You can use the Logstask and install the log agent in the Elasticsearch.

Also you can configure the agent yaml file with the integration of MongoDB.

When you are indexing your elasticsearch system for the full text search it is sending logs and it is directly connected to the MongoDB.

In this case field mapping is important and I hope you to use the recommended fields for the Elasticsearch.

While syncing some errors are coming from the date format. I can help you if you want more. Thanks.