由于6.0之后的版本，不再支持 document_type 这个选项了

Starting with Logstash 6.0, the document_type option is deprecated due to the removal of types in Logstash 6.0. It will be removed in the next major version of Logstash. If you are running Logstash 6.0 or later, you do not need to set document_type in your configuration because Logstash sets the type to doc by default.

所以为了lostash能区分不同目录发过来的日志，我们使用 tags属性

tags
A list of tags that the Beat includes in the tags field of each published event. Tags make it easy to select specific events in Kibana or apply conditional filtering in Logstash. These tags will be appended to the list of tags specified in the general configuration.