GitHub user LinasData created a discussion: ExternalTaskMarker not clearing
downstream tasks in Airflow 3.1.6
I am upgrading from Airflow 2.11.0 to Airflow 3.1.6 and noticed a change in
behavior regarding the `ExternalTaskMarker ` or maybe I am just using Airflow
3.1.6 wrong, so any help counts.
In Airflow 2.11.0, when I cleared a task upstream of an `ExternalTaskMarker
`(and selected the "Recursive" or "Downstream" clearing options), the
corresponding ExternalTaskSensor in the child DAG would also be cleared. In
Airflow 3, this relationship seems broken; clearing the parent task does not
trigger a clear on the child task.
We want to maintain task-level cross-DAG dependencies. While we are aware of
the new Assets feature in Airflow 3, we specifically need the granular control
provided by `ExternalTaskMarker` to ensure that re-running a specific parent
task forces the child sensor to reset.
**Environment**:
Airflow Version: 3.0.x
Executor: CeleryExecutor
Python Version: 3.12
Ran on docker container setup locally
Minimal working example:
```
# --- PARENT DAG ---
from datetime import datetime
from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.sensors.external_task import ExternalTaskMarker
with DAG(
dag_id='parent_dag',
start_date=datetime(2026, 1, 18),
schedule='@daily',
catchup=False
) as parent_dag:
task_1 = BashOperator(
task_id='echo_hello',
bash_command='echo HELLO!!!!'
)
# Marker to point to child_dag/receive_call
parent_trigger = ExternalTaskMarker(
task_id='parent_trigger',
external_dag_id='child_dag',
external_task_id='receive_call'
)
task_1 >> parent_trigger
# --- CHILD DAG ---
from airflow.sensors.external_task import ExternalTaskSensor
with DAG(
dag_id='child_dag',
start_date=datetime(2026, 1, 18),
schedule='@daily',
catchup=False
) as child_dag:
receive_call = ExternalTaskSensor(
task_id='receive_call',
external_dag_id='parent_dag',
external_task_id='parent_trigger'
)
child_task = BashOperator(
task_id='child_echo',
bash_command='echo DONE'
)
receive_call >> child_task
```
GitHub link: https://github.com/apache/airflow/discussions/60905
----
This is an automatically sent email for [email protected].
To unsubscribe, please send an email to: [email protected]
