feat(lambda): read cloud.account.id from symlink in Lambda detector

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- `opentelemetry-sdk-extension-aws`: Read `cloud.account.id` from symlink created by the OTel Lambda Extension in the Lambda resource detector
+  ([#4183](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4183))
 - `opentelemetry-instrumentation-asgi`: Add exemplars for `http.server.request.duration` and `http.server.duration` metrics
   ([#3739](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3739))
 - `opentelemetry-instrumentation-wsgi`: Add exemplars for `http.server.request.duration` and `http.server.duration` metrics

sdk-extension/opentelemetry-sdk-extension-aws/CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Read `cloud.account.id` from symlink created by the OTel Lambda Extension in the Lambda resource detector
+  ([#4183](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4183))
+
 ## Version 2.1.0 (2024-12-24)
 
 - Make ec2 resource detector silent when loaded outside AWS

sdk-extension/opentelemetry-sdk-extension-aws/src/opentelemetry/sdk/extension/aws/resource/_lambda.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging
+import os
 from os import environ
 
 from opentelemetry.sdk.resources import Resource, ResourceDetector
@@ -24,6 +25,8 @@
 
 logger = logging.getLogger(__name__)
 
+_ACCOUNT_ID_SYMLINK_PATH = "/tmp/.otel-aws-account-id"
+
 
 class AwsLambdaResourceDetector(ResourceDetector):
     """Detects attribute values only available when the app is running on AWS
@@ -34,25 +37,31 @@ class AwsLambdaResourceDetector(ResourceDetector):
 
     def detect(self) -> "Resource":
         try:
-            return Resource(
-                {
-                    ResourceAttributes.CLOUD_PROVIDER: CloudProviderValues.AWS.value,
-                    ResourceAttributes.CLOUD_PLATFORM: CloudPlatformValues.AWS_LAMBDA.value,
-                    ResourceAttributes.CLOUD_REGION: environ["AWS_REGION"],
-                    ResourceAttributes.FAAS_NAME: environ[
-                        "AWS_LAMBDA_FUNCTION_NAME"
-                    ],
-                    ResourceAttributes.FAAS_VERSION: environ[
-                        "AWS_LAMBDA_FUNCTION_VERSION"
-                    ],
-                    ResourceAttributes.FAAS_INSTANCE: environ[
-                        "AWS_LAMBDA_LOG_STREAM_NAME"
-                    ],
-                    ResourceAttributes.FAAS_MAX_MEMORY: int(
-                        environ["AWS_LAMBDA_FUNCTION_MEMORY_SIZE"]
-                    ),
-                }
-            )
+            attributes = {
+                ResourceAttributes.CLOUD_PROVIDER: CloudProviderValues.AWS.value,
+                ResourceAttributes.CLOUD_PLATFORM: CloudPlatformValues.AWS_LAMBDA.value,
+                ResourceAttributes.CLOUD_REGION: environ["AWS_REGION"],
+                ResourceAttributes.FAAS_NAME: environ[
+                    "AWS_LAMBDA_FUNCTION_NAME"
+                ],
+                ResourceAttributes.FAAS_VERSION: environ[
+                    "AWS_LAMBDA_FUNCTION_VERSION"
+                ],
+                ResourceAttributes.FAAS_INSTANCE: environ[
+                    "AWS_LAMBDA_LOG_STREAM_NAME"
+                ],
+                ResourceAttributes.FAAS_MAX_MEMORY: int(
+                    environ["AWS_LAMBDA_FUNCTION_MEMORY_SIZE"]
+                ),
+            }
+
+            try:
+                account_id = os.readlink(_ACCOUNT_ID_SYMLINK_PATH)
+                attributes[ResourceAttributes.CLOUD_ACCOUNT_ID] = account_id
+            except OSError:
+                logger.debug("cloud.account.id not available via symlink")
+
+            return Resource(attributes)
         # pylint: disable=broad-except
         except Exception as exception:
             if self.raise_on_error:

sdk-extension/opentelemetry-sdk-extension-aws/tests/resource/test__lambda.py

@@ -12,12 +12,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 import unittest
 from collections import OrderedDict
 from unittest.mock import patch
 
+import pytest
+
 from opentelemetry.sdk.extension.aws.resource._lambda import (  # pylint: disable=no-name-in-module
     AwsLambdaResourceDetector,
+    _ACCOUNT_ID_SYMLINK_PATH,
 )
 from opentelemetry.semconv.resource import (
     CloudPlatformValues,
@@ -35,29 +39,68 @@
     ResourceAttributes.FAAS_MAX_MEMORY: 128,
 }
 
+MOCK_LAMBDA_ENV = {
+    "AWS_REGION": MockLambdaResourceAttributes[ResourceAttributes.CLOUD_REGION],
+    "AWS_LAMBDA_FUNCTION_NAME": MockLambdaResourceAttributes[ResourceAttributes.FAAS_NAME],
+    "AWS_LAMBDA_FUNCTION_VERSION": MockLambdaResourceAttributes[ResourceAttributes.FAAS_VERSION],
+    "AWS_LAMBDA_LOG_STREAM_NAME": MockLambdaResourceAttributes[ResourceAttributes.FAAS_INSTANCE],
+    "AWS_LAMBDA_FUNCTION_MEMORY_SIZE": f"{MockLambdaResourceAttributes[ResourceAttributes.FAAS_MAX_MEMORY]}",
+}
+
 
 class AwsLambdaResourceDetectorTest(unittest.TestCase):
     @patch.dict(
         "os.environ",
-        {
-            "AWS_REGION": MockLambdaResourceAttributes[
-                ResourceAttributes.CLOUD_REGION
-            ],
-            "AWS_LAMBDA_FUNCTION_NAME": MockLambdaResourceAttributes[
-                ResourceAttributes.FAAS_NAME
-            ],
-            "AWS_LAMBDA_FUNCTION_VERSION": MockLambdaResourceAttributes[
-                ResourceAttributes.FAAS_VERSION
-            ],
-            "AWS_LAMBDA_LOG_STREAM_NAME": MockLambdaResourceAttributes[
-                ResourceAttributes.FAAS_INSTANCE
-            ],
-            "AWS_LAMBDA_FUNCTION_MEMORY_SIZE": f"{MockLambdaResourceAttributes[ResourceAttributes.FAAS_MAX_MEMORY]}",
-        },
+        MOCK_LAMBDA_ENV,
         clear=True,
     )
     def test_simple_create(self):
         actual = AwsLambdaResourceDetector().detect()
         self.assertDictEqual(
             actual.attributes.copy(), OrderedDict(MockLambdaResourceAttributes)
         )
+
+
+@pytest.fixture
+def account_id_symlink(tmp_path):
+    """Create a symlink at a temporary path and patch the detector to use it."""
+    def _create(account_id):
+        symlink_path = tmp_path / ".otel-aws-account-id"
+        os.symlink(account_id, symlink_path)
+        return str(symlink_path)
+    return _create
+
+
+@patch.dict("os.environ", MOCK_LAMBDA_ENV, clear=True)
+def test_account_id_from_symlink(account_id_symlink):
+    """When the account ID symlink exists, cloud.account.id is set."""
+    symlink_path = account_id_symlink("123456789012")
+    with patch(
+        "opentelemetry.sdk.extension.aws.resource._lambda._ACCOUNT_ID_SYMLINK_PATH",
+        symlink_path,
+    ):
+        actual = AwsLambdaResourceDetector().detect()
+    assert actual.attributes[ResourceAttributes.CLOUD_ACCOUNT_ID] == "123456789012"
+
+
+@patch.dict("os.environ", MOCK_LAMBDA_ENV, clear=True)
+def test_account_id_missing_symlink():
+    """When the symlink does not exist, cloud.account.id is absent and no exception is raised."""
+    with patch(
+        "opentelemetry.sdk.extension.aws.resource._lambda._ACCOUNT_ID_SYMLINK_PATH",
+        "/tmp/.otel-aws-account-id-nonexistent",
+    ):
+        actual = AwsLambdaResourceDetector().detect()
+    assert ResourceAttributes.CLOUD_ACCOUNT_ID not in actual.attributes
+
+
+@patch.dict("os.environ", MOCK_LAMBDA_ENV, clear=True)
+def test_account_id_preserves_leading_zeros(account_id_symlink):
+    """Leading zeros in the account ID are preserved (treated as string)."""
+    symlink_path = account_id_symlink("000123456789")
+    with patch(
+        "opentelemetry.sdk.extension.aws.resource._lambda._ACCOUNT_ID_SYMLINK_PATH",
+        symlink_path,
+    ):
+        actual = AwsLambdaResourceDetector().detect()
+    assert actual.attributes[ResourceAttributes.CLOUD_ACCOUNT_ID] == "000123456789"