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Document updated on Jan 24, 2022

Gateway integration with RabbitMQ consumers

The AMQP component allows to send and receive messages to and from 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 namespaces backend/amqp/consumer or backend/amqp/producer.

To create Async agents that consume messages asynchronously and without requiring a user request, see Async Agents.

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.

Configuration

The consumer retrieves messages from the queue when a KrakenD endpoint plugs to its AMQP backend. The recommendation is to connect consumers to GET endpoints.

A single endpoint can consume messages from N queues, or can consume N messages from the same queue by adding N backends with the proper queue name.

See Async Agents to consume messages without an endpoint.

The needed configuration to run a consumer is:

{
    "backend": [{
        "host": ["amqp://guest:[email protected]:5672"],
        "disable_host_sanitize": true,
        "extra_config": {
            "backend/amqp/consumer": {
                "name": "queue-1",
                "exchange": "some-exchange",
                "durable": true,
                "delete": false,
                "no_wait": true,
                "no_local": false,
                "routing_key": ["#"],
                "prefetch_count": 10,
                "prefetch_size": 1024,
                "auto_ack": false
            }
        }
    }]
}
Fields of AMQP Consumer
* required fields

auto_ack boolean
When KrakenD retrieves the messages, regardless of the success or failure of the operation, it marks them as ACKnowledge.
Defaults to false
delete * boolean
Setting to false is recommended to avoid deletions when the consumer is disconnected.
Defaults to false
durable * boolean
Durable queues will survive server restarts and remain when there are no remaining consumers or bindings. true is recommended, but depends on the use case.
Defaults to false
exchange * string
The exchange name (must have a topic type if already exists).
Example: "some-exchange"
name * string
Queue name.
no_local boolean
The no_local flag is not supported by RabbitMQ.
no_wait * boolean
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 integer
The number of messages you want to prefetch prior to consume them.
Defaults to 10
prefetch_size integer
The number of bytes you want to use to prefetch messages.
Defaults to 1024
routing_key * array
The list of routing keys you will use to consume messages.
Example: "#"
Scarf

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