docs: def cluster_join(username, hostname):
      '''
      Join a Riak cluster
  
      .. versionchanged:: 2015.8.0
  
      CLI Example:
  
      .. code-block:: bash
  
          salt '*' riak.cluster_join <user> <host>
  
      username - The riak username to join the cluster
      hostname - The riak hostname you are connecting to
      '''
      ret = {'comment': '', 'success': False}
  
      cmd = __execute_cmd(
          'riak-admin', 'cluster join {0}@{1}'.format(username, hostname)
      )
  
      if cmd['retcode'] != 0:
          ret['comment'] = cmd['stdout']
      else:
          ret['comment'] = cmd['stdout']
          ret['success'] = True
  
      return ret