[AIRFLOW-3004] Add config disabling scheduler cron (apache#3899)

Author: xales

airflow/config_templates/default_airflow.cfg

@@ -488,6 +488,10 @@ max_threads = 2
 
 authenticate = False
 
+# Turn off scheduler use of cron intervals by setting this to False.
+# DAGs submitted manually in the web UI or with trigger_dag will still run.
+use_job_schedule = True
+
 [ldap]
 # set this to ldaps://<your.ldap.server>:<port>
 uri =

airflow/jobs.py

@@ -785,7 +785,7 @@ def create_dag_run(self, dag, session=None):
         for a DAG based on scheduling interval
         Returns DagRun if one is scheduled. Otherwise returns None.
         """
-        if dag.schedule_interval:
+        if dag.schedule_interval and conf.getboolean('scheduler', 'USE_JOB_SCHEDULE'):
             active_runs = DagRun.find(
                 dag_id=dag.dag_id,
                 state=State.RUNNING,