Airflow DAG success callback

So if I understand correctly, the last step of your DAG is, in case of success, to call back to some other system. So I would encourage you to model your DAG exactly that way.

Why would you try to hide that part from the logic of your DAG? That's exactly what the up/downstream modeling is for. Hiding part of the DAG logic for the sake of the graph's aesthetics sounds like a bad tradeoff to me.

I would discourage you to set the callback task as downstream to all tasks, it should be downstream only to final tasks in the DAG.

Don't know how much it helps you now, but the functionality you are looking for exists in Airflow 1.10... a DAG has an on_success_callback

https://airflow.apache.org/code.html#airflow.models.DAG