Logs already in Elasticsearch, how to parse?

Elastic Stack Elasticsearch
1

Hello,

Currently upgraded to 7.2 i am starting to use ELK, and trying to get efficiently.
I didn't notice fast enough that I could use Grok with filebeats, and send to logstash which sends afterwards to Elasticsearch.

So now, some logs (~50Gb) are actually already stored in elasticsearch and I need to parse the message tags values since I didn't do it beforehand.
Is there any way to parse the data that are already on it, so I could make visualizations efficiently afterwards ?

I swear, next time i'll use Grok patterns directly from filebeat to logstash beforehand !

Thanks

2

You should be able to use the reindex api together with an ingest pipeline.