amoghrajesh opened a new pull request, #55542:
URL: https://github.com/apache/airflow/pull/55542
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closes: https://github.com/apache/airflow/issues/55464
## Problem
When custom notifiers extending BaseNotifier attempted to access XCom
via `ti.xcom_pull()` in success/failure callbacks, they failed with
ValidationError because the DAG processor didn't support XCom message
types in the supervisor.
This fix adds support for xcom operations in the DAG processor by:
- Adding XCom request types (GetXCom, GetXComSequenceSlice, etc.) to
`ToManager`
- Adding XCom response types (XComResult, XComSequenceSliceResult, etc.) to
`ToDagProcessor`
- Implementing XCom request handlers in
`DagFileProcessorProcess._handle_request()`
## Testing
DAG used:
```
from airflow.sdk import DAG
from airflow.providers.standard.operators.python import PythonOperator
from datetime import datetime
from airflow.sdk.bases.notifier import BaseNotifier
from airflow.sdk.definitions.context import Context
class XComNotifier(BaseNotifier):
def notify(self, context: Context) -> None:
ti = context['ti']
d = context['dag']
task_ids = list(d.task_dict.keys())
print("trying pulling task ids:", task_ids)
report_df = ti.xcom_pull(key='report_df', task_ids=task_ids)
print(f"XCom data: {report_df}")
def push_data(**context):
# Push some XCom data
context['ti'].xcom_push(key='report_df', value='test data')
return 'success'
with DAG(
dag_id='xcom_notifier_repro',
start_date=datetime(2024, 1, 1),
schedule=None,
on_success_callback=XComNotifier(),
catchup=False,
) as dag:
task1 = PythonOperator(
task_id='push_xcom_data',
python_callable=push_data,
)
task1
```
Earlier:
```
2025-09-10 10:31:54 [error ] Unable to decode message [supervisor]
body={'key': 'report_df', 'dag_id': 'Oracle-DB-Check', 'run_id':
'manual__2025-09-10T15:31:49.020767+00:00', 'task_id': 'check_dw_prod',
'start': None, 'stop': None, 'step': None, 'include_prior_dates': False,
'type': 'GetXComSequenceSlice'}
2025-09-10T15:31:54.097275837Z ╭─────────────────────────────── Traceback
(most recent call last) ────────────────────────────────╮
2025-09-10T15:31:54.097279587Z │
/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/execution_time/supervisor.py:601
│
2025-09-10T15:31:54.097281128Z │ in handle_requests
│
2025-09-10T15:31:54.097282170Z │
│
2025-09-10T15:31:54.097283337Z │ 598 │ │ │ request = yield
│
2025-09-10T15:31:54.097284587Z │ 599 │ │ │
│
2025-09-10T15:31:54.097285587Z │ 600 │ │ │ try:
│
2025-09-10T15:31:54.097286670Z │ ❱ 601 │ │ │ │ msg =
self.decoder.validate_python(request.body) │
2025-09-10T15:31:54.097287837Z │ 602 │ │ │ except Exception:
│
2025-09-10T15:31:54.097289003Z │ 603 │ │ │ │
log.exception("Unable to decode message", body=request.body) │
2025-09-10T15:31:54.097290795Z │ 604 │ │ │ │ continue
│
2025-09-10T15:31:54.097291837Z │
│
2025-09-10T15:31:54.097292795Z │
╭─────────────────────────────────────────── locals
───────────────────────────────────────────╮ │
2025-09-10T15:31:54.097299003Z │ │ log =
<BoundLoggerLazyProxy(logger=None, wrapper_class=None, processors=None,
│ │
2025-09-10T15:31:54.097301128Z │ │ context_class=None,
initial_values={'logger_name': 'supervisor'}, │ │
2025-09-10T15:31:54.097302795Z │ │ logger_factory_args=())>
│ │
2025-09-10T15:31:54.097304087Z │ │ msg = MaskSecret(
│ │
2025-09-10T15:31:54.097305378Z │ │ │
value='<secret_value_hidden>', │ │
2025-09-10T15:31:54.097306670Z │ │ │ name='dispatch_api_key',
│ │
2025-09-10T15:31:54.097309837Z │ │ │ type='MaskSecret'
│ │
2025-09-10T15:31:54.097311295Z │ │ )
│ │
2025-09-10T15:31:54.097312337Z │ │ request = _RequestFrame(
│ │
2025-09-10T15:31:54.097313503Z │ │ │ id=1,
│ │
2025-09-10T15:31:54.097314628Z │ │ │ body={
│ │
2025-09-10T15:31:54.097315795Z │ │ │ │ 'key': 'report_df',
│ │
2025-09-10T15:31:54.097321962Z │ │ │ │ 'dag_id':
'Oracle-DB-Check', │ │
2025-09-10T15:31:54.097323253Z │ │ │ │ 'run_id':
'manual__2025-09-10T15:31:49.020767+00:00', │ │
2025-09-10T15:31:54.097324503Z │ │ │ │ 'task_id':
'check_dw_prod', │ │
2025-09-10T15:31:54.097325795Z │ │ │ │ 'start': None,
│ │
2025-09-10T15:31:54.097327087Z │ │ │ │ 'stop': None,
│ │
2025-09-10T15:31:54.097328337Z │ │ │ │ 'step': None,
│ │
2025-09-10T15:31:54.097329462Z │ │ │ │ 'include_prior_dates':
False, │ │
2025-09-10T15:31:54.097331628Z │ │ │ │ 'type':
'GetXComSequenceSlice' │ │
2025-09-10T15:31:54.097332753Z │ │ │ }
│ │
2025-09-10T15:31:54.097333837Z │ │ )
│ │
2025-09-10T15:31:54.097334878Z │ │ self = <DagFileProcessorProcess
id=UUID('01993441-38d2-7bcc-8bbd-53306533f95a') pid=177> │ │
2025-09-10T15:31:54.097336670Z │
╰──────────────────────────────────────────────────────────────────────────────────────────────╯
│
2025-09-10T15:31:54.097339170Z │
│
2025-09-10T15:31:54.097340253Z │
/home/airflow/.local/lib/python3.12/site-packages/pydantic/type_adapter.py:421
in │
2025-09-10T15:31:54.097341462Z │ validate_python
│
2025-09-10T15:31:54.097342545Z │
│
2025-09-10T15:31:54.097343545Z │ 418 │ │ │ │
code='validate-by-alias-and-name-false', │
2025-09-10T15:31:54.097344837Z │ 419 │ │ │ )
│
2025-09-10T15:31:54.097346045Z │ 420 │ │
│
2025-09-10T15:31:54.097347128Z │ ❱ 421 │ │ return
self.validator.validate_python( │
2025-09-10T15:31:54.097348378Z │ 422 │ │ │ object,
│
2025-09-10T15:31:54.097349420Z │ 423 │ │ │ strict=strict,
│
2025-09-10T15:31:54.097350378Z │ 424 │ │ │
from_attributes=from_attributes, │
2025-09-10T15:31:54.097351420Z │
│
2025-09-10T15:31:54.097352462Z │
╭─────────────────────────────────────────── locals
───────────────────────────────────────────╮ │
2025-09-10T15:31:54.097353920Z │ │ by_alias = None
│ │
2025-09-10T15:31:54.097355087Z │ │ by_name = None
│ │
2025-09-10T15:31:54.097357045Z │ │ context = None
│ │
2025-09-10T15:31:54.097358212Z │ │ experimental_allow_partial = False
│ │
2025-09-10T15:31:54.097359295Z │ │ from_attributes = None
│ │
2025-09-10T15:31:54.097360420Z │ │ object = {
│ │
2025-09-10T15:31:54.097361670Z │ │ │ 'key':
'report_df', │ │
2025-09-10T15:31:54.097363545Z │ │ │
'dag_id': 'Oracle-DB-Check', │ │
2025-09-10T15:31:54.097364837Z │ │ │
'run_id': 'manual__2025-09-10T15:31:49.020767+00:00', │ │
2025-09-10T15:31:54.097365962Z │ │ │
'task_id': 'check_dw_prod', │ │
2025-09-10T15:31:54.097367212Z │ │ │ 'start':
None, │ │
2025-09-10T15:31:54.097368295Z │ │ │ 'stop':
None, │ │
2025-09-10T15:31:54.097369545Z │ │ │ 'step':
None, │ │
2025-09-10T15:31:54.097370587Z │ │ │
'include_prior_dates': False, │ │
2025-09-10T15:31:54.097371753Z │ │ │ 'type':
'GetXComSequenceSlice' │ │
2025-09-10T15:31:54.097373795Z │ │ }
│ │
2025-09-10T15:31:54.097374837Z │ │ self =
TypeAdapter(Annotated[Union[DagFileParsingResult, │ │
2025-09-10T15:31:54.097376003Z │ │
GetConnection, GetVariable, PutVariable, DeleteVariable, │ │
2025-09-10T15:31:54.097377253Z │ │
GetPrevSuccessfulDagRun, GetPreviousDagRun, MaskSecret], │ │
2025-09-10T15:31:54.097378295Z │ │
FieldInfo(annotation=NoneType, required=True, │ │
2025-09-10T15:31:54.097379712Z │ │
discriminator='type')]) │ │
2025-09-10T15:31:54.097380920Z │ │ strict = None
│ │
2025-09-10T15:31:54.097382128Z │
╰──────────────────────────────────────────────────────────────────────────────────────────────╯
│
2025-09-10T15:31:54.097383295Z
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
2025-09-10T15:31:54.097384420Z ValidationError: 1 validation error for
2025-09-10T15:31:54.097385337Z
tagged-union[DagFileParsingResult,GetConnection,GetVariable,PutVariable,DeleteVariable,GetPrevSucces
2025-09-10T15:31:54.097386462Z sfulDagRun,GetPreviousDagRun,MaskSecret]
2025-09-10T15:31:54.097387295Z Input tag 'GetXComSequenceSlice' found
using 'type' does not match any of the expected tags:
2025-09-10T15:31:54.097388378Z 'DagFileParsingResult', 'GetConnection',
'GetVariable', 'PutVariable', 'DeleteVariable',
2025-09-10T15:31:54.097389545Z 'GetPrevSuccessfulDagRun',
'GetPreviousDagRun', 'MaskSecret' [type=union_tag_invalid,
2025-09-10T15:31:54.097391545Z input_value={'key': 'report_df', 'dag...
'GetXComSequenceSlice'}, input_type=dict]
2025-09-10T15:31:54.097392878Z For further information visit
https://errors.pydantic.dev/2.11/v/union_tag_invalid
```
Now:
<img width="1172" height="150" alt="image"
src="https://github.com/user-attachments/assets/c5546199-403b-46cb-9978-3ea0adc3d607";
/>
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