Container is unable to start and stays unhealthy in controllers.

Issue

• Nova containers can't start and stay unhealthy due to a permission denied error

ERROR nova IOError: [Errno 13] Permission denied: '/etc/nova/policy.json'

• Checking the state of the containers we can see the following

[root@overcloud-controller-0 ~]# docker ps |grep -i nova
39408ad0bb23 hostname.com:5000/containers-nova-api:latest "dumb-init --singl..." 2 years ago Up 38 hours (unhealthy) nova_metadata
8b7d881047a3 hostname.com:5000/containers-nova-api:latest "dumb-init --singl..." 2 years ago Up 40 hours (unhealthy) nova_api
4dea86b09f2a hostname.com:5000/containers-nova-scheduler:latest "kolla_start" 2 years ago Up 45 hours (unhealthy) nova_scheduler