This document is for Kombu's development version, which can be significantly different from previous releases. Get the stable docs here: 5.3.

# Producers

## Basics

You can create a producer using a `Connection`:

    >>> producer = connection.Producer()

You can also instantiate `Producer` directly, it takes a channel or a connection as an argument:

    >>> with Connection('amqp://') as conn:
    ...     with conn.channel() as channel:
    ...          producer = Producer(channel)

Having a producer instance you can publish messages:

    >>> from kombu import Exchange

    >>> exchange = Exchange('name', type='direct')

    >>> producer.publish(
    ...      {'hello': 'world'},  # message to send
    ...      exchange=exchange,   # destination exchange
    ...      routing_key='rk',    # destination routing key,
    ...      declare=[exchange],  # make sure exchange is declared,
    ... )

Mostly you will be getting a connection from a connection pool, and this connection can be stale, or you could lose the connection in the middle of sending the message. Using retries is a good way to handle these intermittent failures:

    >>> producer.publish({'hello': 'world', ..., retry=True})

In addition a retry policy can be specified, which is a dictionary of parameters supported by the `retry_over_time()` function

    >>> producer.publish(
    ...     {'hello': 'world'}, ...,
    ...     retry=True,
    ...     retry_policy={
    ...         'interval_start': 0, # First retry immediately,
    ...         'interval_step': 2,  # then increase by 2s for every retry.
    ...         'interval_max': 30,  # but don't exceed 30s between retries.
    ...         'max_retries': 30,   # give up after 30 tries.
    ...     },
    ... )

The `declare` argument lets you pass a list of entities that must be declared before sending the message. This is especially important when using the `retry` flag, since the broker may actually restart during a retry in which case non-durable entities are removed.

Say you are writing a task queue, and the workers may have not started yet so the queues aren’t declared. In this case you need to define both the exchange, and the declare the queue so that the message is delivered to the queue while the workers are offline:

    >>> from kombu import Exchange, Queue
    >>> task_queue = Queue('tasks', Exchange('tasks'), routing_key='tasks')

    >>> producer.publish(
    ...     {'hello': 'world'}, ...,
    ...     retry=True,
    ...     exchange=task_queue.exchange,
    ...     routing_key=task_queue.routing_key,
    ...     declare=[task_queue],  # declares exchange, queue and binds.
    ... )

### Bypassing routing by using the anon-exchange

You may deliver to a queue directly, bypassing the brokers routing mechanisms, by using the “anon-exchange”: set the exchange parameter to the empty string, and set the routing key to be the name of the queue:

    >>> producer.publish(
    ...     {'hello': 'world'},
    ...     exchange='',
    ...     routing_key=task_queue.name,
    ... )

## Serialization

Json is the default serializer when a non-string object is passed to publish, but you can also specify a different serializer:

    >>> producer.publish({'hello': 'world'}, serializer='pickle')

See Serialization for more information.

## Reference

class kombu.Producer(channel, exchange=None, routing_key=None, serializer=None, auto_declare=None, compression=None, on_return=None)

  Message Producer.

  ### Arguments:

  > channel (kombu.Connection, ChannelT): Connection or channel. exchange (kombu.entity.Exchange, str): Optional default exchange. routing_key (str): Optional default routing key. serializer (str): Default serializer. Default is “json”. compression (str): Default compression method.

  > > Default is no compression.

  > auto_declare (bool): Automatically declare the default exchange

  >   at instantiation. Default is `True`.

  > on_return (Callable): Callback to call for undeliverable messages,

  >   when the mandatory or immediate arguments to `publish()` is used. This callback needs the following signature: (exception, exchange, routing_key, message). Note that the producer needs to drain events to use this feature.

  auto_declare = True

    By default, if a default exchange is set, that exchange will be declare when publishing a message.

  compression = None

    Default compression method. Disabled by default.

  declare()

    Declare the exchange.

    #### Note:

    > This happens automatically at instantiation when the `auto_declare` flag is enabled.

  exchange = None

    Default exchange

  maybe_declare(entity, retry=False, **retry_policy)

    Declare exchange if not already declared during this session.

  on_return = None

    Basic return callback.

  publish(body, routing_key=None, delivery_mode=None, mandatory=False, immediate=False, priority=0, content_type=None, content_encoding=None, serializer=None, headers=None, compression=None, exchange=None, retry=False, retry_policy=None, declare=None, expiration=None, timeout=None, confirm_timeout=None, **properties)

    Publish message to the specified exchange.

    #### Arguments:

    > body (Any): Message body. routing_key (str): Message routing key. delivery_mode (enum): See `delivery_mode`. mandatory (bool): Currently not supported. immediate (bool): Currently not supported. priority (int): Message priority. A number between 0 and 9. content_type (str): Content type. Default is auto-detect. content_encoding (str): Content encoding. Default is auto-detect. serializer (str): Serializer to use. Default is auto-detect. compression (str): Compression method to use. Default is none. headers (Dict): Mapping of arbitrary headers to pass along

    > > with the message body.

    > exchange (kombu.entity.Exchange, str): Override the exchange.

    >   Note that this exchange must have been declared.

    > declare (Sequence[EntityT]): Optional list of required entities

    >   that must have been declared before publishing the message. The entities will be declared using `maybe_declare()`.

    > retry (bool): Retry publishing, or declaring entities if the

    >   connection is lost.

    > retry_policy (Dict): Retry configuration, this is the keywords

    >   supported by `ensure()`.

    > expiration (float): A TTL in seconds can be specified per message.

    >   Default is no expiration.

    > timeout (float): Set timeout to wait maximum timeout second

    >   for message to publish.

    > confirm_timeout (float): Set confirm timeout to wait maximum timeout second

    >   for message to confirm publishing if the channel is set to confirm publish mode.

    > **properties (Any): Additional message properties, see AMQP spec.

  revive(channel)

    Revive the producer after connection loss.

  routing_key = ''

    Default routing key.

  serializer = None

    Default serializer to use. Default is JSON.