Update legacy Cloud Trace exporter attribute and span limits to match backend

opentelemetry-exporter-gcp-trace/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Update span and attribute limits to match Cloud Trace backend
+
 ## Version 1.14.0
 
 Released 2026-08-03

opentelemetry-exporter-gcp-trace/src/opentelemetry/exporter/cloud_trace/__init__.py

@@ -137,12 +137,12 @@
 
 
 MAX_NUM_LINKS = 128
-MAX_NUM_EVENTS = 32
-MAX_EVENT_ATTRS = 4
-MAX_LINK_ATTRS = 32
-MAX_SPAN_ATTRS = 32
-MAX_ATTR_KEY_BYTES = 128
-MAX_ATTR_VAL_BYTES = 16 * 1024  # 16 kilobytes
+MAX_NUM_EVENTS = 256
+MAX_EVENT_ATTRS = 1024
+MAX_LINK_ATTRS = 1024
+MAX_SPAN_ATTRS = 1024
+MAX_ATTR_KEY_BYTES = 512
+MAX_ATTR_VAL_BYTES = 64 * 1024  # 64 kilobytes
 
 
 def _create_default_client() -> TraceServiceClient:
@@ -260,7 +260,7 @@ def _translate_to_cloud_trace(
                 trace_types.Span(
                     name=span_name,
                     span_id=span_id,
-                    display_name=_get_truncatable_str_object(span.name, 128),
+                    display_name=_get_truncatable_str_object(span.name, 1024),
                     start_time=start_time,
                     end_time=end_time,
                     parent_span_id=parent_id,
@@ -400,7 +400,7 @@ def _extract_events(
             trace_types.Span.TimeEvent(
                 time=_get_time_from_ns(event.timestamp),
                 annotation=trace_types.Span.TimeEvent.Annotation(
-                    description=_get_truncatable_str_object(event.name, 256),
+                    description=_get_truncatable_str_object(event.name, 1024),
                     attributes=_extract_attributes(
                         event.attributes, MAX_EVENT_ATTRS
                     ),

opentelemetry-exporter-gcp-trace/tests/test_cloud_trace_exporter.py

@@ -102,8 +102,12 @@ def setUpClass(cls):
         cls.example_span_id = "95bb5edabd45950f"
         cls.example_time_in_ns = 1589919268850900051
         cls.example_time_stamp = _get_time_from_ns(cls.example_time_in_ns)
-        cls.str_20kb = "a" * 20 * 1024
-        cls.str_16kb = "a" * 16 * 1024
+        cls.str_70kb = "a" * 70 * 1024
+        cls.str_64kb = "a" * 64 * 1024
+        cls.str_1100 = "a" * 1100
+        cls.str_1024 = "a" * 1024
+        cls.str_600 = "a" * 600
+        cls.str_512 = "a" * 512
         cls.str_300 = "a" * 300
         cls.str_256 = "a" * 256
         cls.str_128 = "a" * 128
@@ -338,22 +342,22 @@ def test_agent_attribute_priority(self):
     def test_attribute_value_truncation(self):
         # shouldn't truncate
         self.assertEqual(
-            _format_attribute_value(self.str_300),
+            _format_attribute_value(self.str_600),
             AttributeValue(
                 string_value=TruncatableString(
-                    value=self.str_300,
+                    value=self.str_600,
                     truncated_byte_count=0,
                 )
             ),
         )
 
         # huge string should truncate
         self.assertEqual(
-            _format_attribute_value(self.str_20kb),
+            _format_attribute_value(self.str_70kb),
             AttributeValue(
                 string_value=TruncatableString(
-                    value=self.str_16kb,
-                    truncated_byte_count=(20 - 16) * 1024,
+                    value=self.str_64kb,
+                    truncated_byte_count=(70 - 64) * 1024,
                 )
             ),
         )
@@ -395,11 +399,11 @@ def test_list_attribute_value(self):
     def test_attribute_key_truncation(self):
         self.assertEqual(
             _extract_attributes(
-                {self.str_300: "attr_value"}, num_attrs_limit=4
+                {self.str_600: "attr_value"}, num_attrs_limit=4
             ),
             ProtoSpan.Attributes(
                 attribute_map={
-                    self.str_128: AttributeValue(
+                    self.str_512: AttributeValue(
                         string_value=TruncatableString(
                             value="attr_value", truncated_byte_count=0
                         )
@@ -504,7 +508,9 @@ def test_extract_multiple_events(self):
 
     def test_event_name_truncation(self):
         event1 = Event(
-            name=self.str_300, attributes={}, timestamp=self.example_time_in_ns
+            name=self.str_1100,
+            attributes={},
+            timestamp=self.example_time_in_ns,
         )
         self.assertEqual(
             _extract_events([event1]),
@@ -514,8 +520,8 @@ def test_event_name_truncation(self):
                         "time": self.example_time_stamp,
                         "annotation": {
                             "description": TruncatableString(
-                                value=self.str_256,
-                                truncated_byte_count=300 - 256,
+                                value=self.str_1024,
+                                truncated_byte_count=1100 - 1024,
                             ),
                             "attributes": {},
                         },
@@ -780,3 +786,23 @@ def test_extract_span_kind(self):
         self.assertEqual(
             _extract_span_kind(-1), ProtoSpan.SpanKind.SPAN_KIND_UNSPECIFIED
         )
+
+    def test_span_name_truncation(self):
+        exporter = CloudTraceSpanExporter(self.project_id)
+        span_data = Span(
+            name=self.str_1100,
+            context=SpanContext(
+                trace_id=int(self.example_trace_id, 16),
+                span_id=int(self.example_span_id, 16),
+                is_remote=False,
+            ),
+        )
+        # pylint: disable=protected-access
+        translated_spans = exporter._translate_to_cloud_trace([span_data])
+        self.assertEqual(
+            translated_spans[0].display_name,
+            TruncatableString(
+                value=self.str_1024,
+                truncated_byte_count=1100 - 1024,
+            ),
+        )