feat: add helper functions for extracting and restoring OTel context for context propagation

Signed-off-by: Casper Guldbech Nielsen <scni@novonordisk.com>

dapr_agents/agent/telemetry/otel.py

@@ -1,5 +1,5 @@
 from logging import Logger
-from typing import Union
+from typing import Any, Union
 
 import functools
 
@@ -16,6 +16,7 @@ from opentelemetry.trace import set_tracer_provider
 from opentelemetry.exporter.otlp.proto.http._log_exporter import OTLPLogExporter
 from opentelemetry.exporter.otlp.proto.http.metric_exporter import OTLPMetricExporter
 from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
+from opentelemetry.trace.propagation.tracecontext import TraceContextTextMapPropagator
 
 
 class DaprAgentsOTel:
@@ -174,12 +175,39 @@ def async_span_decorator(name):
         @functools.wraps(func)
         async def wrapper(self, *args, **kwargs):
             tracer = getattr(self, "_tracer", None)
-            if tracer:
-                with tracer.start_as_current_span(name):
-                    return await func(self, *args, **kwargs)
-            else:
+            if not tracer:
+                return await func(self, *args, **kwargs)
+
+            # Extract context from kwargs if available
+            otel_context = kwargs.pop("otel_context", None)
+            context = None
+
+            if otel_context:
+                # Restore parent context from carrier
+                from opentelemetry.trace.propagation.tracecontext import (
+                    TraceContextTextMapPropagator,
+                )
+
+                carrier = otel_context
+                context = TraceContextTextMapPropagator().extract(carrier=carrier)
+
+            # Start span with parent context if available
+            with tracer.start_as_current_span(name, context=context):
                 return await func(self, *args, **kwargs)
 
         return wrapper
 
     return decorator
+
+
+def extract_otel_context():
+    """Extract current OpenTelemetry context for cross-boundary propagation"""
+    carrier: dict[Any, Any] = {}
+    TraceContextTextMapPropagator().inject(carrier)
+    return carrier
+
+
+def restore_otel_context(carrier):
+    """Restore OpenTelemetry context from carrier"""
+    context = TraceContextTextMapPropagator().extract(carrier)
+    return context