Asquator commented on code in PR #61274:
URL: https://github.com/apache/airflow/pull/61274#discussion_r2775447876
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airflow-core/src/airflow/models/dagrun.py:
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@@ -1410,24 +1416,44 @@ def notify_dagrun_state_changed(self, msg: str):
# or LocalTaskJob, so we don't want to "falsely advertise" we notify
about that
@provide_session
- def get_last_ti(self, dag: SerializedDAG, session: Session = NEW_SESSION)
-> TI | None:
- """Get Last TI from the dagrun to build and pass Execution context
object from server to then run callbacks."""
+ def get_first_ti_causing_failure(self, dag: SerializedDAG, session:
Session = NEW_SESSION) -> TI | None:
+ """
+ Get the first task instance that would cause a leaf task to fail the
run.
+ """
+
tis = self.get_task_instances(session=session)
- # tis from a dagrun may not be a part of dag.partial_subset,
- # since dag.partial_subset is a subset of the dag.
- # This ensures that we will only use the accessible TI
- # context for the callback.
+
+ failed_leaf_tis = [
+ ti for ti in self._tis_for_dagrun_state(dag=dag, tis=tis)
+ if ti.state in State.failed_states
+ ]
+
+ if not failed_leaf_tis:
+ return None
+
if dag.partial:
- tis = [ti for ti in tis if not ti.state == State.NONE]
- # filter out removed tasks
- tis = natsorted(
- (ti for ti in tis if ti.state != TaskInstanceState.REMOVED),
- key=lambda ti: ti.task_id,
- )
- if not tis:
- return None
- ti = tis[-1] # get last TaskInstance of DagRun
- return ti
+ tis = [
+ ti for ti in tis if not ti.state in (
+ State.NONE, TaskInstanceState.REMOVED
+ )
+ ]
+
+ # Collect all task IDs on failure paths
+ failure_path_task_ids = set()
+ for failed_leaf in failed_leaf_tis:
+ leaf_task = dag.get_task(failed_leaf.task_id)
+ upstream_ids = leaf_task.get_flat_relative_ids(upstream=True)
+ failure_path_task_ids.update(upstream_ids)
+ failure_path_task_ids.add(failed_leaf.task_id)
+
+ # Find failed tasks on possible failure paths
+ failed_on_paths = [
+ ti for ti in tis
+ if ti.task_id in failure_path_task_ids and ti.state ==
State.FAILED
+ ]
+
+ return min(failed_on_paths, key=lambda ti: ti.end_date, default=None)
Review Comment:
> Why shouldn't we return multiple tasks if a few of them were running
concurrently?
Unfortunately, the current `Context` has to provide at least one TI under
the `"ti"` key, even on DAG failure callbacks. I don't know whether it's good
or bad, probably bad, but I decided to adhere to this rule for back comp. I
think the context user can still access other tasks in the DAG, can't he?
> And why filter by end_date and not start_date?
A good point. Logically, I wanted to return the task that ended last and
could cause the DAG to fail. On the second thought, maybe it will be wiser to
filter by `start_date` since many tasks will be failed manually after the DAG
fails.
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