Apache Airflow 129 (Apache-2.0, github.com/apache/airflow (https://github.com/apache/airflow 47,037 )) is not one program but a set of cooperating services around a database. Knowing which component does what tells you where to look when a task sits in "queued" forever, why a DAG change has not appeared, and what to scale. Everything in this section was observed on the Airflow 3.3.2 stack that Airflow in Docker Compose builds: five containers, the LocalExecutor, and two DAGs.
