comment on stackoverflow.com/questions/51664755

all_success_dag.py

from datetime import datetime
from airflow import DAG
from airflow.operators.python_operator import PythonOperator
from airflow.operators.dummy_operator import DummyOperator


dag = DAG(
    'test_branches',
    description='Test branches',
    catchup=False,
    schedule_interval='0 0 * * *',
    start_date=datetime(2018, 8, 1),
)


def python1():
    raise Exception('Test failure')

dummy1 = PythonOperator(
    task_id='python1',
    python_callable=python1,
    dag=dag
)

dummy2 = DummyOperator(
    task_id='dummy2',
    dag=dag,
    trigger_rule='all_done'
)

dummy3 = DummyOperator(
    task_id='dummy3',
    dag=dag,
    trigger_rule='all_done'
)

dummy4 = DummyOperator(
    task_id='dummy4',
    dag=dag,
    trigger_rule='all_success',
)

dummy1 >> dummy2
dummy1 >> dummy3
dummy2 >> dummy4
dummy3 >> dummy4