Fixes #21106: Support owner extraction from serialized Airflow DAGs (#22071)

* fix(airflow): correctly extract owners from serialized Airflow DAGs

Airflow serialization format wraps tasks under `__var` and `__type`.
Previously, the OpenMetadata Airflow connector failed to extract task owners properly in this format.

This patch:
- Flattens `__var` when parsing task owners
- Fallbacks to `default_args["owner"]` if no task-level owner is explicitly present
- Ensures correct DAG owner is picked as the most common task owner
- Handles compatibility with older Airflow versions

Fixes: #21106

* test(airflow): add tests for owner extraction from serialized Airflow DAGs

Adds new test cases to validate owner extraction logic:
- Owners from serialized task format (`__var`)
- Fallback to `default_args['owner']` if task owners are missing
- Resolution of most common owner
- Compatibility with unstructured or missing owners

* remove test version specific comment

* simplify comments and warnings

* fix return statement

* fixing formatting

* adding handling of default args

* fixing and adding more tests

ingestion/src/metadata/ingestion/source/pipeline/airflow/metadata.py

@@ -414,18 +414,41 @@ class AirflowSource(PipelineServiceSource):
         - `owners`: Applied at the tasks. In Airflow's source code, DAG ownership is then a
           list joined with the owners of all the tasks.
 
-        We will pick the owner from the tasks that appears in most tasks.
+        We will pick the owner from the tasks that appears in most tasks,
+        or fall back to the default_args owner if available.
         """
         try:
-            if self.source_config.includeOwners:
-                task_owners = [
-                    task.get("owner")
-                    for task in data.get("tasks", [])
-                    if task.get("owner") is not None
-                ]
-                if task_owners:
-                    most_common_owner, _ = Counter(task_owners).most_common(1)[0]
-                    return most_common_owner
+            if not self.source_config.includeOwners:
+                return None
+
+            tasks = data.get("tasks", [])
+            task_owners = []
+
+            # Handle default_args.owner (wrapped or not)
+            default_args = data.get("default_args", {})
+            if isinstance(default_args, dict) and "__var" in default_args:
+                default_args = default_args["__var"]
+            default_owner = default_args.get("owner")
+
+            for task in tasks:
+                # Flatten serialized task
+                task_data = (
+                    task.get("__var")
+                    if isinstance(task, dict) and "__var" in task
+                    else task
+                )
+
+                owner = task_data.get("owner") or default_owner
+
+                if owner:
+                    task_owners.append(owner)
+
+            if task_owners:
+                most_common_owner, _ = Counter(task_owners).most_common(1)[0]
+                return most_common_owner
+
+            return default_owner
+
         except Exception as exc:
             self.status.warning(
                 data.get("dag_id"), f"Could not extract owner information due to {exc}"

ingestion/tests/unit/topology/pipeline/test_airflow.py

@@ -272,3 +272,51 @@ class TestAirflow(TestCase):
             }
         }
         self.assertEqual(get_schedule_interval(pipeline_data), "*/2 * * * *")
+
+    def test_get_dag_owners_with_serialized_tasks(self):
+        # Case 1: All tasks have no explicit owner → fallback to default_args
+        data = {
+            "default_args": {"__var": {"owner": "default_owner"}},
+            "tasks": [
+                {"__var": {"task_id": "t1"}, "__type": "EmptyOperator"},
+                {"__var": {"task_id": "t2"}, "__type": "EmptyOperator"},
+            ],
+        }
+        self.assertEqual("default_owner", self.airflow.fetch_dag_owners(data))
+
+        # Case 2: One task explicitly overrides the owner → tie between two owners
+        data = {
+            "default_args": {"__var": {"owner": "default_owner"}},
+            "tasks": [
+                {
+                    "__var": {"task_id": "t1"},
+                    "__type": "EmptyOperator",
+                },  # uses default_owner
+                {
+                    "__var": {"task_id": "t2", "owner": "overridden_owner"},
+                    "__type": "EmptyOperator",
+                },
+            ],
+        }
+        result = self.airflow.fetch_dag_owners(data)
+        self.assertIn(result, {"default_owner", "overridden_owner"})
+
+        # Case 3: One owner is majority -> must return that owner
+        data = {
+            "default_args": {"__var": {"owner": "default_owner"}},
+            "tasks": [
+                {
+                    "__var": {"task_id": "t1", "owner": "overridden_owner"},
+                    "__type": "EmptyOperator",
+                },
+                {
+                    "__var": {"task_id": "t2", "owner": "overridden_owner"},
+                    "__type": "EmptyOperator",
+                },
+                {
+                    "__var": {"task_id": "t3", "owner": "another_owner"},
+                    "__type": "EmptyOperator",
+                },
+            ],
+        }
+        self.assertEqual("overridden_owner", self.airflow.fetch_dag_owners(data))