[exporter/elasticsearch] Add OTel mapping mode for traces

[carsonip]

Description:

Add OTel mapping mode for traces.

OTel mapping mode is a new mapping mode described in https://github.com/open-telemetry/opentelemetry-collector-contrib/tree/main/exporter/elasticsearchexporter#elasticsearch-document-mapping

Update logs and metrics OTel mapping mode to always emit "scope" and zero int, but not emit empty strings for known fields.

Breaking change to remove trace_flags from logs.

Link to tracking Issue:
Fixes #34588 #34590

Testing:
Added exporter tests

Documentation:

[lahsivjar]

nit: pcommon.Map#Get could get expensive with more attributes. Though I don't think we would have a huge number of keys for it to be a conecern but it is not helping with readability of the code either. Also, I am not a fan of these util functions. How about:

	attributeMap.RemoveIf(func(k string, v pcommon.Value) bool {
		// just a few keys in datastream keys
		if slices.Contains(datastreamKeys, k) {
			// Add attribute will not add empty values
			document.AddAttribute(k, v)
			return true
		}
		return false
	})

[carsonip]

I agree that it is not great. It was designed as such as we need to call addDataStreamAttributes for record level attributes, and stripDataStreamAttributes for all resource, scope, and record level attributes. Splitting them into 2 functions makes it easier to understand. Performance would have been fine if attributes Get was O(1), but the current implementation isn't.

Would you still prefer implementing it inline for all 3 kinds of attributes?

[lahsivjar]

Would you still prefer implementing it inline for all 3 kinds of attributes?

I think the function call is simple enough to inline and would also be better for readability. So, my vote is to inline.

[carsonip]

done, looking much cleaner now.

[lahsivjar]

Gave a quick look, a couple of comments for code readability. Will give another look once the PR is updated with the changes after the dependent PR is merged.

[lahsivjar]

LGTM! A non-blocker question about trace flags.

Separate from the PR, we need to refactor the objmodel and model as it is getting harder to reason about these.

[atoulme]

same feedback as on the metrics PR, any chance you can add more to this note to explain what this change is about?

[carsonip]

OTel mapping mode, aka OTel native mapping mode, is a new mapping mode that is actively under development, where it maps to a model that's very close to the actual OTel data model, unlike ECS mode where a lot of translations are done in elasticsearchexporter. See elasticsearchexporter docs for details. We don't have public docs about mapping that we can point to yet, as it is all under active development. It requires Elasticsearch native support to magically keep the existing UIs working.

There's an initial implementation for logs (done in #33290) as you may have noticed, and here comes the traces (this PR) and metrics (#34248) counterparts.

[atoulme]

this is a difference of treatment compared to the resource level. Don't you want to set this always even if zero?

[carsonip]

Nice catch. I think it was initially implemented in this manner in a previous PR for efficiency: #33290 . Also, scope is skipped entirely if there is nothing interesting, unlike resource.

But I'll get back to the team and see if there is any implication on data correctness.

[carsonip]

Updated the PR to keep the handling consistent