_id doesn't make it through to elasticSearch

[Grokling]

I have Logstash consuming CouchDB's _changes api, and outputting to ElasticSearch.

The _id field from the original CouchDB document is lost on it's way into ElasticSearch. Underscore fields are ES meta fields. ES assigns a new _id, and the original is lost.

My use case is that I should have a set of results coming back from ES, then my client can subscribe (by _id) to the one they want to replicate (from couchDB). Without the _id, this scenario falls flat.

There is a keep_revision flag https://www.elastic.co/guide/en/logstash/current/plugins-inputs-couchdb_changes.html#plugins-inputs-couchdb_changes-keep_revision

Could we have either a keep_id flag (similar to keep_revision), or a means to map an incoming '_id' to an outgoing 'id' property in Logstash in order to avoid the underscore prefix overlap and allow ES to retain the key detail of the document?

[untergeek]

The document id is not passed because you need to tell the elasticsearch plugin which field to pass. See: https://www.elastic.co/guide/en/logstash/current/plugins-outputs-elasticsearch.html#plugins-outputs-elasticsearch-document_id

The document id from couchdb is automatically put in the [@metadata][_id] field. Your elasticsearch output needs to include: document_id => %{[@metadata][_id]} (though perhaps the %{} wrapper is unnecessary).

[Grokling]

Thanks for the speedy reply - sadly I'm not winning yet.
I've tried these all, but each is invalid.
document_id => %{[@metadata][_id]}
document_id => {[@metadata][_id]}
document_id => [@metadata][_id]
document_id => @metadata._id

I can get document_id => "@metadata._id" to work, but obviously that's not very useful!

The full config is:
elasticsearch { host => "elasticsearch" port => "9200" protocol => "http" index => "hx" document_id => %{[@metadata][_id]} }

[klingsor83]

I use document_id => "%{[@metadata][_id]}" and it works correctly. Maybe you only need to put the quotes...

[Grokling]

klingsor83 - that did it. Thanks very much.

[untergeek]

Sorry for omitting the "". I was trying to comment via my phone, and it's hard to get all of that punctuation in there and get a good overview of what you're writing.