> Airflow requires task queues (e.g. celery), message broker (e.g. rabbitmq), a web service, a scheduler service, and a database. You also need worker clusters to read from your task queues and execute jobs.

All these are supported but the scheduler is pretty much the only requirement.

Source: been running Airflow for the last two years without a worker cluster, without having celery/rabbitmq installed and sometimes without even an external database (i.e. a plan sqlite file).