============================ Configuration and defaults ============================ This document describes the configuration options available. If you're using celery in a Django project these settings should be defined in the project's ``settings.py`` file. In a regular Python environment, that is using the default loader, you must create the ``celeryconfig.py`` module and make sure it is available on the Python path. Example configuration file ========================== This is an example configuration file to get you started. It should contain all you need to run a basic celery set-up. .. code-block:: python CELERY_RESULT_BACKEND = "database" DATABASE_ENGINE = "sqlite3" DATABASE_NAME = "mydatabase.db" BROKER_HOST = "localhost" BROKER_PORT = 5672 BROKER_VHOST = "/" BROKER_USER = "guest" BROKER_PASSWORD = "guest" ## If you're doing mostly I/O you can have more processes, ## but if mostly spending CPU, try to keep it close to the ## number of CPUs on your machine. If not set, the number of CPUs/cores ## available will be used. # CELERYD_CONCURRENCY = 8 # CELERYD_LOG_FILE = "celeryd.log" # CELERYD_LOG_LEVEL = "INFO" Concurrency settings ==================== * CELERYD_CONCURRENCY The number of concurrent worker processes, executing tasks simultaneously. Defaults to the number of CPUs/cores available. * CELERYD_PREFETCH_MULTIPLIER How many messages to prefetch at a time multiplied by the number of concurrent processes. The default is 4 (four messages for each process). The default setting seems pretty good here. However, if you have very long running tasks waiting in the queue and you have to start the workers, note that the first worker to start will receive four times the number of messages initially. Thus the tasks may not be fairly balanced among the workers. Task result backend settings ============================ * CELERY_RESULT_BACKEND The backend used to store task results (tombstones). Can be one of the following: * database (default) Use a relational database supported by the Django ORM. * cache Use `memcached`_ to store the results. * mongodb Use `MongoDB`_ to store the results. * redis Use `Redis`_ to store the results. * tyrant Use `Tokyo Tyrant`_ to store the results. * amqp Send results back as AMQP messages (**WARNING** While very fast, you must make sure you only receive the result once. See :doc:`userguide/executing`). .. _`memcached`: http://memcached.org .. _`MongoDB`: http://mongodb.org .. _`Redis`: http://code.google.com/p/redis/ .. _`Tokyo Tyrant`: http://1978th.net/tokyotyrant/ Database backend settings ========================= Please see the Django ORM database settings documentation: http://docs.djangoproject.com/en/dev/ref/settings/#database-engine If you use this backend, make sure to initialize the database tables after configuration. When using celery with a Django project this means executing:: $ python manage.py syncdb When using celery in a regular Python environment you have to execute:: $ celeryinit Example configuration --------------------- .. code-block:: python CELERY_RESULT_BACKEND = "database" DATABASE_ENGINE = "mysql" DATABASE_USER = "myusername" DATABASE_PASSWORD = "mypassword" DATABASE_NAME = "mydatabase" DATABASE_HOST = "localhost" AMQP backend settings ===================== The AMQP backend does not have any settings yet. Example configuration --------------------- CELERY_RESULT_BACKEND = "amqp" Cache backend settings ====================== Please see the documentation for the Django cache framework settings: http://docs.djangoproject.com/en/dev/topics/cache/#memcached To use a custom cache backend for Celery, while using another for Django, you should use the ``CELERY_CACHE_BACKEND`` setting instead of the regular django ``CACHE_BACKEND`` setting. Example configuration --------------------- Using a single memcached server: .. code-block:: python CACHE_BACKEND = 'memcached://127.0.0.1:11211/' Using multiple memcached servers: .. code-block:: python CELERY_RESULT_BACKEND = "cache" CACHE_BACKEND = 'memcached://172.19.26.240:11211;172.19.26.242:11211/' Tokyo Tyrant backend settings ============================= **NOTE** The Tokyo Tyrant backend requires the :mod:`pytyrant` library: http://pypi.python.org/pypi/pytyrant/ This backend requires the following configuration directives to be set: * TT_HOST Hostname of the Tokyo Tyrant server. * TT_PORT The port the Tokyo Tyrant server is listening to. Example configuration --------------------- .. code-block:: python CELERY_RESULT_BACKEND = "tyrant" TT_HOST = "localhost" TT_PORT = 1978 Redis backend settings ====================== **NOTE** The Redis backend requires the :mod:`redis` library: http://pypi.python.org/pypi/redis/0.5.5 To install the redis package use ``pip`` or ``easy_install``:: $ pip install redis This backend requires the following configuration directives to be set: * REDIS_HOST Hostname of the Redis database server. e.g. ``"localhost"``. * REDIS_PORT Port to the Redis database server. e.g. ``6379``. Also, the following optional configuration directives are available: * REDIS_DB Name of the database to use. Default is ``celery_results``. * REDIS_PASSWORD Password used to connect to the database. Example configuration --------------------- .. code-block:: python CELERY_RESULT_BACKEND = "redis" REDIS_HOST = "localhost" REDIS_PORT = 6379 REDIS_DATABASE = "celery_results" REDIS_CONNECT_RETRY=True MongoDB backend settings ======================== **NOTE** The MongoDB backend requires the :mod:`pymongo` library: http://github.com/mongodb/mongo-python-driver/tree/master * CELERY_MONGODB_BACKEND_SETTINGS This is a dict supporting the following keys: * host Hostname of the MongoDB server. Defaults to "localhost". * port The port the MongoDB server is listening to. Defaults to 27017. * user User name to authenticate to the MongoDB server as (optional). * password Password to authenticate to the MongoDB server (optional). * database The database name to connect to. Defaults to "celery". * taskmeta_collection The collection name to store task meta data. Defaults to "celery_taskmeta". Example configuration --------------------- .. code-block:: python CELERY_RESULT_BACKEND = "mongodb" CELERY_MONGODB_BACKEND_SETTINGS = { "host": "192.168.1.100", "port": 30000, "database": "mydb", "taskmeta_collection": "my_taskmeta_collection", } Messaging settings ================== Routing ------- * CELERY_QUEUES The mapping of queues the worker consumes from. This is a dictionary of queue name/options. See :doc:`userguide/routing` for more information. The default is a queue/exchange/binding key of ``"celery"``, with exchange type ``direct``. You don't have to care about this unless you want custom routing facilities. * CELERY_DEFAULT_QUEUE The queue used by default, if no custom queue is specified. This queue must be listed in ``CELERY_QUEUES``. The default is: ``celery``. * CELERY_DEFAULT_EXCHANGE Name of the default exchange to use when no custom exchange is specified. The default is: ``celery``. * CELERY_DEFAULT_EXCHANGE_TYPE Default exchange type used when no custom exchange is specified. The default is: ``direct``. * CELERY_DEFAULT_ROUTING_KEY The default routing key used when sending tasks. The default is: ``celery``. Connection ---------- * CELERY_BROKER_CONNECTION_TIMEOUT The timeout in seconds before we give up establishing a connection to the AMQP server. Default is 4 seconds. * CELERY_BROKER_CONNECTION_RETRY Automatically try to re-establish the connection to the AMQP broker if it's lost. The time between retries is increased for each retry, and is not exhausted before ``CELERY_BROKER_CONNECTION_MAX_RETRIES`` is exceeded. This behavior is on by default. * CELERY_BROKER_CONNECTION_MAX_RETRIES Maximum number of retries before we give up re-establishing a connection to the AMQP broker. If this is set to ``0`` or ``None``, we will retry forever. Default is 100 retries. Task execution settings ======================= * CELERY_ALWAYS_EAGER If this is ``True``, all tasks will be executed locally by blocking until it is finished. ``apply_async`` and ``Task.delay`` will return a :class:`celery.result.EagerResult` which emulates the behavior of :class:`celery.result.AsyncResult`, except the result has already been evaluated. Tasks will never be sent to the queue, but executed locally instead. * CELERY_IGNORE_RESULT Whether to store the task return values or not (tombstones). If you still want to store errors, just not successful return values, you can set ``CELERY_STORE_ERRORS_EVEN_IF_IGNORED``. * CELERY_TASK_RESULT_EXPIRES Time (in seconds, or a :class:`datetime.timedelta` object) for when after stored task tombstones are deleted. **NOTE**: For the moment this only works with the database, cache and MongoDB * CELERY_TRACK_STARTED If ``True`` the task will report its status as "started" when the task is executed by a worker. The default value is ``False`` as the normal behaviour is to not report that level of granularity. Tasks are either pending, finished, or waiting to be retried. Having a "started" status can be useful for when there are long running tasks and there is a need to report which task is currently running. backends. * CELERY_TASK_SERIALIZER A string identifying the default serialization method to use. Can be ``pickle`` (default), ``json``, ``yaml``, or any custom serialization methods that have been registered with :mod:`carrot.serialization.registry`. Default is ``pickle``. * CELERY_DEFAULT_RATE_LIMIT The global default rate limit for tasks. This value is used for tasks that does not have a custom rate limit The default is no rate limit. * CELERY_DISABLE_RATE_LIMITS Disable all rate limits, even if tasks has explicit rate limits set. Worker: celeryd =============== * CELERY_IMPORTS A sequence of modules to import when the celery daemon starts. This is useful to add tasks if you are not using django or cannot use task auto-discovery. * CELERY_SEND_EVENTS Send events so the worker can be monitored by tools like ``celerymon``. * CELERY_SEND_TASK_ERROR_EMAILS If set to ``True``, errors in tasks will be sent to admins by e-mail. If unset, it will send the e-mails if ``settings.DEBUG`` is False. * CELERY_STORE_ERRORS_EVEN_IF_IGNORED If set, the worker stores all task errors in the result store even if ``Task.ignore_result`` is on. Logging ------- * CELERYD_LOG_FILE The default file name the worker daemon logs messages to, can be overridden using the `--logfile`` option to ``celeryd``. The default is ``None`` (``stderr``) Can also be set via the ``--logfile`` argument. * CELERYD_LOG_LEVEL Worker log level, can be any of ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR``, ``CRITICAL``. Can also be set via the ``--loglevel`` argument. See the :mod:`logging` module for more information. * CELERYD_LOG_FORMAT The format to use for log messages. Can be overridden using the ``--loglevel`` option to ``celeryd``. Default is ``[%(asctime)s: %(levelname)s/%(processName)s] %(message)s`` See the Python :mod:`logging` module for more information about log formats. Periodic Task Server: celerybeat ================================ * CELERYBEAT_SCHEDULE_FILENAME Name of the file celerybeat stores the current schedule in. Can be a relative or absolute path, but be aware that the suffix ``.db`` will be appended to the file name. Can also be set via the ``--schedule`` argument. * CELERYBEAT_MAX_LOOP_INTERVAL The maximum number of seconds celerybeat can sleep between checking the schedule. Default is 300 seconds (5 minutes). * CELERYBEAT_LOG_FILE The default file name to log messages to, can be overridden using the `--logfile`` option. The default is ``None`` (``stderr``). Can also be set via the ``--logfile`` argument. * CELERYBEAT_LOG_LEVEL Logging level. Can be any of ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR``, or ``CRITICAL``. Can also be set via the ``--loglevel`` argument. See the :mod:`logging` module for more information. Monitor Server: celerymon ========================= * CELERYMON_LOG_FILE The default file name to log messages to, can be overridden using the `--logfile`` option. The default is ``None`` (``stderr``) Can also be set via the ``--logfile`` argument. * CELERYMON_LOG_LEVEL Logging level. Can be any of ``DEBUG``, ``INFO``, ``WARNING``, ``ERROR``, or ``CRITICAL``. See the :mod:`logging` module for more information.