How to process again documents already ingested

Hi all,
I would like to know if there is a way to process again documents already saved into the indices.
I noticed that my Logstash pipeline was not completed so now I know like to process a specific field.

in my documents, I have a field named build_type (generally with values like /OPS/service/build/username). I would like to extract a portion of that field for every documents.

thanks

If you want to run them through Logstash you will want to use the elasticsearch input and then run that through the rest of your config.

so, in my input section I must use elasticsearch plugin and the ingest them again?

The easiest way to do this is probably to use the reindex API with an ingest pipeline to make the change you are looking for.