Trigger functions from RabbitMQ¶

Trigger OpenFaaS functions from RabbitMQ messages.

Note: This feature is included for OpenFaaS Standard & For Enterprises customers.

Installation¶

Setup the connector

You can install the RabbitMQ connector using its helm chart.

The values.yaml file can be customised to suit your needs.

Configure the connector for you needs by defining a values.yaml file


rabbitmqURL: "amqp://rabbitmq.rabbitmq.svc.cluster.local:5672"

queues:
  - name: queue1
    durable: true

Use the queues parameter to configure a list of queues to which the connector should subscribe. When a message is received on a queue, the connector will invoke any function that has the queue name listed in its topic annotation.

Queue configuration:

name - The name of the queue. (Required)
durable - Specifies whether the queue should survive broker restarts.
nowait - Whether to wait for confirmation from the server when declaring the queue.
autodelete - Whether the queue should be deleted automatically when no consumers are connected.
exclusive - Specifies whether the queue should be exclusive to the connection that created it.

If your RabbitMQ requires a TLS connection make sure to use amqps:// as the scheme in the url.

Usage¶

To test the connector, you can deploy the printer function. It prints out the HTTP headers and body of any invocation.

Add an annotation topic=queue1 so that the function is invoked for any message published to the queue with name queue1. Each time a function is invoked by the connector it will receive the message from the queue as the HTTP body.


faas-cli store deploy printer \
  --annotation topic=queue1

Publish a message on the queue for testing. We will be using the RabbitMQ management CLI for this.


./rabbitmqadmin publish \
  routing_key="queue1" payload='Hello, Task Queue!' properties='{"message_id":"1"}'

Take a look at the logs of the printer function to inspect the invocations made by the connector. You should see the following output:


faas-cli logs printer

2024-12-03T14:36:03Z X-Connector=[connector-sdk openfaasltd/rabbitmq-connector]
2024-12-03T14:36:03Z X-Topic=[queue1]
2024-12-03T14:36:03Z Accept-Encoding=[gzip]
2024-12-03T14:36:03Z Content-Type=[text/plain]
2024-12-03T14:36:03Z X-Call-Id=[d0ab9f9e-0c93-46b1-a4dd-695a037acb38]
2024-12-03T14:36:03Z 2024/12/03 14:36:03 POST / - 202 Accepted - ContentLength: 0B (0.0003s)
2024-12-03T14:36:03Z X-Forwarded-Host=[gateway.openfaas:8080]
2024-12-03T14:36:03Z X-Rabbitmq-Msg-Id=[1]
2024-12-03T14:36:03Z X-Start-Time=[1733236563468386644]
2024-12-03T14:36:03Z X-Forwarded-For=[10.42.0.13:55796]
2024-12-03T14:36:03Z X-Rabbitmq-Routing-Key=[queue1]
2024-12-03T14:36:03Z User-Agent=[openfaas-gateway/0.4.34]
2024-12-03T14:36:03Z 
2024-12-03T14:36:03Z Hello, Task Queue!
2024-12-03T14:36:03Z

Additional headers are made available to the request. These headers contain RabbitMQ message metadata.

X-Topic - topic that triggered the function.
X-Rabbitmq-Msg-Id - the message identifier.
X-Rabbitmq-Routing-Key - the routing key of the message.

The default content-type is configured as text/plain, but can be changed to another content-type such as application/json or application/octet-stream by the values.yaml file for the connector.

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