Airflow: schedule_interval = '@once'

Question

What is the semantic difference between setting airflow's schedule_interval to "@once" vs. None?

If I understand correctly, they both will require manual triggering of the dag in order to run. Is this correct?

Answer 1

Only if set to None you have to trigger it manually - it won't be scheduled at all. If you set it to @Once it will run exactly one time (and only one time) - see the airflow docs.