[BUG] OTLP-ingested traces tagged ingestion_reason:manual when client did not force-keep

[sdwa0]

Agent version

7.79.0

Bug Report

The Datadog backend surfaces traces ingested via Datadog agent's OTLP ingest as ingestion_reason:manual even when the client never force-kept them.

This might be a result of these lines of code in the OTLP receiver that stamp _dd.p.dm = -4 (manual) on any trace whose spans carry a sampling.priority attribute, regardless of its value.

		if p, ok := prioritiesByID[k]; ok {
			// a manual decision has been made by the user
			samplingPriorty = p
			decisionMaker = "-4"
		} else {

Reproduction Steps

No response

Agent configuration

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Operating System

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Other environment details

No response

[jade-guiton-dd]

Hello 👋 Could you clarify what you mean by "even when the client never force-kept them"? Specifically, what value of sampling.priority are you setting on your spans?

To my knowledge, the implementation of sampling.priority in the Datadog Agent's OTLP ingest is very basic: any value below 1 should be forcefully dropped, and any value at or above 1 should be forcefully kept. Both situations correspond to ingestion_reason:manual.