When you deploy a new DAG with catchup=True Airflow scheduler automatically schedules all the tasks from the start_date till now. It finishes and you get a lot of dark green balls meaning those DAGs in the past have been run.
But now you want to add new tasks to the past DAG runs. What should I do to make the old DAG runs recognize the new tasks and run them?
You should clear the old DAG runs (can also be done in the GUI). The cleared runs will be rescheduled including the newly added tasks.
If you have access to airflow cli, you can use the backfill command to run the new task for any period of time. The command does not re-run any of the tasks that have already run in subsequent dag runs.
Start and end dates to backfill are optional, so you could just run
$ airflow backfill your_dag_id
