Airflow BranchPythonOperator 不遵循指定的分支

Question

I have an AIRFLOW DAG with the following structure.

All the functions that start with "check*" are BranchPythonOperator, and the function exceptionControl is a ExecuteDagRunOperator that receives every error in order to handle them.

This is the DAG configuration:

checkCloudFunctions = BranchPythonOperator(
    task_id='checkCloudFunctions',
    python_callable=check_cloud_functions,
    provide_context=True,
    dag=dag)

checkSqlTables = BranchPythonOperator(
    task_id='checkSqlTables',
    python_callable=check_sql_tables,
    provide_context=True,
    dag=dag)

checkBigQueryTable = BranchPythonOperator(
    task_id='checkBigQueryTable',
    python_callable=check_big_query_table,
    provide_context=True,
    dag=dag)

labBuilt = DummyOperator(
    task_id='labBuilt',
    dag=dag)

exceptionControl = ExecuteDagRunOperator(
    task_id='exceptionControl',
    execute_dag_id="SYS_exception_control",
    python_callable=mediation.dag_trigger_exception,
    trigger_rule='one_success',
    dag=dag)

# graphs
checkCloudFunctions >> checkSqlTables
checkCloudFunctions >> exceptionControl

checkSqlTables >> checkBigQueryTable
checkSqlTables >> exceptionControl

checkBigQueryTable >> labBuilt
checkBigQueryTable >> exceptionControl

The problem is that checkSqlTables should follow to exception control but it skips and the DAG ends. The function returns "exceptionControl" as we can see in the checkSqlTables log:

   {base_task_runner.py:98} INFO - {python_operator.py:90} INFO - Done. Returned value was: exceptionControl
   {base_task_runner.py:98} INFO - {python_operator.py:118} INFO - Following branch exceptionControl
   {base_task_runner.py:98} INFO - {python_operator.py:119} INFO - Marking other directly downstream tasks as skipped
   {base_task_runner.py:98} INFO - {python_operator.py:128} INFO - Done.

I also played with the trigger_rule attribute (one_success, dummy...) but it doesn't seems to work.

If I delete the first step, it seems to work, so it seems it should be some kind of configuration problem with my dag.

Any ideas why the function checkSqlTables doesn't branch to exceptionControl?

EDIT: In a new deep reading to the Airflow Documentation I noticed that if a step mark a task as skipped, it will be skipped forever, so my code will never work with Branching Operators.

The solutions using branching consist on a dummy step before every step. But I have some DAG that have more than 10 steps and the schema will be completely a chaos.

Answer 1

This seems to be a bug discussed in here https://github.com/apache/airflow/issues/10725

Based on the above discussions, there is a fix merged here https://github.com/apache/airflow/pull/11120 .