How the first DAG run is triggered by CronTriggerTimetable

[kimminw00]

import pendulum

from airflow import DAG
from airflow.operators.bash import BashOperator

from airflow.timetables.trigger import CronTriggerTimetable

with DAG(
    dag_id="example_test_schedule",
    schedule=CronTriggerTimetable("0 12 * * *", timezone="Asia/Seoul"),
    start_date=pendulum.datetime(2021, 1, 1, tz="Asia/Seoul"),
    catchup=False,
    tags=["example"],
) as dag:
    bash_task = BashOperator(
        task_id="bash_task",
        bash_command='echo "hello world"',
    )

If I enable the DAG using the CronTriggerTimetable at 3PM on November 15th, CronTriggerTimetable immediately trigger a new DAG run which is supposed to trigger at 12AM on November 15th.

Here is an example showing how the first DAG run is triggered. Supposes there is a cron expression @daily or 0 0 * * *, which is aimed to run at 12AM every day. If you enable DAGs using the two timetables at 3PM on January 31st, CronTriggerTimetable will trigger a new DAG run at 12AM on February 1st. CronDataIntervalTimetable, on the other hand, will immediately trigger a new DAG run which is supposed to trigger at 12AM on January 31st if the DAG had been enabled beforehand.

From the above lines, I think that CronTriggerTimetable should trigger a new DAG run at 12AM on November 16th and not immediately trigger a new DAG run which is supposed to trigger at 12AM on November 15th. Is there something I missed?

Environment

Airflow 2.7.2

Reference

https://airflow.apache.org/docs/apache-airflow/stable/authoring-and-scheduling/timetable.html#the-time-when-a-dag-run-is-triggered

[jojaeng2]

hello, @kimminw00
Did you solve this problem by any chance? I wanted the same usability, so I used CronTriggerTimetable, but if I change it to the enable state, it will be executed once. Please help me if you solved it.

[kimminw00]

I haven't solved it yet! But I keep looking for solutions.

[jojaeng2]

Hello, I'm going to solve this problem and share it with you,

1. Set start_date to now.
2. Use cron expressions using CronTriggerTimable

I think it will be helpful.

[jojaeng2]

In airflow 2.8.0, I solved it this way. I hope it helps

[engg14000]

Thanks @jojaeng2! The workaround you suggested helps! However, the expected behavior is that CronTriggerTimetable should skip the immediate run, whereas CronDataIntervalTimetable will perform an immediate run.

[jojaeng2]

Hello @engg14000 , I don't understand the comments you left, can you explain a little more?