[root@kolla ceph-ansible]# ansible-playbook site.yml
ERROR! the role 'ceph-defaults' was not found in /root/ceph-ansible/roles:/root/ceph-ansible/roles:/root/ceph-ansible

The error appears to have been in '/root/ceph-ansible/site.yml': line 45, column 7, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  roles:
    - ceph-defaults
      ^ here