crontab

A Crontab can be used as the run_every value of a periodic task entry to add :manpage:crontab(5)-like scheduling.

Attributes

Attribute	Type	Description
minute	set = *	A (list of) integers from 0-59 or a string representing a Crontab pattern that represent the minutes of an hour of when execution should occur.
hour	set = *	A (list of) integers from 0-23 or a string representing a Crontab pattern that represent the hours of a day of when execution should occur.
day_of_week	set = *	A (list of) integers from 0-6 (Sunday=0) or a string representing a Crontab pattern that represent the days of a week that execution should occur.
day_of_month	set = *	A (list of) integers from 1-31 or a string representing a Crontab pattern that represents the days of the month that execution should occur.
month_of_year	set = *	A (list of) integers from 1-12 or a string representing a Crontab pattern that represents the months of the year during which execution can occur.
nowfun	callable	Function returning the current date and time (datetime.datetime).
app	[Celery](../app/base/celery.md?sid=celery_app_base_celery)	The Celery app instance.

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Constructor

Signature

def crontab(
    minute: Cronspec = '*',
    hour: Cronspec = '*',
    day_of_week: Cronspec = '*',
    day_of_month: Cronspec = '*',
    month_of_year: Cronspec = '*',
    **kwargs: Any
) - > None

Parameters

Name	Type	Description
minute	Cronspec = '*'	Minute(s) of an hour when the task should run (0-59).
hour	Cronspec = '*'	Hour(s) of a day when the task should run (0-23).
day_of_week	Cronspec = '*'	Day(s) of the week when the task should run (0-6, Sunday=0).
day_of_month	Cronspec = '*'	Day(s) of the month when the task should run (1-31).
month_of_year	Cronspec = '*'	Month(s) of the year when the task should run (1-12).
**kwargs	Any	Additional keyword arguments passed to the BaseSchedule parent class.

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Methods

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from_string()

@classmethod
def from_string(
    crontab: str
) - > [crontab](crontab.md?sid=celery_schedules_crontab)

Create a Crontab from a cron expression string. For example crontab.from_string('* * * * *').

Parameters

Name	Type	Description
crontab	str	A space-separated string containing five cron fields: minute, hour, day of month, month, and day of week

Returns

Type	Description
[crontab](crontab.md?sid=celery_schedules_crontab)	A new crontab instance initialized with the parsed schedule components

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remaining_delta()

@classmethod
def remaining_delta(
    last_run_at: datetime,
    tz: tzinfo | None,
    ffwd: type
) - > tuple[datetime, Any, datetime]

Calculates the time difference between the last run and the next scheduled execution based on the crontab rules.

Parameters

Name	Type	Description
last_run_at	datetime	The timestamp when the task was last executed
tz	`tzinfo	None`
ffwd	type	The fast-forward utility class used to calculate time jumps

Returns

Type	Description
tuple[datetime, Any, datetime]	A tuple containing the localized last run time, the fast-forward delta to the next run, and the localized current time

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remaining_estimate()

@classmethod
def remaining_estimate(
    last_run_at: datetime,
    ffwd: type
) - > timedelta

Estimate of next run time. Returns when the periodic task should run next as a :class:~datetime.timedelta.

Parameters

Name	Type	Description
last_run_at	datetime	The timestamp of the last execution to calculate the next interval from
ffwd	type	The fast-forward utility class used for time calculations

Returns

Type	Description
timedelta	The duration of time remaining until the next scheduled execution

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is_due()

@classmethod
def is_due(
    last_run_at: datetime
) - > tuple[bool, datetime]

Return tuple of (is_due, next_time_to_run). If :setting:beat_cron_starting_deadline has been specified, the scheduler will make sure that the last_run_at time is within the deadline.

Parameters

Name	Type	Description
last_run_at	datetime	The timestamp of the last successful execution to check against the schedule and deadline

Returns

Type	Description
tuple[bool, datetime]	A tuple where the first element indicates if the task is ready to run, and the second is the time remaining until the next run

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