This document describes the configuration options available.
If you're using the default loader, you must create the :file:`celeryconfig.py` module and make sure it is available on the Python path.
- Example configuration file
- Configuration Directives
- Concurrency settings
- Task result backend settings
- Database backend settings
- AMQP backend settings
- Cache backend settings
- Tokyo Tyrant backend settings
- Redis backend settings
- MongoDB backend settings
- Message Routing
- Broker Settings
- Task execution settings
- Worker: celeryd
- Error E-Mails
- Events
- Broadcast Commands
- Logging
- Custom Component Classes (advanced)
- Periodic Task Server: celerybeat
- Monitor Server: celerymon
This is an example configuration file to get you started. It should contain all you need to run a basic Celery set-up.
# 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".. setting:: CELERYD_CONCURRENCY
The number of concurrent worker processes/threads/green threads, executing tasks.
Defaults to the number of available CPUs.
.. setting:: 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 is usually a good choice, 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 distributed to the workers.
.. setting:: 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. See :ref:`conf-database-result-backend`.
- cache
- Use memcached to store the results. See :ref:`conf-cache-result-backend`.
- mongodb
- Use MongoDB to store the results. See :ref:`conf-mongodb-result-backend`.
- redis
- Use Redis to store the results. See :ref:`conf-redis-result-backend`.
- tyrant
- Use Tokyo Tyrant to store the results. See :ref:`conf-tyrant-result-backend`.
- amqp
- Send results back as AMQP messages See :ref:`conf-amqp-result-backend`.
.. setting:: CELERY_RESULT_DBURI
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:
# 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:[email protected]:1521/sidname"See Connection String for more information about connection strings.
.. setting:: CELERY_RESULT_ENGINE_OPTIONS
To specify additional SQLAlchemy database engine options you can use the :setting:`CELERY_RESULT_ENGINE_OPTIONS` setting:
# echo enables verbose logging from SQLAlchemy.
CELERY_RESULT_ENGINE_OPTIONS = {"echo": True}
CELERY_RESULT_BACKEND = "database"
CELERY_RESULT_DBURI = "mysql://user:password@host/dbname".. setting:: CELERY_AMQP_TASK_RESULT_EXPIRES
The time in seconds of which the task result queues should expire.
Note
AMQP result expiration requires RabbitMQ versions 2.1.0 and higher.
.. setting:: CELERY_AMQP_TASK_RESULT_CONNECTION_MAX
Maximum number of connections used by the AMQP result backend simultaneously.
Default is 1 (a single connection per process).
.. setting:: CELERY_RESULT_EXCHANGE
Name of the exchange to publish results in. Default is "celeryresults".
.. setting:: CELERY_RESULT_EXCHANGE_TYPE
The exchange type of the result exchange. Default is to use a direct exchange.
.. setting:: CELERY_RESULT_SERIALIZER
Result message serialization format. Default is "pickle". See :ref:`executing-serializers`.
.. setting:: CELERY_RESULT_PERSISTENT
If set to :const:`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.
CELERY_RESULT_BACKEND = "amqp"
CELERY_AMQP_TASK_RESULT_EXPIRES = 18000 # 5 hours.Note
The cache backend supports the pylibmc and python-memcached libraries. The latter is used only if pylibmc is not installed.
.. setting:: CELERY_CACHE_BACKEND
Using a single memcached server:
CELERY_CACHE_BACKEND = 'memcached://127.0.0.1:11211/'Using multiple memcached servers:
CELERY_RESULT_BACKEND = "cache"
CELERY_CACHE_BACKEND = 'memcached://172.19.26.240:11211;172.19.26.242:11211/'.. setting:: CELERY_CACHE_BACKEND_OPTIONS
The "dummy" backend stores the cache in memory only:
CELERY_CACHE_BACKEND = "dummy"
You can set pylibmc options using the :setting:`CELERY_CACHE_BACKEND_OPTIONS` setting:
CELERY_CACHE_BACKEND_OPTIONS = {"binary": True,
"behaviors": {"tcp_nodelay": True}}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:
.. setting:: TT_HOST
Host name of the Tokyo Tyrant server.
.. setting:: TT_PORT
The port the Tokyo Tyrant server is listening to.
CELERY_RESULT_BACKEND = "tyrant"
TT_HOST = "localhost"
TT_PORT = 1978Note
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.
.. setting:: REDIS_HOST
Host name of the Redis database server. e.g. "localhost".
.. setting:: REDIS_PORT
Port to the Redis database server. e.g. 6379.
.. setting:: REDIS_DB
Database number to use. Default is 0
.. setting:: REDIS_PASSWORD
Password used to connect to the database.
CELERY_RESULT_BACKEND = "redis"
REDIS_HOST = "localhost"
REDIS_PORT = 6379
REDIS_DB = 0
REDIS_CONNECT_RETRY = TrueNote
The MongoDB backend requires the :mod:`pymongo` library: http://github.com/mongodb/mongo-python-driver/tree/master
.. setting:: CELERY_MONGODB_BACKEND_SETTINGS
This is a dict supporting the following keys:
- host
- Host name 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".
CELERY_RESULT_BACKEND = "mongodb"
CELERY_MONGODB_BACKEND_SETTINGS = {
"host": "192.168.1.100",
"port": 30000,
"database": "mydb",
"taskmeta_collection": "my_taskmeta_collection",
}.. setting:: CELERY_QUEUES
The mapping of queues the worker consumes from. This is a dictionary of queue name/options. See :ref:`guide-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.
.. setting:: CELERY_ROUTES
A list of routers, or a single router used to route tasks to queues. When deciding the final destination of a task the routers are consulted in order. See :ref:`routers` for more information.
.. setting:: CELERY_CREATE_MISSING_QUEUES
If enabled (default), any queues specified that is not defined in :setting:`CELERY_QUEUES` will be automatically created. See :ref:`routing-automatic`.
.. setting:: CELERY_DEFAULT_QUEUE
The queue used by default, if no custom queue is specified. This queue must be listed in :setting:`CELERY_QUEUES`. The default is: celery.
.. seealso::
:ref:`routing-changing-default-queue`
.. setting:: CELERY_DEFAULT_EXCHANGE
Name of the default exchange to use when no custom exchange is specified. The default is: celery.
.. setting:: CELERY_DEFAULT_EXCHANGE_TYPE
Default exchange type used when no custom exchange is specified. The default is: direct.
.. setting:: CELERY_DEFAULT_ROUTING_KEY
The default routing key used when sending tasks. The default is: celery.
.. setting:: CELERY_DEFAULT_DELIVERY_MODE
Can be transient or persistent. The default is to send persistent messages.
.. setting:: BROKER_BACKEND
The Kombu transport to use. Default is amqplib.
You can use a custom transport class name, or select one of the
built-in transports: amqplib, pika, redis, beanstalk,
sqlalchemy, django, mongodb, couchdb.
.. setting:: BROKER_HOST
Hostname of the broker.
.. setting:: BROKER_PORT
Custom port of the broker. Default is to use the default port for the selected backend.
.. setting:: BROKER_USER
Username to connect as.
.. setting:: BROKER_PASSWORD
Password to connect with.
.. setting:: BROKER_VHOST
Virtual host. Default is "/".
.. setting:: BROKER_USE_SSL
Use SSL to connect to the broker. Off by default. This may not be supported by all transports.
.. setting:: BROKER_CONNECTION_TIMEOUT
The default timeout in seconds before we give up establishing a connection to the AMQP server. Default is 4 seconds.
.. setting:: CELERY_BROKER_CONNECTION_RETRY
Automatically try to re-establish the connection to the AMQP broker if lost.
The time between retries is increased for each retry, and is not exhausted before :setting:`CELERY_BROKER_CONNECTION_MAX_RETRIES` is exceeded.
This behavior is on by default.
.. setting:: 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 :const:`0` or :const:`None`, we will retry forever.
Default is 100 retries.
.. setting:: CELERY_ALWAYS_EAGER
If this is :const:`True`, all tasks will be executed locally by blocking until
the task returns. apply_async() and Task.delay() will return
an :class:`~celery.result.EagerResult` instance, which emulates the API
and behavior of :class:`~celery.result.AsyncResult`, except the result
is already evaluated.
That is, tasks will be executed locally instead of being sent to the queue.
.. setting:: CELERY_EAGER_PROPAGATES_EXCEPTIONS
If this is :const:`True`, eagerly executed tasks (applied by task.apply(), or when the :setting:`CELERY_ALWAYS_EAGER` setting is enabled), will propagate exceptions.
It's the same as always running apply() with throw=True.
.. setting:: 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 :setting:`CELERY_STORE_ERRORS_EVEN_IF_IGNORED`.
.. setting:: CELERY_MESSAGE_COMPRESSION
Default compression used for task messages.
Can be "gzip", "bzip2" (if available), or any custom
compression schemes registered in the Kombu compression registry.
The default is to send uncompressed messages.
.. setting:: 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.backend_cleanup`).
Note
For the moment this only works with the database, cache, redis and MongoDB backends. For the AMQP backend see :setting:`CELERY_AMQP_TASK_RESULT_EXPIRES`.
When using the database or MongoDB backends, celerybeat must be running for the results to be expired.
.. setting:: CELERY_MAX_CACHED_RESULTS
Result backends caches ready results used by the client.
This is the total number of results to cache before older results are evicted. The default is 5000.
.. setting:: CELERY_TRACK_STARTED
If :const:`True` the task will report its status as "started" when the task is executed by a worker. The default value is :const:`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" state can be useful for when there are long running tasks and there is a need to report which task is currently running.
.. setting:: CELERY_TASK_SERIALIZER
A string identifying the default serialization method to use. Can be pickle (default), json, yaml, msgpack or any custom serialization methods that have been registered with :mod:`kombu.serialization.registry`.
.. seealso::
:ref:`executing-serializers`.
.. setting:: CELERY_TASK_PUBLISH_RETRY
Decides if publishing task messages will be retried in the case of connection loss or other connection errors. See also :setting:`CELERY_TASK_PUBLISH_RETRY_POLICY`.
Disabled by default.
.. setting:: CELERY_TASK_PUBLISH_RETRY_POLICY
Defines the default policy when retrying publishing a task message in the case of connection loss or other connection errors.
This is a mapping that must contain the following keys:
max_retries
Maximum number of retries before giving up, in this case the exception that caused the retry to fail will be raised.
A value of 0 or :const:`None` means it will retry forever.
The default is to retry 3 times.
interval_start
Defines the number of seconds (float or integer) to wait between retries. Default is 0, which means the first retry will be instantaneous.
interval_step
On each consecutive retry this number will be added to the retry delay (float or integer). Default is 0.2.
interval_max
Maximum number of seconds (float or integer) to wait between retries. Default is 0.2.
With the default policy of:
{"max_retries": 3,
"interval_start": 0,
"interval_step": 0.2,
"interval_max": 0.2}
the maximum time spent retrying will be 0.4 seconds. It is set relatively short by default because a connection failure could lead to a retry pile effect if the broker connection is down: e.g. many web server processes waiting to retry blocking other incoming requests.
.. setting:: 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.
.. setting:: CELERY_DISABLE_RATE_LIMITS
Disable all rate limits, even if tasks has explicit rate limits set.
.. setting:: 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.
.. seealso::
FAQ: :ref:`faq-acks_late-vs-retry`.
.. setting:: 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.
.. setting:: 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.
.. setting:: 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.
.. setting:: CELERYD_TASK_SOFT_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.
Example:
from celery.task import task
from celery.exceptions import SoftTimeLimitExceeded
@task()
def mytask():
try:
return do_work()
except SoftTimeLimitExceeded:
cleanup_in_a_hurry().. setting:: CELERY_STORE_ERRORS_EVEN_IF_IGNORED
If set, the worker stores all task errors in the result store even if :attr:`Task.ignore_result <celery.task.base.Task.ignore_result>` is on.
.. setting:: CELERYD_STATE_DB
Name of the file used to stores persistent worker state (like revoked tasks). Can be a relative or absolute path, but be aware that the suffix .db may be appended to the file name (depending on Python version).
Can also be set via the :option:`--statedb` argument to :mod:`~celery.bin.celeryd`.
Not enabled by default.
.. setting:: CELERYD_ETA_SCHEDULER_PRECISION
Set the maximum time in seconds that the ETA scheduler can sleep between rechecking the schedule. Default is 1 second.
Setting this value to 1 second means the schedulers precision will be 1 second. If you need near millisecond precision you can set this to 0.1.
.. setting:: CELERYD_SEND_TASK_ERROR_EMAILS
The default value for the Task.send_error_emails attribute, which if set to :const:`True` means errors occurring during task execution will be sent to :setting:`ADMINS` by e-mail.
.. setting:: CELERY_TASK_ERROR_WHITELIST
A white list of exceptions to send error e-mails for.
.. setting:: ADMINS
List of (name, email_address) tuples for the administrators that should receive error e-mails.
.. setting:: SERVER_EMAIL
The e-mail address this worker sends e-mails from. Default is celery@localhost.
.. setting:: MAIL_HOST
The mail server to use. Default is "localhost".
.. setting:: MAIL_HOST_USER
User name (if required) to log on to the mail server with.
.. setting:: MAIL_HOST_PASSWORD
Password (if required) to log on to the mail server with.
.. setting:: MAIL_PORT
The port the mail server is listening on. Default is 25.
This configuration enables the sending of error e-mails to [email protected] and [email protected]:
# Enables error e-mails.
CELERY_SEND_TASK_ERROR_EMAILS = True
# Name and e-mail addresses of recipients
ADMINS = (
("George Costanza", "[email protected]"),
("Cosmo Kramer", "[email protected]"),
)
# E-mail address used as sender (From field).
SERVER_EMAIL = "[email protected]"
# Mailserver configuration
EMAIL_HOST = "mail.vandelay.com"
EMAIL_PORT = 25
# EMAIL_HOST_USER = "servers"
# EMAIL_HOST_PASSWORD = "s3cr3t".. setting:: CELERY_SEND_EVENTS
Send events so the worker can be monitored by tools like celerymon.
.. setting:: CELERY_SEND_TASK_SENT_EVENT
If enabled, a task-sent event will be sent for every task so tasks can be tracked before they are consumed by a worker.
Disabled by default.
.. setting:: CELERY_EVENT_QUEUE
Name of the queue to consume event messages from. Default is "celeryevent".
.. setting:: CELERY_EVENT_EXCHANGE
Name of the exchange to send event messages to. Default is "celeryevent".
.. setting:: CELERY_EVENT_EXCHANGE_TYPE
The exchange type of the event exchange. Default is to use a "direct" exchange.
.. setting:: CELERY_EVENT_ROUTING_KEY
Routing key used when sending event messages. Default is "celeryevent".
.. setting:: CELERY_EVENT_SERIALIZER
Message serialization format used when sending event messages. Default is "json". See :ref:`executing-serializers`.
.. setting:: CELERY_BROADCAST_QUEUE
Name prefix for the queue used when listening for broadcast messages. The workers host name will be appended to the prefix to create the final queue name.
Default is "celeryctl".
.. setting:: CELERY_BROADCASTS_EXCHANGE
Name of the exchange used for broadcast messages.
Default is "celeryctl".
.. setting:: CELERY_BROADCAST_EXCHANGE_TYPE
Exchange type used for broadcast messages. Default is "fanout".
.. setting:: CELERYD_HIJACK_ROOT_LOGGER
By default any previously configured logging options will be reset, because the Celery apps "hijacks" the root logger.
If you want to customize your own logging then you can disable this behavior.
Note
Logging can also be customized by connecting to the :signal:`celery.signals.setup_logging` signal.
.. setting:: CELERYD_LOG_FILE
The default file name the worker daemon logs messages to. Can be overridden using the :option:`--logfile` option to :mod:`~celery.bin.celeryd`.
The default is :const:`None` (stderr)
.. setting:: CELERYD_LOG_LEVEL
Worker log level, can be one of :const:`DEBUG`, :const:`INFO`, :const:`WARNING`, :const:`ERROR` or :const:`CRITICAL`.
Can also be set via the :option:`--loglevel` argument to :mod:`~celery.bin.celeryd`.
See the :mod:`logging` module for more information.
.. setting:: CELERYD_LOG_COLOR
Enables/disables colors in logging output by the Celery apps.
By default colors are enabled if
- the app is logging to a real terminal, and not a file.
- the app is not running on Windows.
.. setting:: 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.
.. setting:: CELERYD_TASK_LOG_FORMAT
The format to use for log messages logged in tasks. Can be overridden using the :option:`--loglevel` option to :mod:`~celery.bin.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.
.. setting:: CELERY_REDIRECT_STDOUTS
If enabled stdout and stderr will be redirected to the current logger.
Enabled by default. Used by :program:`celeryd` and :program:`celerybeat`.
.. setting:: CELERY_REDIRECT_STDOUTS_LEVEL
The log level output to stdout and stderr is logged as. Can be one of :const:`DEBUG`, :const:`INFO`, :const:`WARNING`, :const:`ERROR` or :const:`CRITICAL`.
Default is :const:`WARNING`.
.. setting:: CELERYD_POOL
Name of the pool class used by the worker.
You can use a custom pool class name, or select one of
the built-in aliases: processes, eventlet, gevent.
Default is processes.
.. setting:: CELERYD_AUTOSCALER
Name of the autoscaler class to use.
Default is "celery.worker.autoscale.Autoscaler".
.. setting:: CELERYD_CONSUMER
Name of the consumer class used by the worker. Default is :class:`celery.worker.consumer.Consumer`
.. setting:: CELERYD_MEDIATOR
Name of the mediator class used by the worker. Default is :class:`celery.worker.controllers.Mediator`.
.. setting:: CELERYD_ETA_SCHEDULER
Name of the ETA scheduler class used by the worker. Default is :class:`celery.utils.timer2.Timer`, or one overrided by the pool implementation.
.. setting:: CELERYBEAT_SCHEDULE
The periodic task schedule used by :mod:`~celery.bin.celerybeat`. See :ref:`beat-entries`.
.. setting:: CELERYBEAT_SCHEDULER
The default scheduler class. Default is "celery.beat.PersistentScheduler".
Can also be set via the :option:`-S` argument to :mod:`~celery.bin.celerybeat`.
.. setting:: CELERYBEAT_SCHEDULE_FILENAME
Name of the file used by PersistentScheduler to store the last run times of periodic tasks. Can be a relative or absolute path, but be aware that the suffix .db may be appended to the file name (depending on Python version).
Can also be set via the :option:`--schedule` argument to :mod:`~celery.bin.celerybeat`.
.. setting:: CELERYBEAT_MAX_LOOP_INTERVAL
The maximum number of seconds :mod:`~celery.bin.celerybeat` can sleep between checking the schedule. Default is 300 seconds (5 minutes).
.. setting:: CELERYBEAT_LOG_FILE
The default file name to log messages to. Can be overridden using the --logfile option to :mod:`~celery.bin.celerybeat`.
The default is :const:`None` (stderr).
.. setting:: CELERYBEAT_LOG_LEVEL
Logging level. Can be any of :const:`DEBUG`, :const:`INFO`, :const:`WARNING`, :const:`ERROR`, or :const:`CRITICAL`.
Can also be set via the :option:`--loglevel` argument to :mod:`~celery.bin.celerybeat`.
See the :mod:`logging` module for more information.
.. setting:: CELERYMON_LOG_FILE
The default file name to log messages to. Can be overridden using the :option:`--logfile` argument to celerymon.
The default is :const:`None` (stderr)
.. setting:: CELERYMON_LOG_LEVEL
Logging level. Can be any of :const:`DEBUG`, :const:`INFO`, :const:`WARNING`, :const:`ERROR`, or :const:`CRITICAL`.
See the :mod:`logging` module for more information.