BasPH commented on code in PR #24733:
URL: https://github.com/apache/airflow/pull/24733#discussion_r909893220
##########
docs/apache-airflow/concepts/dags.rst:
##########
@@ -140,28 +140,41 @@ You can also provide an ``.airflowignore`` file inside
your ``DAG_FOLDER``, or a
Running DAGs
------------
-DAGs will run in one of two ways:
+A DAG can run in two ways:
- - When they are *triggered* either manually or via the API
- - On a defined *schedule*, which is defined as part of the DAG
+ - *Manually triggered* via the UI or API
+ - Or *scheduled*, defined by ``schedule_interval`` on the DAG. For example::
-DAGs do not *require* a schedule, but it's very common to define one. You
define it via the ``schedule_interval`` argument, like this::
- with DAG("my_daily_dag", schedule_interval="@daily"):
- ...
+ from airflow.models import DAG
-The ``schedule_interval`` argument takes any value that is a valid `Crontab
<https://en.wikipedia.org/wiki/Cron>`_ schedule value, so you could also do::
- with DAG("my_daily_dag", schedule_interval="0 * * * *"):
+ with DAG("my_dag", schedule_interval="0 0 * * *"):
...
-.. tip::
- For more information on ``schedule_interval`` values, see :doc:`DAG Run
</dag-run>`.
+This DAG will run every day at 00:00, as defined by the cron expression given
to ``schedule_interval``. The value of ``schedule_interval`` can take several
types:
+
++------------------------------------------+----------------------------------------------------------------------------------------------------------------------+--------------------------------------+
+| Type | When to use
| Example |
++==========================================+======================================================================================================================+======================================+
+| ``None`` | No schedule, use for manually
triggered DAGs
| ``None`` |
++------------------------------------------+----------------------------------------------------------------------------------------------------------------------+--------------------------------------+
+| Cron expression (``str``) | To run at cron-based intervals
+ ``"0 0 * * *"`` |
++------------------------------------------+----------------------------------------------------------------------------------------------------------------------+--------------------------------------+
+| Cron preset (``str``) | Convenience cron expression for
readability
+ ``"@daily"`` |
++------------------------------------------+----------------------------------------------------------------------------------------------------------------------+--------------------------------------+
+| List of cron expressions/presets | To run at intervals that cannot
be expressed by a single cron expression.
+ ``["0 3 * * *", "0 0 * * MON,TUE"]`` |
Review Comment:
I can be both "and" and "or". For example, when given `["0 3 * * MON,TUE",
"@daily"]`, each expression is looked up in the cron presets and converted if
found. Shall I convert to "and/or"?
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