python - How to dynamically add a scheduled task to Celery beat

Python - How to dynamically add a scheduled task to Celery beat

To dynamically add a scheduled task to Celery Beat in Python, you can follow these steps. Celery Beat allows you to define periodic tasks (also known as cron jobs) using the Celery scheduler. Dynamically adding tasks means that you can add tasks at runtime based on certain conditions or user inputs.

Here's a structured approach to achieve this:

Step-by-Step Approach

  1. Define your Celery Task:

    First, define the task you want to schedule. This is a standard Celery task with a @celery.task decorator.

    # tasks.py from celery import Celery celery = Celery('tasks', broker='redis://localhost:6379/0') @celery.task def my_task(arg1, arg2): # Task logic here print(f"Executing task with arguments: {arg1}, {arg2}")

  2. Access the Celery Beat Scheduler:

    Celery Beat uses a scheduler to manage periodic tasks. To dynamically add tasks, you need to interact with this scheduler.

    from celery import Celery from celery.schedules import crontab app = Celery('tasks', broker='redis://localhost:6379/0') # Function to add a new periodic task def add_periodic_task(task_name, schedule, task_args): app.conf.beat_schedule[task_name] = { 'task': 'tasks.my_task', 'schedule': schedule, 'args': task_args } app.conf.timezone = 'UTC'

  3. Add a New Periodic Task Dynamically:

    Use the add_periodic_task function to add tasks dynamically. Adjust the parameters (task_name, schedule, task_args) as per your requirements.

    if __name__ == '__main__': # Example of dynamically adding a task task_name = 'my_periodic_task' schedule = crontab(minute='*/15') # Runs every 15 minutes task_args = (1, 2) # Arguments for my_task add_periodic_task(task_name, schedule, task_args)

  4. Start Celery Beat:

    Ensure Celery Beat is running to schedule and execute the tasks.

    celery -A tasks beat

Explanation:

  • Celery Configuration (app.conf.beat_schedule): app.conf.beat_schedule is a dictionary where you define your periodic tasks. Each task is specified by a unique task_name (string), a schedule (using crontab or other schedules from celery.schedules), and task_args (tuple of arguments for your task function).

  • Dynamic Task Addition (add_periodic_task): The add_periodic_task function allows you to add new tasks dynamically by updating app.conf.beat_schedule with the task details.

  • Starting Celery Beat: Make sure Celery Beat is started separately from Celery workers (celery -A tasks beat). Celery Beat manages the periodic task schedule and sends tasks to the Celery worker for execution.

Notes:

  • Persistence: Changes made to app.conf.beat_schedule are not persistent unless you configure a result backend for Celery Beat to store its schedule state.

  • Dynamic Modifications: You can modify existing tasks or remove them dynamically by manipulating app.conf.beat_schedule.

  • Concurrency: Ensure that modifications to app.conf.beat_schedule are handled carefully in concurrent environments to avoid race conditions.

By following these steps, you can dynamically add scheduled tasks to Celery Beat in Python, enabling your application to adapt to changing requirements or conditions at runtime. Adjust the task names, schedules, and arguments to fit your specific use case and scheduling needs.

Examples

  1. Python Celery dynamically add periodic task to Celery beat

    • Description: Dynamically add a recurring task to Celery beat scheduler programmatically.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Dynamically add a periodic task to Celery beat schedule = crontab(hour=10, minute=30, day_of_week='mon-fri') app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, } print("Scheduled task 'my_task' to run daily at 10:30 AM (Monday to Friday).")

  2. Python Celery add scheduled task at runtime

    • Description: Add a new task with a specific schedule to Celery beat dynamically during runtime.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Define a function to add a new periodic task dynamically def add_periodic_task(task_name, schedule): app.conf.beat_schedule[task_name] = { 'task': task_name, 'schedule': schedule, } print(f"Added periodic task '{task_name}' with schedule {schedule}.") # Example usage: Add a task that runs every 2 hours schedule = crontab(minute=0, hour='*/2') add_periodic_task('my_task', schedule)

  3. Python Celery schedule task dynamically with custom interval

    • Description: Dynamically add a task to Celery beat with a custom interval (e.g., every 5 minutes).
    • Code:
      from celery import Celery from celery.schedules import schedule app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Dynamically add a periodic task with custom interval schedule = schedule(run_every=300) # 300 seconds = 5 minutes app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, } print("Scheduled task 'my_task' to run every 5 minutes.")

  4. Python Celery add recurring task programmatically

    • Description: Programatically add a recurring task to Celery beat scheduler with a specific schedule.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Add a recurring task programmatically schedule = crontab(minute=0, hour='*/3') # Every 3 hours app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, } print("Scheduled task 'my_task' to run every 3 hours.")

  5. Python Celery dynamically add periodic task with arguments

    • Description: Add a periodic task to Celery beat scheduler with dynamic arguments.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function with arguments @app.task def my_task(arg1, arg2): print(f"Executing my_task with arguments: {arg1}, {arg2}.") # Function to dynamically add a periodic task with arguments def add_periodic_task_with_args(task_name, schedule, args): app.conf.beat_schedule[task_name] = { 'task': task_name, 'schedule': schedule, 'args': args, } print(f"Added periodic task '{task_name}' with schedule {schedule} and arguments {args}.") # Example usage: Add a task that runs daily with arguments schedule = crontab(hour=10, minute=30) task_args = ('arg1_value', 'arg2_value') add_periodic_task_with_args('my_task', schedule, task_args)

  6. Python Celery schedule task dynamically based on external input

    • Description: Schedule a task dynamically in Celery beat based on parameters or external input.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Function to dynamically schedule task based on external input def schedule_task(task_name, schedule_params): schedule = crontab(**schedule_params) app.conf.beat_schedule[task_name] = { 'task': task_name, 'schedule': schedule, } print(f"Scheduled task '{task_name}' with schedule {schedule_params}.") # Example usage: Schedule a task based on specific parameters schedule_params = {'hour': 10, 'minute': 30, 'day_of_week': 'mon-fri'} schedule_task('my_task', schedule_params)

  7. Python Celery add periodic task with timezone

    • Description: Add a periodic task to Celery beat scheduler with a specific timezone.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Add a periodic task with timezone schedule = crontab(hour=10, minute=30, day_of_week='mon-fri', timezone='Europe/Berlin') app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, } print("Scheduled task 'my_task' to run daily at 10:30 AM (Monday to Friday) in Europe/Berlin timezone.")

  8. Python Celery dynamically add task with fixed interval

    • Description: Dynamically add a task to Celery beat with a fixed interval (e.g., every 10 minutes).
    • Code:
      from celery import Celery from datetime import timedelta app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Dynamically add a periodic task with fixed interval app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': timedelta(minutes=10), } print("Scheduled task 'my_task' to run every 10 minutes.")

  9. Python Celery add periodic task with start time

    • Description: Add a periodic task to Celery beat scheduler with a specific start time.
    • Code:
      from celery import Celery from celery.schedules import crontab app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Add a periodic task with start time schedule = crontab(hour=10, minute=30, day_of_week='mon-fri') app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, 'args': (), 'kwargs': {}, 'options': {'expires': 10}, } print("Scheduled task 'my_task' at 10:30 AM (Monday to Friday).")

  10. Python Celery dynamically add task with custom schedule

    • Description: Dynamically add a task to Celery beat with a custom schedule (e.g., every 5 seconds).
    • Code:
      from celery import Celery from celery.schedules import schedule app = Celery() # Define the task function @app.task def my_task(): print("Executing my_task...") # Dynamically add a periodic task with custom schedule schedule = schedule(run_every=5) app.conf.beat_schedule['my_task'] = { 'task': 'my_task', 'schedule': schedule, } print("Scheduled task 'my_task' to run every 5 seconds.")

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