feat(llmobs): user processor can add metadata to span

Author: matthgt

ddtrace/llmobs/_llmobs.py

@@ -203,6 +203,7 @@ def span_processor(span: LLMObsSpan) -> Optional[LLMObsSpan]:
 
     input: List[Message] = field(default_factory=list)
     output: List[Message] = field(default_factory=list)
+    metadata: Dict[str, Any] = field(default_factory=dict)
     _tags: Dict[str, str] = field(default_factory=dict)
 
     def get_tag(self, key: str) -> Optional[str]:
@@ -409,6 +410,8 @@ def _llmobs_span_event(self, span: Span) -> Optional[LLMObsSpanEvent]:
                 meta["output"]["messages"] = llmobs_span.output
             elif output_type == "value":
                 meta["output"]["value"] = llmobs_span.output[0].get("content", "")
+        if llmobs_span.metadata:
+            meta["metadata"].update(llmobs_span.metadata)
 
         if not meta["input"]:
             meta.pop("input")

releasenotes/notes/llmobs-allow-users-to-add-metadata-a6b08373b8131609.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    LLMObs: This update introduces the ability for users to add custom metadata to LLMObs spans 
+    by setting a `metadata` attribute on the `LLMObsSpan` object passed to their registered 
+    span processors.