  compute-0                  : ok=215  changed=124  unreachable=0    failed=0    skipped=89   rescued=0    ignored=0   
2020-06-01 13:03:24,097 p=512345 u=mistral |  compute-1                  : ok=211  changed=124  unreachable=0    failed=0    skipped=89   rescued=0    ignored=0   
2020-06-01 13:03:24,097 p=512345 u=mistral |  controller-0               : ok=277  changed=167  unreachable=0    failed=1    skipped=116  rescued=0    ignored=0   
2020-06-01 13:03:24,097 p=512345 u=mistral |  controller-1               : ok=269  changed=167  unreachable=0    failed=1    skipped=116  rescued=0    ignored=0   
2020-06-01 13:03:24,097 p=512345 u=mistral |  controller-2               : ok=269  changed=167  unreachable=0    failed=1    skipped=116  rescued=0    ignored=0   
2020-06-01 13:03:24,097 p=512345 u=mistral |  Friday 01 June 2020  16:03:24 +0900 (0:07:43.076)       0:30:11.123 *********** 
2020-06-01 13:03:24,098 p=512345 u=mistral |  =============================================================================== 

According to the paunch.log in controller nodes, we can identify the error with gnocci_init_lib
because it tried to relabel /var/lib/gnocchi, but failed because nfs shared doesn't support that operation.

paunch.log
~~~
2020-06-01 11:55:44.268 58639 ERROR paunch [  ] Error running ['podman', 'run', '--name', 'gnocchi_init_lib', '--label', 'config_id=tripleo_step2', '--label', 'container_name=gnocchi_init_lib', '--label', 'managed_by=tripleo-Controller', '--label', 'config_data={"command": ["/bin/bash", "-c", "chown -R gnocchi:gnocchi /var/lib/gnocchi"], "image": "192.168.24.1:8787/rhosp-rhel8/openstack-gnocchi-api:16.0-96", "net": "none", "user": "root", "volumes": ["/var/lib/gnocchi:/var/lib/gnocchi:shared,z"]}', '--conmon-pidfile=/var/run/gnocchi_init_lib.pid', '--detach=true', '--log-driver', 'k8s-file', '--log-opt', 'path=/var/log/containers/stdouts/gnocchi_init_lib.log', '--net=none', '--user=root', '--volume=/var/lib/gnocchi:/var/lib/gnocchi:shared,z', '--cpuset-cpus=0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15', '192.168.24.1:8787/rhosp-rhel8/openstack-gnocchi-api:16.0-96', '/bin/bash', '-c', 'chown -R gnocchi:gnocchi /var/lib/gnocchi']. [126]

2020-06-01 11:55:44.269 58639 ERROR paunch [  ] stdout: 
2020-06-01 11:55:44.269 58639 ERROR paunch [  ] stderr: Error: relabel failed "/var/lib/gnocchi": operation not supported
~~~

We have the fix for similar issue in nova[1] and glance[2], and we need the same for gnocchi
to resolve the error.
 [1] https://github.com/openstack/tripleo-heat-templates/commit/b56c521e01d0a4b42f44f2d9d03f524a4dc60475
 [2] https://github.com/openstack/tripleo-heat-templates/commit/aa1f4bf62156fa5e72b8171702acf3db755a67d8

Note that currently tripleo doesn't support file driver + nfs share in gnocchi.
To achieve this deployment, nfs share should be configured additionally in ExtraConfigPre.


Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. Deploy overcloud with nfs driver + nfs share for gnocchi

Actual results:
overcloud deploy fails at step 2

Expected results:
overcloud deploy completes without any failures 


Additional info: