fix: update get_execution_role_arn from metadata file if present (aws#4388)

Author: jgoyani1

src/sagemaker/session.py

@@ -5412,14 +5412,19 @@ def get_caller_identity_arn(self):
                 domain_id = metadata.get("DomainId")
                 user_profile_name = metadata.get("UserProfileName")
                 space_name = metadata.get("SpaceName")
+                execution_role_arn = metadata.get("ExecutionRoleArn")
             try:
                 if domain_id is None:
                     instance_desc = self.sagemaker_client.describe_notebook_instance(
                         NotebookInstanceName=instance_name
                     )
                     return instance_desc["RoleArn"]
 
-                # In Space app, find execution role from DefaultSpaceSettings on domain level
+                # find execution role from the metadata file if present
+                if execution_role_arn is not None:
+                    return execution_role_arn
+
+                # In Shared Space app, find execution role from DefaultSpaceSettings on domain level
                 if space_name is not None:
                     domain_desc = self.sagemaker_client.describe_domain(DomainId=domain_id)
                     return domain_desc["DefaultSpaceSettings"]["ExecutionRole"]

tests/unit/test_session.py

@@ -698,6 +698,25 @@ def test_fallback_to_domain_if_role_unavailable_in_user_settings(boto_session):
     sess.sagemaker_client.describe_domain.assert_called_once_with(DomainId="d-kbnw5yk6tg8j")
 
 
+@patch(
+    "six.moves.builtins.open",
+    mock_open(
+        read_data='{"ResourceName": "SageMakerInstance", '
+        '"DomainId": "d-kbnw5yk6tg8j", '
+        '"ExecutionRoleArn": "arn:aws:iam::369233609183:role/service-role/SageMakerRole-20171129T072388", '
+        '"SpaceName": "space_name"}'
+    ),
+)
+@patch("os.path.exists", side_effect=mock_exists(NOTEBOOK_METADATA_FILE, True))
+def test_get_caller_identity_arn_from_metadata_file_for_space(boto_session):
+    sess = Session(boto_session)
+    expected_role = "arn:aws:iam::369233609183:role/service-role/SageMakerRole-20171129T072388"
+
+    actual = sess.get_caller_identity_arn()
+
+    assert actual == expected_role
+
+
 @patch(
     "six.moves.builtins.open",
     mock_open(