Add custom ADOT UserAgent for OTLP Spans Exporter (#554)

*Description of changes:*

- Added custom User-Agent header to AWS OTLP span exporter that adds
"GenAI" when agent observability is enabled.

<img width="1159" height="195" alt="image"
src="https://github.com/user-attachments/assets/65a65bfc-4ba3-4555-8c07-4c05335f73cc"
/>

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

Author: liustve

CHANGELOG.md

@@ -11,6 +11,8 @@ For any change that affects end users of this package, please add an entry under
 If your change does not need a CHANGELOG entry, add the "skip changelog" label to your PR.
 
 ## Unreleased
+- Add custom ADOT UserAgent for OTLP Spans Exporter
+  ([#554](https://github.com/aws-observability/aws-otel-python-instrumentation/pull/554))
 - Disable django instrumentation if DJANGO_SETTINGS_MODULE is not set
   ([#549](https://github.com/aws-observability/aws-otel-python-instrumentation/pull/549))
 - [PATCH] Add safety check for bedrock ConverseStream responses

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/otlp/aws/common/_aws_http_headers.py

@@ -0,0 +1,18 @@
+# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+from amazon.opentelemetry.distro._utils import is_agent_observability_enabled
+from amazon.opentelemetry.distro.version import __version__
+
+
+def build_user_agent() -> str:
+    user_agent = f"ADOT-OTLP-Exporter-Python/{__version__}"
+
+    if is_agent_observability_enabled():
+        user_agent = f"ADOT-GenAI-OTLP-Exporter-Python/{__version__}"
+    return user_agent
+
+
+_OTLP_AWS_HTTP_HEADERS = {
+    "User-Agent": build_user_agent(),
+}

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/otlp/aws/traces/otlp_aws_span_exporter.py

@@ -7,6 +7,7 @@
 from botocore.session import Session
 
 from amazon.opentelemetry.distro._utils import is_agent_observability_enabled
+from amazon.opentelemetry.distro.exporter.otlp.aws.common._aws_http_headers import _OTLP_AWS_HTTP_HEADERS
 from amazon.opentelemetry.distro.exporter.otlp.aws.common.aws_auth_session import AwsAuthSession
 from amazon.opentelemetry.distro.llo_handler import LLOHandler
 from opentelemetry._logs import get_logger_provider
@@ -56,6 +57,7 @@ def __init__(
             compression,
             session=AwsAuthSession(session=session, aws_region=self._aws_region, service="xray"),
         )
+        self._session.headers.update(_OTLP_AWS_HTTP_HEADERS)
 
     def _ensure_llo_handler(self):
         """Lazily initialize LLO handler when needed to avoid initialization order issues"""

aws-opentelemetry-distro/tests/amazon/opentelemetry/distro/exporter/otlp/aws/traces/test_otlp_aws_span_exporter.py

@@ -5,6 +5,7 @@
 from unittest.mock import MagicMock, patch
 
 from amazon.opentelemetry.distro._utils import get_aws_session
+from amazon.opentelemetry.distro.exporter.otlp.aws.common._aws_http_headers import _OTLP_AWS_HTTP_HEADERS
 from amazon.opentelemetry.distro.exporter.otlp.aws.traces.otlp_aws_span_exporter import OTLPAwsSpanExporter
 from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
 from opentelemetry.sdk._logs import LoggerProvider
@@ -35,6 +36,20 @@ def test_init_without_logger_provider(self):
         self.assertEqual(exporter._aws_region, "us-west-2")
         self.assertIsNone(exporter._llo_handler)
 
+    def test_aws_headers_applied(self):
+        endpoint = "https://xray.us-east-1.amazonaws.com/v1/traces"
+        custom_headers = {"X-Custom-Header": "custom-value"}
+
+        exporter = OTLPAwsSpanExporter(
+            session=get_aws_session(), aws_region="us-east-1", endpoint=endpoint, headers=custom_headers
+        )
+
+        for key in _OTLP_AWS_HTTP_HEADERS.keys():
+            self.assertIn(key, exporter._session.headers)
+
+        self.assertEqual(exporter._session.headers["X-Custom-Header"], "custom-value")
+        self.assertIn("User-Agent", exporter._session.headers)
+
     @patch("amazon.opentelemetry.distro.exporter.otlp.aws.traces.otlp_aws_span_exporter.is_agent_observability_enabled")
     def test_ensure_llo_handler_when_disabled(self, mock_is_enabled):
         # Test _ensure_llo_handler when agent observability is disabled