Cron triggers

Creating Cron tasks

Cron tasks run repeatedly on a specified cron schedule. Define the task that the automation submits, then register its implementation with a runner.

Python

from tilebox.workflows import ExecutionContext
from tilebox.workflows.automations import CronTask

class MyCronTask(CronTask):
    message: str

    def execute(self, context: ExecutionContext) -> None:
        # self.trigger is an attribute of the CronTask class,
        # which contains information about the trigger event
        # that caused this task to be submitted as part of a job
        context.logger.info(
            "Cron task triggered",
            message=self.message,
            trigger_time=self.trigger.time,
        )

Copy

Go

type MyCronTask struct {
    Message string
}

func (t *MyCronTask) Execute(ctx context.Context) error {
    slog.InfoContext(ctx, "Cron task triggered", slog.String("message", t.Message))
    return nil
}

Copy

Registering a cron trigger

After implementing a cron task, register it with one or more schedules. The Python SDK provides a registration helper, and you can also register cron automations from the Tilebox Console. Each matching schedule submits a new job containing one task instance derived from the cron task prototype.

Python

from tilebox.workflows import Client

client = Client()
automations = client.automations()
cron_automation = automations.create_cron_automation(
    "my-cron-automation",  # name of the cron automation
    MyCronTask(message="World"),  # the task (and its input parameters) to run repeatedly
    cron_schedules=[
        "*/15 * * * 1-5",  # every 15 minutes on weekdays in UTC
        "CRON_TZ=Europe/Vienna 0 9 * * 1-5",  # 09:00 on weekdays in Vienna
        "@daily",  # every day at midnight UTC
        "CRON_TZ=Europe/Vienna @daily",  # every day at midnight in Vienna
    ],
)

Copy

Use crontab.guru to check standard five-field expressions. Remove any CRON_TZ=... prefix before entering an expression there.

Cron schedule syntax

Cron triggers accept standard five-field expressions. The fields specify the minute, hour, day of the month, month, and day of the week in that order.

┌───────────── minute (0–59)
│ ┌─────────── hour (0–23)
│ │ ┌───────── day of month (1–31)
│ │ │ ┌─────── month (1–12 or JAN–DEC)
│ │ │ │ ┌───── day of week (0–6 or SUN–SAT; 0 is Sunday)
│ │ │ │ │
* * * * *

Copy

Use * for every value, , for a list, - for a range, and / for a step. For example, */15 * * * * runs every 15 minutes, while 0 9-17 * * 1-5 runs hourly from 09:00 through 17:00 on weekdays.

If both day of month and day of week contain specific values, a trigger runs when either field matches. For example, 0 9 1 * MON runs at 09:00 on the first day of every month and on every Monday.

Schedules without an explicit timezone use UTC. Prefix a schedule with CRON_TZ=<timezone> to interpret it in an IANA timezone:

CRON_TZ=Europe/Vienna 0 9 * * 1-5

Copy

This expression runs at 09:00 Vienna local time on weekdays. The corresponding UTC time changes automatically when Vienna enters or leaves daylight saving time.

Timezone schedules follow traditional cron behavior during daylight saving transitions. A local time skipped when clocks move forward does not trigger. A local time that occurs twice when clocks move backward triggers twice.

Schedule helpers

You can replace a five-field expression with one of these helpers. Helpers use UTC unless you add a CRON_TZ prefix.

Helper	Cron expression	Meaning
@yearly or @annually	0 0 1 1 *	At midnight on January 1
@monthly	0 0 1 * *	At midnight on the first day of each month
@weekly	0 0 * * 0	At midnight every Sunday
@daily or @midnight	0 0 * * *	At midnight every day
@hourly	0 * * * *	At the start of every hour

Timezone prefixes also work with helpers:

CRON_TZ=Europe/Vienna @daily

Copy

This schedule runs every day at midnight in Vienna.

Schedule examples

Schedule	Meaning
0 * * * *	At the start of every hour in UTC
*/15 * * * *	Every 15 minutes in UTC
30 13 * * 3	Every Wednesday at 13:30 UTC
0 9 1 * MON	At 09:00 UTC on every Monday and every first day of the month
CRON_TZ=Europe/Vienna 0 9 * * 1-5	At 09:00 Vienna time on weekdays
@daily	Every day at midnight UTC
CRON_TZ=Europe/Vienna @daily	Every day at midnight in Vienna
@weekly	Every Sunday at midnight UTC

Starting a cron runner

Cron tasks run on any regular runner that has the task registered. Keep at least one such runner available to execute jobs submitted by the automation.

Python

from tilebox.workflows import Client, Runner

client = Client()
runner = Runner(tasks=[MyCronTask])
runner.connect_to(client).run_forever()

Copy

If this runner runs continuously, its logs may resemble the following:

Logs

Cron task triggered message=World trigger_time=2023-09-25 16:12:00
Cron task triggered message=World trigger_time=2023-09-25 17:12:00
Cron task triggered message=World trigger_time=2023-09-25 18:12:00
Cron task triggered message=World trigger_time=2023-09-25 18:45:00
Cron task triggered message=World trigger_time=2023-09-25 19:12:00

Copy

Inspecting in the Console

The Tilebox Console provides a straightforward way to inspect all registered Cron automations.

Use the console to view, edit, and delete the registered Cron automations.

You can also inspect registered cron triggers from the SDKs.

Python

from tilebox.workflows import Client

client = Client()
automations = client.automations().all()

for automation in automations:
    for trigger in automation.cron_triggers:
        print(automation.name, trigger.schedule)

Copy

Go

ctx := context.Background()
client := workflows.NewClient()

automations, err := client.Automations.List(ctx)
if err != nil {
    slog.ErrorContext(ctx, "failed to list automations", slog.Any("error", err))
    return
}

for _, automation := range automations {
    for _, trigger := range automation.CronTriggers {
        slog.InfoContext(ctx,
            "cron trigger",
            slog.String("automation", automation.Name),
            slog.String("schedule", trigger.Schedule),
        )
    }
}

Copy

Deleting Cron automations

To delete a registered Cron automation from Python, use automations.delete. You can also delete cron automations from the Tilebox Console. After deletion, no new jobs will be submitted by that Cron trigger. Past jobs already triggered will still remain queued.

Python

from tilebox.workflows import Client

client = Client()
automations = client.automations()

# delete the automation as returned by create_cron_automation
automations.delete(cron_automation)

# or manually by id:
automations.delete("0190bafc-b3b8-88c4-008b-a5db044380d0")

Copy

Submitting Cron jobs manually

In Python, you can submit Cron tasks as regular tasks for testing purposes or as part of a larger workflow. To do so, instantiate the task with a specific trigger time using the once method.

Submitting a job with a Cron task using once immediately schedules the task, and a runner may pick it up and execute it. The trigger time set in the once method does not influence the execution time; it only sets the self.trigger.time attribute for the Cron task.

Python

from datetime import datetime, timezone

job_client = client.jobs()

# create a Cron task prototype
task = MyCronTask(message="Hello")

# submitting it directly won't work: raises ValueError:
# job_client.submit("manual-cron-job", task)

# instead trigger a cron task with the current time as the trigger time
job_client.submit("manual-cron-job", task.once())

# or specify a trigger time in the past or future
# irrespective of the trigger time, the task will always be scheduled to run immediately
job_client.submit(
    "manual-cron-job", 
    task.once(datetime(2030, 12, 12, 15, 15, tzinfo=timezone.utc))
)

Copy