Allow user to supply croniter object, multiple cron strings or generator object to DAG

[themantalope]

Allow user to supply their own croniter object or datetime generator object to DAG

The user could create their own croniter object or their own object which generates python datetimes when creating a DAG, e.g.:

def my_great_generator(start_time):
   # great
   # code
   yield next_datetime

dt_gen = my_great_generator(datetime.datetime.now())

dag = DAG(
 description='does some great code execution on time!',
 datetimes_generator=dt_gen
...
)

Use case / motivation

Some jobs need to run at times that don't conform well to a single croniter schedule. You could combine multiple cron strings together or allow users to create their own generator.

Related Issues
issue 8469

[boring-cyborg]

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[eladkal]

FYI @BasPH - related to #24733

[cdchandani]

Is this feature implemented in airflow? I could see #24733 closed due to being stale , so not sure if it was implemented in some other commits .

[uranusjr]

This has been replaced by timetables. Feel free to contribute new timetables that supports the generator and croniter cases. The multiple cron use case will be tracked in #24733.