Pawel Bartoszek created AIRFLOW-4404:
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Summary: Improve support of cron-style jobs
Key: AIRFLOW-4404
URL: https://issues.apache.org/jira/browse/AIRFLOW-4404
Project: Apache Airflow
Issue Type: Improvement
Components: scheduler
Affects Versions: 1.10.3
Reporter: Pawel Bartoszek
The cron like jobs are supported by Airflow with one downside: On the the very
first job deployment (completely new DAG) an extra DAG run will be created for
the latest passed period.
When DAG is redeployed (dag name stays the same) then DB already contains the
latest run and scheduler will work as a genuine cron scheduler.
To better describe what I mean I prepared an example:
{code:java}
with DAG(
dag_id="dag",
start_date=datetime(2019, 4, 1),
schedule_interval="0 2 * * *",
default_view="graph",
orientation="TB",
concurrency=1,
max_active_runs=1,
catchup=False) as dag:{code}
I deploy 'dag' for the first time and system time is *2019-04-03 3 PM*.
Airflow will create a DAG run with execution date of 2019-04-02 2 AM straight
after the deployment. However, when a new version of 'dag' is redeployed the
next run will be triggered according to cron expression ie with the deployment
done at 2019-04-03 6 PM the next dag run will be at 2019-04-04 2 AM.
*The requested change*
FroM cron-style jobs Airflow should work as a unix cron scheduler ie should
start very first dag run only after current system time is after next cron
expression date so that no extra run is created.
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