Add trace_propagation_meta helper to hub to generate meta tags

Author: sl0thentr0py

sentry_sdk/hub.py

@@ -717,6 +717,19 @@ def iter_trace_propagation_headers(self, span=None):
         for header in span.iter_headers():
             yield header
 
+    def trace_propagation_meta(self, span=None):
+        # type: (Optional[Span]) -> str
+        """
+        Return meta tags which should be injected into the HTML template
+        to allow propagation of trace data.
+        """
+        meta = ""
+
+        for name, content in self.iter_trace_propagation_headers(span):
+            meta += '<meta name="%s" content="%s">' % (name, content)
+
+        return meta
+
 
 GLOBAL_HUB = Hub()
 _local.set(GLOBAL_HUB)

sentry_sdk/tracing_utils.py

@@ -477,7 +477,6 @@ def populate_from_transaction(cls, transaction):
         Populate fresh baggage entry with sentry_items and make it immutable
         if this is the head SDK which originates traces.
         """
-
         hub = transaction.hub or sentry_sdk.Hub.current
         client = hub.client
         sentry_items = {}  # type: Dict[str, str]
@@ -511,6 +510,12 @@ def populate_from_transaction(cls, transaction):
         if transaction.sample_rate is not None:
             sentry_items["sample_rate"] = str(transaction.sample_rate)
 
+        # there's an existing baggage but it was mutable,
+        # which is why we are creating this new baggage.
+        # However, if by chance the user put some sentry items in there, give them precedence.
+        if transaction._baggage and transaction._baggage.sentry_items:
+            sentry_items.update(transaction._baggage.sentry_items)
+
         return Baggage(sentry_items, mutable=False)
 
     def freeze(self):