Document updated on Jan 24, 2022

Gateway integration with RabbitMQ producers

The AMQP producer component allows to send messages to a queue through the API Gateway.

The configuration of the queue is a straightforward process. To connect the endpoints to the messaging system you only need to include the extra_config key with the namespace backend/amqp/producer.

The parameters of this integration follow the AMQP specification. To understand what are the implications of a certain parameter, see the AMQP Complete Reference Guide.

KrakenD creates both the exchange and the queue for you.

Producer Configuration

{
    "backend": [{
        "host": ["amqp://guest:[email protected]:5672"],
        "disable_host_sanitize": true,
        "extra_config": {
            "backend/amqp/producer": {
                "name": "queue-1",
                "exchange": "some-exchange",
                "durable": true,
                "delete": false,
                "no_wait": true,
                "no_local": false,
                "routing_key": "#",
                "prefetch_count": 10,
                "prefetch_size": 1024,
                "mandatory": false,
                "immediate": false
            }
        }
    }]
}

• name - string as the queue name
• exchange - string the exchange name (must have a topic type if already exists).
• routing_key - string: The routing keys you will use to send messages.
• durable - bool true is recommended, but depends on the use case. Durable queues will survive server restarts and remain when there are no remaining consumers or bindings.
• delete - bool false is recommended to avoid deletions when the producer is disconnected
• no_wait - bool: When true, do not wait for the server to confirm the request and immediately begin deliveries. If it is not possible to consume, a channel exception will be raised and the channel will be closed.
• prefetch_count - int (optional): Is the number of messages you want to prefetch prior to consume them.
• prefetch_size - int (optional): Is the number of bytes you want to use to prefetch messages.
• mandatory - bool (optional): The exchange must have at least one queue bound when true. Defaults to false.
• immediate - bool (optional): A consumer must be connected to the queue when true. Defaults to false.

Additionally, the items below are parameter keys that can be present in the endpoint URL and are passed to the producer. Parameters need capitalization on the first letter.

• exp_key - string
• reply_to_key - string
• msg_id_key - string
• priority_key - string - Key of the request parameters that is used as the priority value for the produced message.
• routing_key - string - Key of the request parameters that is used as the routing value for the produced message.

For instance, an endpoint URL could be declared as /produce/{a}/{b}/{id}/{prio}/{route} and the producer knows how to map them with a configuration like this:

{
    ...
    "exp_key":"A",
    "reply_to_key":"B",
    "msg_id_key":"Id",
    "priority_key":"Prio",
    "routing_key":"Route"
}