code: def ensure_ceph_keyring(service, user=None, group=None,
                          relation='ceph', key=None):
      
      if not key:
          for rid in relation_ids(relation):
              for unit in related_units(rid):
                  key = relation_get('key', rid=rid, unit=unit)
                  if key:
                      break
  
      if not key:
          return False
  
      add_key(service=service, key=key)
      keyring = _keyring_path(service)
      if user and group:
          check_call(['chown', '%s.%s' % (user, group), keyring])
  
      return True
docs: Ensures a ceph keyring is created for a named service and optionally
      ensures user and group ownership.
  
      @returns boolean: Flag to indicate whether a key was successfully written
                        to disk based on either relation data or a supplied key