Configuration¶

Broker¶

app.config_from_object({
    # Valkey/Redis
    "broker_url": "redis://localhost:6379/0",  # or valkey://

    # RabbitMQ (AMQP)
    # "broker_url": "amqp://guest:guest@localhost:5672//",
})

Result backend¶

app.config_from_object({
    "result_backend": "redis://localhost:6379/1",
})

Without a result backend, task return values are discarded. Set result_extended = True to store extra metadata (task name, args, kwargs, worker hostname).

Worker settings¶

Setting	Default	Description
`worker_concurrency`	CPU count	Total task concurrency
`worker_max_tasks_per_child`	None	Restart worker after N tasks
`worker_max_memory_per_child`	None	Restart worker if RSS exceeds N KiB
`task_soft_time_limit`	None	Soft time limit in seconds
`task_time_limit`	None	Hard time limit in seconds
`task_acks_late`	False	Acknowledge tasks after execution

Serialization¶

app.config_from_object({
    "task_serializer": "json",       # json, pickle, msgpack, yaml
    "result_serializer": "json",
    "accept_content": ["json"],
})

Task autodiscovery¶

app = Celery("myapp")
app.config_from_object({
    "include": ["myapp.tasks", "myapp.other_tasks"],
})

Or with Django:

app.autodiscover_tasks()

CLI options¶

celery -A app worker [OPTIONS]

Options:
  --loglevel=INFO          Log level (DEBUG, INFO, WARNING, ERROR)
  -E / --task-events       Enable task events for Flower
  --loop-workers=N         Number of async loop workers (default: 1)
  --loop-concurrency=N     Max concurrent async tasks per loop worker (default: 10)
  --sync-workers=N         Number of sync worker threads (default: 1)
  --max-tasks-per-child=N  Restart after N tasks
  --max-memory-per-child=N Restart if RSS exceeds N KiB