code: def write_conf(cluster, conf, overwrite):
      
      path = '/etc/ceph/{cluster}.conf'.format(cluster=cluster)
      tmp_file = tempfile.NamedTemporaryFile('w', dir='/etc/ceph', delete=False)
      err_msg = 'config file %s exists with different content; use --overwrite-conf to overwrite' % path
  
      if os.path.exists(path):
          with open(path, 'r') as f:
              old = f.read()
              if old != conf and not overwrite:
                  raise RuntimeError(err_msg)
          tmp_file.write(conf)
          tmp_file.close()
          shutil.move(tmp_file.name, path)
          os.chmod(path, 0o644)
          return
      if os.path.exists('/etc/ceph'):
          with open(path, 'w') as f:
              f.write(conf)
          os.chmod(path, 0o644)
      else:
          err_msg = '/etc/ceph/ does not exist - could not write config'
          raise RuntimeError(err_msg)
docs: write cluster configuration to /etc/ceph/{cluster}.conf