DAGs: defining workflows of tasks

Use the LatestOnlyOperator to skip all tasks downstream of itself when a Dag run is not the latest: directly-downstream task1 is skipped for all non-latest runs, independent task2 runs in all scheduled periods, task3 receives a cascaded skip from task1 under the default all_success trigger rule, and task4 is not skipped because its trigger_rule is all_done. Set depends_on_past to True so a task runs only if its previous Dag run succeeded; the first automated run still runs. Other trigger rules include all_failed (upstream tasks failed or upstream_failed), one_success (at least one upstream succeeded), and always (no dependencies). removed is a terminal state that counts toward all_done. Teardown tasks default to all_done_setup_success, requiring at least one upstream setup success. Scope: Apache Airflow. Reviewed October 4, 2026.