From 01f4ceb2f7feafd440ecf2da33f80af77224d204 Mon Sep 17 00:00:00 2001
From: Neel Shah <neel.shah@sentry.io>
Date: Fri, 2 May 2025 14:40:16 +0200
Subject: [PATCH 1/2] Add logger.debug for sampler decisions for root spans

---
 sentry_sdk/opentelemetry/sampler.py | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/sentry_sdk/opentelemetry/sampler.py b/sentry_sdk/opentelemetry/sampler.py
index fb68b644b5..ab3defe3de 100644
--- a/sentry_sdk/opentelemetry/sampler.py
+++ b/sentry_sdk/opentelemetry/sampler.py
@@ -234,7 +234,7 @@ def should_sample(
                     )
             else:
                 logger.debug(
-                    f"[Tracing] Ignoring sampled param for non-root span {name}"
+                    f"[Tracing.Sampler] Ignoring sampled param for non-root span {name}"
                 )
 
         # Check if there is a traces_sampler
@@ -264,7 +264,7 @@ def should_sample(
         # If the sample rate is invalid, drop the span
         if not is_valid_sample_rate(sample_rate, source=self.__class__.__name__):
             logger.warning(
-                f"[Tracing] Discarding {name} because of invalid sample rate."
+                f"[Tracing.Sampler] Discarding {name} because of invalid sample rate."
             )
             return dropped_result(parent_span_context, attributes)
 
@@ -279,6 +279,11 @@ def should_sample(
         sampled = sample_rand < Decimal.from_float(sample_rate)
 
         if sampled:
+            if is_root_span:
+                logger.debug(
+                    f"[Tracing.Sampler] Sampled #{name} with sample_rate: {sample_rate} and sample_rand: {sample_rand}"
+                )
+
             return sampled_result(
                 parent_span_context,
                 attributes,
@@ -286,6 +291,11 @@ def should_sample(
                 sample_rand=None if sample_rand == parent_sample_rand else sample_rand,
             )
         else:
+            if is_root_span:
+                logger.debug(
+                    f"[Tracing.Sampler] Dropped #{name} with sample_rate: {sample_rate} and sample_rand: {sample_rand}"
+                )
+
             return dropped_result(
                 parent_span_context,
                 attributes,

From 454cafd7d9f32fd8885417cd976421a5632166ef Mon Sep 17 00:00:00 2001
From: Neel Shah <neel.shah@sentry.io>
Date: Fri, 2 May 2025 15:26:15 +0200
Subject: [PATCH 2/2] Respect parent_sampled decision in propagation_context
 sentry-trace header

---
 sentry_sdk/scope.py         |  6 +-----
 sentry_sdk/tracing_utils.py | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/sentry_sdk/scope.py b/sentry_sdk/scope.py
index 975ac6fe04..dec8e70e22 100644
--- a/sentry_sdk/scope.py
+++ b/sentry_sdk/scope.py
@@ -505,11 +505,7 @@ def get_traceparent(self, *args, **kwargs):
 
         # If this scope has a propagation context, return traceparent from there
         if self._propagation_context is not None:
-            traceparent = "%s-%s" % (
-                self._propagation_context.trace_id,
-                self._propagation_context.span_id,
-            )
-            return traceparent
+            return self._propagation_context.to_traceparent()
 
         # Fall back to isolation scope's traceparent. It always has one
         return self.get_isolation_scope().get_traceparent()
diff --git a/sentry_sdk/tracing_utils.py b/sentry_sdk/tracing_utils.py
index a323b84199..20b88f1e32 100644
--- a/sentry_sdk/tracing_utils.py
+++ b/sentry_sdk/tracing_utils.py
@@ -432,6 +432,21 @@ def span_id(self, value):
         # type: (str) -> None
         self._span_id = value
 
+    def to_traceparent(self):
+        # type: () -> str
+        if self.parent_sampled is True:
+            sampled = "1"
+        elif self.parent_sampled is False:
+            sampled = "0"
+        else:
+            sampled = None
+
+        traceparent = "%s-%s" % (self.trace_id, self.span_id)
+        if sampled is not None:
+            traceparent += "-%s" % (sampled,)
+
+        return traceparent
+
     def update(self, other_dict):
         # type: (Dict[str, Any]) -> None
         """