fix(llmobs): prevent duplicate tags in x-datadog-tags on injection - #9832
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patrickswedish wants to merge 1 commit into
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fix(llmobs): prevent duplicate tags in x-datadog-tags on injection#9832patrickswedish wants to merge 1 commit into
patrickswedish wants to merge 1 commit into
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When injecting LLMObs trace context into outbound carriers, handleLLMObsInjection previously appended propagated keys without checking whether existing x-datadog-tags already contained entries for those keys (for example, from standard trace tag propagation or upstream service headers). This resulted in duplicate entries such as multiple _dd.p.llmobs_ml_app values in x-datadog-tags. Use stripTagsetEntry before appending resolved LLMObs keys so existing entries are cleanly replaced without duplication. Fixes DataDog#9714
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What does this PR do?
Fixes a bug where injecting LLMObs trace context into outbound carrier headers (\x-datadog-tags) duplicated _dd.p.llmobs_ml_app\ (and potentially other LLMObs keys) when the carrier or trace context already contained those tags from upstream requests or standard trace tag propagation.
Motivation
When an inbound request carries _dd.p.llmobs_ml_app\ in \x-datadog-tags, standard trace propagation extracts it into _trace.tags. On an outbound request, _injectTags\ writes the existing tags into \x-datadog-tags, and subsequent LLMObs channel injection (\handleLLMObsInjection) unconditionally appended resolved LLMObs keys with a comma separator, resulting in duplicate entries like:
\
x-datadog-tags: _dd.p.tid=6a734d1a00000000,_dd.p.dm=-0,_dd.p.llmobs_ml_app=my-ml-app,_dd.p.llmobs_ml_app=my-ml-app
\\
By utilizing the existing \stripTagsetEntry\ helper before appending each resolved LLMObs key (\PROPAGATED_PARENT_ID_KEY, \PROPAGATED_ML_APP_KEY, \PROPAGATED_SESSION_ID_KEY, \PROPAGATED_SAMPLE_RATE_KEY, \PROPAGATED_SAMPLING_DECISION_KEY, \PROPAGATED_TRACE_ID_KEY), any pre-existing entry for that key is replaced cleanly without duplication.
Fixes #9714.
Additional Notes
Review checklist
o-changelog\ label attached