This document describes the current stable version of Celery (5.3). For development docs, go here.

Source code for celery.app.backends

"""Backend selection."""
import sys
import types

from celery._state import current_app
from celery.exceptions import ImproperlyConfigured, reraise
from celery.utils.imports import load_extension_class_names, symbol_by_name

__all__ = ('by_name', 'by_url')

UNKNOWN_BACKEND = """
Unknown result backend: {0!r}.  Did you spell that correctly? ({1!r})
"""

BACKEND_ALIASES = {
    'amqp': 'celery.backends.amqp:AMQPBackend',
    'rpc': 'celery.backends.rpc.RPCBackend',
    'cache': 'celery.backends.cache:CacheBackend',
    'redis': 'celery.backends.redis:RedisBackend',
    'rediss': 'celery.backends.redis:RedisBackend',
    'sentinel': 'celery.backends.redis:SentinelBackend',
    'mongodb': 'celery.backends.mongodb:MongoBackend',
    'db': 'celery.backends.database:DatabaseBackend',
    'database': 'celery.backends.database:DatabaseBackend',
    'elasticsearch': 'celery.backends.elasticsearch:ElasticsearchBackend',
    'cassandra': 'celery.backends.cassandra:CassandraBackend',
    'couchbase': 'celery.backends.couchbase:CouchbaseBackend',
    'couchdb': 'celery.backends.couchdb:CouchBackend',
    'cosmosdbsql': 'celery.backends.cosmosdbsql:CosmosDBSQLBackend',
    'riak': 'celery.backends.riak:RiakBackend',
    'file': 'celery.backends.filesystem:FilesystemBackend',
    'disabled': 'celery.backends.base:DisabledBackend',
    'consul': 'celery.backends.consul:ConsulBackend',
    'dynamodb': 'celery.backends.dynamodb:DynamoDBBackend',
    'azureblockblob': 'celery.backends.azureblockblob:AzureBlockBlobBackend',
    'arangodb': 'celery.backends.arangodb:ArangoDbBackend',
    's3': 'celery.backends.s3:S3Backend',
}


[docs]def by_name(backend=None, loader=None, extension_namespace='celery.result_backends'): """Get backend class by name/alias.""" backend = backend or 'disabled' loader = loader or current_app.loader aliases = dict(BACKEND_ALIASES, **loader.override_backends) aliases.update(load_extension_class_names(extension_namespace)) try: cls = symbol_by_name(backend, aliases) except ValueError as exc: reraise(ImproperlyConfigured, ImproperlyConfigured( UNKNOWN_BACKEND.strip().format(backend, exc)), sys.exc_info()[2]) if isinstance(cls, types.ModuleType): raise ImproperlyConfigured(UNKNOWN_BACKEND.strip().format( backend, 'is a Python module, not a backend class.')) return cls
[docs]def by_url(backend=None, loader=None): """Get backend class by URL.""" url = None if backend and '://' in backend: url = backend scheme, _, _ = url.partition('://') if '+' in scheme: backend, url = url.split('+', 1) else: backend = scheme return by_name(backend, loader), url