============================ Configuration and defaults ============================ This document describes the configuration options available. If you're using the default loader, you must create the ``celeryconfig.py`` module and make sure it is available on the Python path. .. contents:: :local: 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 # List of modules to import when celery starts. CELERY_IMPORTS = ("myapp.tasks", ) ## Result store settings. CELERY_RESULT_BACKEND = "database" CELERY_RESULT_DBURI = "sqlite:///mydatabase.db" ## Broker settings. BROKER_HOST = "localhost" BROKER_PORT = 5672 BROKER_VHOST = "/" BROKER_USER = "guest" BROKER_PASSWORD = "guest" ## Worker settings ## 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 = 10 # 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 `SQLAlchemy`_. * 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`). .. _`SQLAlchemy`: http://sqlalchemy.org .. _`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 `Supported Databases`_ for a table of supported databases. To use this backend you need to configure it with an `Connection String`_, some examples include: .. code-block:: python # sqlite (filename) CELERY_RESULT_DBURI = "sqlite:///celerydb.sqlite" # mysql CELERY_RESULT_DBURI = "mysql://scott:tiger@localhost/foo" # postgresql CELERY_RESULT_DBURI = "postgresql://scott:tiger@localhost/mydatabase" # oracle CELERY_RESULT_DBURI = "oracle://scott:tiger@127.0.0.1:1521/sidname" See `Connection String`_ for more information about connection strings. To specify additional SQLAlchemy database engine options you can use the ``CELERY_RESULT_ENGINE_OPTIONS`` setting:: # echo enables verbose logging from SQLAlchemy. CELERY_RESULT_ENGINE_OPTIONS = {"echo": True} .. _`Supported Databases`: http://www.sqlalchemy.org/docs/dbengine.html#supported-databases .. _`Connection String`: http://www.sqlalchemy.org/docs/dbengine.html#create-engine-url-arguments Example configuration --------------------- .. code-block:: python CELERY_RESULT_BACKEND = "database" CELERY_RESULT_DBURI = "mysql://user:password@host/dbname" AMQP backend settings ===================== * CELERY_RESULT_EXCHANGE Name of the exchange to publish results in. Default is ``"celeryresults"``. * CELERY_RESULT_EXCHANGE_TYPE The exchange type of the result exchange. Default is to use a ``direct`` exchange. * CELERY_RESULT_SERIALIZER Result message serialization format. Default is ``"pickle"``. * CELERY_RESULTS_PERSISTENT If set to ``True``, result messages will be persistent. This means the messages will not be lost after a broker restart. The default is for the results to be transient. Example configuration --------------------- CELERY_RESULT_BACKEND = "amqp" Cache backend settings ====================== The cache backend supports the `pylibmc`_ and `python-memcached` libraries. The latter is used only if `pylibmc`_ is not installed. Example configuration --------------------- Using a single memcached server: .. code-block:: python CELERY_CACHE_BACKEND = 'memcached://127.0.0.1:11211/' Using multiple memcached servers: .. code-block:: python CELERY_RESULT_BACKEND = "cache" CELERY_CACHE_BACKEND = 'memcached://172.19.26.240:11211;172.19.26.242:11211/' You can set pylibmc options using the ``CELERY_CACHE_BACKEND_OPTIONS`` setting: .. code-block:: python CELERY_CACHE_BACKEND_OPTIONS = {"binary": True, "behaviors": {"tcp_nodelay": True}} .. _`pylibmc`: http://sendapatch.se/projects/pylibmc/ 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 Database number to use. Default is 0 * 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_DB = "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``. * CELERY_DEFAULT_DELIVERY_MODE Can be ``transient`` or ``persistent``. Default is to send persistent messages. 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_EAGER_PROPAGATES_EXCEPTIONS If this is ``True``, eagerly executed tasks (using ``.apply``, or with ``CELERY_ALWAYS_EAGER`` on), will raise exceptions. It's the same as always running ``apply`` with ``throw=True``. * 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 will be deleted. A built-in periodic task will delete the results after this time (:class:`celery.task.builtins.DeleteExpiredTaskMetaTask`). **NOTE**: For the moment this only works with the database, cache and MongoDB backends. **NOTE**: ``celerybeat`` must be running for the results to be expired. * CELERY_MAX_CACHED_RESULTS Total number of results to store before results are evicted from the result cache. The default is ``5000``. * 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. * CELERY_ACKS_LATE Late ack means the task messages will be acknowledged **after** the task has been executed, not *just before*, which is the default behavior. See http://ask.github.com/celery/faq.html#should-i-use-retry-or-acks-late Worker: celeryd =============== * CELERY_IMPORTS A sequence of modules to import when the celery daemon starts. This is used to specify the task modules to import, but also to import signal handlers and additional remote control commands, etc. * CELERYD_MAX_TASKS_PER_CHILD Maximum number of tasks a pool worker process can execute before it's replaced with a new one. Default is no limit. * CELERYD_TASK_TIME_LIMIT Task hard time limit in seconds. The worker processing the task will be killed and replaced with a new one when this is exceeded. * CELERYD_SOFT_TASK_TIME_LIMIT Task soft time limit in seconds. The :exc:`celery.exceptions.SoftTimeLimitExceeded` exception will be raised when this is exceeded. The task can catch this to e.g. clean up before the hard time limit comes. .. code-block:: python from celery.decorators import task from celery.exceptions import SoftTimeLimitExceeded @task() def mytask(): try: return do_work() except SoftTimeLimitExceeded: cleanup_in_a_hurry() * 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. Error E-Mails ------------- * CELERY_SEND_TASK_ERROR_EMAILS If set to ``True``, errors in tasks will be sent to admins by e-mail. * ADMINS List of ``(name, email_address)`` tuples for the admins that should receive error e-mails. * SERVER_EMAIL The e-mail address this worker sends e-mails from. Default is ``"celery@localhost"``. * MAIL_HOST The mail server to use. Default is ``"localhost"``. * MAIL_HOST_USER Username (if required) to log on to the mail server with. * MAIL_HOST_PASSWORD Password (if required) to log on to the mail server with. * MAIL_PORT The port the mail server is listening on. Default is ``25``. Example E-Mail configuration ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This configuration enables the sending of error e-mails to ``george@vandelay.com`` and ``kramer@vandelay.com``: .. code-block:: python # Enables error e-mails. CELERY_SEND_TASK_ERROR_EMAILS = True # Name and e-mail addresses of recipients ADMINS = ( ("George Costanza", "george@vandelay.com"), ("Cosmo Kramer", "kosmo@vandelay.com"), ) # E-mail address used as sender (From field). SERVER_EMAIL = "no-reply@vandelay.com" # Mailserver configuration EMAIL_HOST = "mail.vandelay.com" EMAIL_PORT = 25 # EMAIL_HOST_USER = "servers" # EMAIL_HOST_PASSWORD = "s3cr3t" Events ------ * CELERY_SEND_EVENTS Send events so the worker can be monitored by tools like ``celerymon``. * CELERY_EVENT_EXCHANGE Name of the exchange to send event messages to. Default is ``"celeryevent"``. * CELERY_EVENT_EXCHANGE_TYPE The exchange type of the event exchange. Default is to use a ``direct`` exchange. * CELERY_EVENT_ROUTING_KEY Routing key used when sending event messages. Default is ``"celeryevent"``. * CELERY_EVENT_SERIALIZER Message serialization format used when sending event messages. Default is ``"json"``. Broadcast Commands ------------------ * CELERY_BROADCAST_QUEUE Name prefix for the queue used when listening for broadcast messages. The workers hostname will be appended to the prefix to create the final queue name. Default is ``"celeryctl"``. * CELERY_BROADCAST_EXCHANGE Name of the exchange used for broadcast messages. Default is ``"celeryctl"``. * CELERY_BROADCAST_EXCHANGE_TYPE Exchange type used for broadcast messages. Default is ``"fanout"``. 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. Default is ``[%(asctime)s: %(levelname)s/%(processName)s] %(message)s`` See the Python :mod:`logging` module for more information about log formats. * CELERYD_TASK_LOG_FORMAT The format to use for log messages logged in tasks. Can be overridden using the ``--loglevel`` option to ``celeryd``. Default is:: [%(asctime)s: %(levelname)s/%(processName)s] [%(task_name)s(%(task_id)s)] %(message)s See the Python :mod:`logging` module for more information about log formats. Custom Component Classes (advanced) ----------------------------------- * CELERYD_POOL Name of the task pool class used by the worker. Default is ``"celery.concurrency.processes.TaskPool"``. * CELERYD_LISTENER Name of the listener class used by the worker. Default is ``"celery.worker.listener.CarrotListener"``. * CELERYD_MEDIATOR Name of the mediator class used by the worker. Default is ``"celery.worker.controllers.Mediator"``. * CELERYD_ETA_SCHEDULER Name of the ETA scheduler class used by the worker. Default is ``"celery.worker.controllers.ScheduleController"``. 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.