This document describes the current stable version of Celery (5.2). For development docs, go here.

celery.contrib.migrate

Message migration tools (Broker <-> Broker).

class celery.contrib.migrate.State

Migration progress state.

count = 0

filtered = 0

property strtotal

total_apx = 0

exception celery.contrib.migrate.StopFiltering

Semi-predicate used to signal filter stop.

celery.contrib.migrate.migrate_task(producer, body_, message, queues=None)

Migrate single task message.

celery.contrib.migrate.migrate_tasks(source, dest, migrate=<function migrate_task>, app=None, queues=None, **kwargs)

Migrate tasks from one broker to another.

celery.contrib.migrate.move(predicate, connection=None, exchange=None, routing_key=None, source=None, app=None, callback=None, limit=None, transform=None, **kwargs)

Find tasks by filtering them and move the tasks to a new queue.

Parameters:

• predicate (Callable) –

  Filter function used to decide the messages to move. Must accept the standard signature of (body, message) used by Kombu consumer callbacks. If the predicate wants the message to be moved it must return either:

  1. a tuple of (exchange, routing_key), or

  2. a Queue instance, or

  3. any other true value means the specified

     exchange and routing_key arguments will be used.

• connection (kombu.Connection) – Custom connection to use.

• source – List[Union[str, kombu.Queue]]: Optional list of source queues to use instead of the default (queues in task_queues). This list can also contain Queue instances.

• exchange (str, kombu.Exchange) – Default destination exchange.

• routing_key (str) – Default destination routing key.

• limit (int) – Limit number of messages to filter.

• callback (Callable) – Callback called after message moved, with signature (state, body, message).

• transform (Callable) – Optional function to transform the return value (destination) of the filter function.

Also supports the same keyword arguments as start_filter().

To demonstrate, the move_task_by_id() operation can be implemented like this:

def is_wanted_task(body, message):
    if body['id'] == wanted_id:
        return Queue('foo', exchange=Exchange('foo'),
                     routing_key='foo')

move(is_wanted_task)

or with a transform:

def transform(value):
    if isinstance(value, str):
        return Queue(value, Exchange(value), value)
    return value

move(is_wanted_task, transform=transform)

Note

The predicate may also return a tuple of (exchange, routing_key) to specify the destination to where the task should be moved, or a Queue instance. Any other true value means that the task will be moved to the default exchange/routing_key.

celery.contrib.migrate.move_by_idmap(map, **kwargs)

Move tasks by matching from a task_id: queue mapping.

Where queue is a queue to move the task to.

Example

>>> move_by_idmap({
...     '5bee6e82-f4ac-468e-bd3d-13e8600250bc': Queue('name'),
...     'ada8652d-aef3-466b-abd2-becdaf1b82b3': Queue('name'),
...     '3a2b140d-7db1-41ba-ac90-c36a0ef4ab1f': Queue('name')},
...   queues=['hipri'])

celery.contrib.migrate.move_by_taskmap(map, **kwargs)

Move tasks by matching from a task_name: queue mapping.

queue is the queue to move the task to.

Example

>>> move_by_taskmap({
...     'tasks.add': Queue('name'),
...     'tasks.mul': Queue('name'),
... })

celery.contrib.migrate.move_direct(predicate, connection=None, exchange=None, routing_key=None, source=None, app=None, callback=None, limit=None, *, transform=<function worker_direct>, **kwargs)

Find tasks by filtering them and move the tasks to a new queue.

Parameters:

• predicate (Callable) –

  Filter function used to decide the messages to move. Must accept the standard signature of (body, message) used by Kombu consumer callbacks. If the predicate wants the message to be moved it must return either:

  1. a tuple of (exchange, routing_key), or

  2. a Queue instance, or

  3. any other true value means the specified

     exchange and routing_key arguments will be used.

• connection (kombu.Connection) – Custom connection to use.

• source – List[Union[str, kombu.Queue]]: Optional list of source queues to use instead of the default (queues in task_queues). This list can also contain Queue instances.

• exchange (str, kombu.Exchange) – Default destination exchange.

• routing_key (str) – Default destination routing key.

• limit (int) – Limit number of messages to filter.

• callback (Callable) – Callback called after message moved, with signature (state, body, message).

• transform (Callable) – Optional function to transform the return value (destination) of the filter function.

Also supports the same keyword arguments as start_filter().

To demonstrate, the move_task_by_id() operation can be implemented like this:

def is_wanted_task(body, message):
    if body['id'] == wanted_id:
        return Queue('foo', exchange=Exchange('foo'),
                     routing_key='foo')

move(is_wanted_task)

or with a transform:

def transform(value):
    if isinstance(value, str):
        return Queue(value, Exchange(value), value)
    return value

move(is_wanted_task, transform=transform)

Note

The predicate may also return a tuple of (exchange, routing_key) to specify the destination to where the task should be moved, or a Queue instance. Any other true value means that the task will be moved to the default exchange/routing_key.

celery.contrib.migrate.move_direct_by_id(task_id, dest, **kwargs)

Find a task by id and move it to another queue.

Parameters:

• task_id (str) – Id of task to find and move.

• dest – (str, kombu.Queue): Destination queue.

• transform (Callable) – Optional function to transform the return value (destination) of the filter function.

• **kwargs (Any) – Also supports the same keyword arguments as move().

celery.contrib.migrate.move_task_by_id(task_id, dest, **kwargs)

Find a task by id and move it to another queue.

Parameters:

• task_id (str) – Id of task to find and move.

• dest – (str, kombu.Queue): Destination queue.

• transform (Callable) – Optional function to transform the return value (destination) of the filter function.

• **kwargs (Any) – Also supports the same keyword arguments as move().

celery.contrib.migrate.republish(producer, message, exchange=None, routing_key=None, remove_props=None)

Republish message.

celery.contrib.migrate.start_filter(app, conn, filter, limit=None, timeout=1.0, ack_messages=False, tasks=None, queues=None, callback=None, forever=False, on_declare_queue=None, consume_from=None, state=None, accept=None, **kwargs)

Filter tasks.

celery.contrib.migrate.task_id_eq(task_id, body, message)

Return true if task id equals task_id’.

celery.contrib.migrate.task_id_in(ids, body, message)

Return true if task id is member of set ids’.