kaxil commented on code in PR #75423:
URL: https://github.com/apache/airflow/pull/75423#discussion_r4354770030
##########
airflow-core/newsfragments/75423.bugfix.rst:
##########
@@ -0,0 +1 @@
+A task that runs entirely in the triggerer (``start_from_trigger=True``) now
records its rendered template fields, so the Rendered Templates tab shows them
instead of staying empty for the whole run.
Review Comment:
Can you drop this? airflow-core only takes `significant` newsfragments now,
for changes users must read before upgrading, and never for an ordinary bug fix
(see `contributing-docs/18_contribution_workflow.rst`).
##########
airflow-core/src/airflow/jobs/triggerer_job_runner.py:
##########
@@ -1467,6 +1475,32 @@ def create_runtime_ti(
),
)
+ async def record_rendered_fields(self, runtime_ti: RuntimeTaskInstance,
context: Context) -> None:
+ """
+ Record the rendered template fields of a task that starts from the
triggerer.
+
+ Such a task never starts in a worker, so nothing else records them and
the Rendered
+ Templates tab stays empty for the whole run. Rendering is best effort:
a task whose
+ fields cannot be rendered here still has a trigger to run.
+ """
+ # Reused rather than reimplemented so core cannot drift from the
redaction the worker applies.
+ from airflow.sdk.execution_time.task_runner import
_serialize_rendered_fields # noqa: SDK001
+
+ try:
+ context["task"] = runtime_ti.task
+ runtime_ti.render_templates(context=context,
jinja_env=runtime_ti.task.dag.get_template_env())
Review Comment:
In production this never gets past this line. `create_runtime_ti` builds the
task with `DagSerialization.from_dict(...).get_task(...)`, so `runtime_ti.task`
is a core `SerializedBaseOperator` and `.dag` is a `SerializedDAG`, and neither
has `get_template_env` or `render_template_fields`. The `AttributeError` is
caught below, so every start-from-trigger task logs "Failed to render template
fields" with a traceback and nothing is sent. I ran `record_rendered_fields` on
a task built that way: `asend` was never awaited and the log had
`'SerializedDAG' object has no attribute 'get_template_env'`.
Adding those methods to the serialized classes wouldn't get there either.
Rendering an operator's fields needs things the serialized Dag doesn't carry
(`user_defined_macros`, `user_defined_filters`, `template_searchpath` for
`template_ext` files), and the triggerer doesn't load Dag bundles. #53071 had
the triggerer load the Dag to render task fields and was reverted in #55037 for
that reason.
What the triggerer can render is what it already renders: `BaseTrigger`
renders the operator template fields passed through
`start_trigger_args.trigger_kwargs` (`target_time` for `DateTimeSensorAsync`,
the case in the issue). Recording those after
`trigger.render_template_fields(context)` would work without the Dag file,
though it only covers the fields the trigger receives.
##########
airflow-core/tests/unit/jobs/test_triggerer_job.py:
##########
@@ -4007,3 +4007,65 @@ async def fake_run():
log.get("event") == "Trigger fired event payload" and
log.get("result") == TriggerEvent(payload)
for log in debug_logs
), "Full event payload must be logged at DEBUG level"
+
+
+class _TemplatedOperator(BaseOperator):
+ """Minimal operator with a templated field, for the start-from-trigger
rendering tests."""
+
+ template_fields = ("greeting",)
+
+ def __init__(self, *, greeting: str, **kwargs):
+ super().__init__(**kwargs)
+ self.greeting = greeting
+
+ def execute(self, context):
+ raise AssertionError("start_from_trigger tasks never execute in a
worker")
+
+
+def _runtime_ti_with_templated_task(greeting: str):
+ from airflow.sdk.execution_time.task_runner import RuntimeTaskInstance
+
+ with DAG("rendered_fields_dag", schedule=None,
start_date=timezone.datetime(2026, 1, 1)):
+ task = _TemplatedOperator(task_id="templated", greeting=greeting)
+
+ return RuntimeTaskInstance.model_construct(
Review Comment:
These tests hand `model_construct` an SDK `BaseOperator`, but production
builds the TI through `TriggerRunner.create_runtime_ti(ti,
DagSerialization.to_dict(dag), dag_run_data)`, which is why they pass while the
real path raises. Building it that way would have caught the problem above. The
new `SetRenderedFields` branch in `_handle_request` also has no test.
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