RabbitMQ - Unacked Messages not considering for scaling the pods

[Sathya-omnius]

HI Team,

we are facing an issue that Keda is not scaling when we have unacked messages in the queue , currently we are using cloudampq which does not support any unencrypted connections i.e http so as per the Keda official documentation it is mentioned that we need to use http in order to include unacked messages as part of scaling.

could some one provide alternate solution what would be work around in order to scale the pods considering unacked messages .

error which we are getting with http:
2025-01-14T11:31:32Z ERROR scale_handler error getting scale decision {"scaledObject.Namespace": "trainer", "scaledObject.Name": "predictions-0a8f3576-1-scaledobject", "scaler": "rabbitMQScaler", "error": "error inspecting rabbitMQ: Get "[http://user:[email protected]:5671/api/queues/%2F/q-prediction.0a8f3576-d177-4ea7-887e-35bed1115756.document-classification](http://user:[email protected]:5671/api/queues/%2F/q-prediction.0a8f3576-d177-4ea7-887e-35bed1115756.document-classification%5C)": net/http: HTTP/1.x transport connection broken: malformed HTTP response "AMQP\x00\x00\t\x01""}

[mauvilsa]

As written in the docs, "if you have unacknowledged messages and want to have these counted for the scaling to happen, make sure to utilize the http". So using http is the solution. Though, the docs could explain better. Why does it have to be http? Is it that it is impossible to support this with amqp, or is it a pending improvement?

Also, since there is no explanation, then for someone using amqps (because they need secure connections), then a switch to http looks like a no go because it would be insecure. Later in the docs there is the "lts" parameter, but this is confusing. Why not call this https? From my understanding http+tls is the same as http. If there is no difference, then using https makes things less confusing.

[zroubalik]

If I recall correctly the amqp protocol doesn't support this, so that's why http one needs to be used. CC @JorTurFer

[mauvilsa]

We also had more confusing behaviors. We added protocol http and tls enable. But then set the host to be port 15672 that doesn't support tls. But keda still worked. Furthermore, in one test we changed tls to "invalid" value, and in a different test we added an unexpected key, and again in both tests keda still worked. So it seems the validation is not strict, which makes it hard to know whether things are configured correctly.

[zroubalik]

Yeah, this particular scaler was updated over the years to support mutliple different features, so there might be some edge cases.
There are plans to refactor this one eventually: #6352

[JorTurFer]

AMQP doesn't support unacked messages, the only option is using HTTP or Prometheus. Said this, RabbitMQ team has deprecated the HTTP metrics in favor of scrapping them via Prometheus, so I'd suggest to change to Prometheus rather than to HTTP, RabbitMQ 4 has the HTTP metrics disabled as default