fix(bigquery): BigFrames notebook execution when using a service account with oauth (#1232)

Co-authored-by: Colin Rogers <[email protected]>

Author: jaime-spencer-oxb

dbt-bigquery/.changes/unreleased/Fixes-20250901-100053.yaml

@@ -0,0 +1,6 @@
+kind: Fixes
+body: BigFrames notebook execution when using a service account with oauth
+time: 2025-09-01T10:00:53.749318+02:00
+custom:
+    Author: jspenmar
+    Issue: "1231"

dbt-bigquery/src/dbt/adapters/bigquery/python_submissions.py

@@ -47,6 +47,8 @@
 # Time interval in seconds between successive polling attempts to check the
 # notebook job's status in BigFrames mode.
 _COLAB_POLL_INTERVAL = 30
+# Suffix used by service accounts.
+_SERVICE_ACCOUNT_SUFFIX = "iam.gserviceaccount.com"
 
 
 class _BigQueryPythonHelper(PythonJobHelper):
@@ -332,12 +334,19 @@ def _config_notebook_job(
                     url="https://www.googleapis.com/oauth2/v2/userinfo",
                     headers={"Authorization": f"Bearer {self._GoogleCredentials.token}"},
                 )
+
                 if response.status != 200:
                     raise DbtRuntimeError(
                         f"Failed to retrieve user info. Status: {response.status}, Body: {response.data}"
                     )
                 if user_email := json.loads(response.data).get("email"):
-                    notebook_execution_job.execution_user = user_email
+                    # In services such as Cloud Composer and Cloud Run, the authenticated user
+                    # is a service account with associated Application Default Credentials.
+                    # This does not require service account impersonation.
+                    if user_email and user_email.endswith(_SERVICE_ACCOUNT_SUFFIX):
+                        notebook_execution_job.service_account = user_email
+                    else:
+                        notebook_execution_job.execution_user = user_email
                 else:
                     raise DbtRuntimeError(
                         "Authorization request to get user failed to return an email."