nested_branch_dag

Example DAG demonstrating a workflow with nested branching. The join tasks are created with none_failed_or_skipped trigger rule such that they are skipped whenever their corresponding BranchPythonOperator are skipped.

Airflow Fundamentals


Providers:

Run this DAG

1. Install the Astronomer CLI:Skip if you already have the CLI

2. Initate the project in a local directory:

3. Copy and paste the code below into a file in the

dags
directory.

4. Run the DAG from the local directory where the project was initiated:

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"""
Example DAG demonstrating a workflow with nested branching. The join tasks are created with
``none_failed_or_skipped`` trigger rule such that they are skipped whenever their corresponding
``BranchPythonOperator`` are skipped.
"""
from airflow.models import DAG
from airflow.operators.dummy import DummyOperator
from airflow.operators.python import BranchPythonOperator
from airflow.utils.dates import days_ago
with DAG(
dag_id="example_nested_branch_dag", start_date=days_ago(2), schedule_interval="@daily", tags=["example"]
) as dag:
branch_1 = BranchPythonOperator(task_id="branch_1", python_callable=lambda: "true_1")
join_1 = DummyOperator(task_id="join_1", trigger_rule="none_failed_or_skipped")
true_1 = DummyOperator(task_id="true_1")
false_1 = DummyOperator(task_id="false_1")
branch_2 = BranchPythonOperator(task_id="branch_2", python_callable=lambda: "true_2")
join_2 = DummyOperator(task_id="join_2", trigger_rule="none_failed_or_skipped")
true_2 = DummyOperator(task_id="true_2")
false_2 = DummyOperator(task_id="false_2")
false_3 = DummyOperator(task_id="false_3")
branch_1 >> true_1 >> join_1
branch_1 >> false_1 >> branch_2 >> [true_2, false_2] >> join_2 >> false_3 >> join_1