Logstash default document_type inconsistent with types removal recommendation

[hackery]

I asked this previously on the forum but it didn't seem to draw any attention.

The advice in the doctype deprecation notes is to use a document type of _doc in 6.x to prepare for type removal. However the Logstash Elasticsearch output plugin defaults to doc.

At this point we should be able to omit the document_type parameter (which flags a deprecation warning!) and not require that configuration change between 6.x and 7.x.

[pemontto]

Same as #796

This just stung us hard going to ES7. It seems this plugin will use doc with ES6 and _doc with ES7 😞. Not even a mention in the breaking changes - https://www.elastic.co/guide/en/logstash/7.x/breaking-7.0.html

Cue tonnes of error messages:

Rejecting mapping update to [x] as the final mapping would have more than 1 type: [_doc, doc]

[davidhowell-tx]

Glad to hear this is only an issue when you're on ES6. I was upgrading my index templates and came across this issue. Having to pick between setting my index templates back the way they were and seeing a deprecation warning, or setting all of my Logstash outputs to document_type => "_doc" and seeing a deprecation warning.

[kares]

has been resolved in #994