How to prevent scale to 0 during RollingUpdates

[jamesoneill997]

Relatively inxperienced with Keda, so my apologies if this is a bit of a noob question.

We use keda for scaling within pipelines and one thing that I'm a bit puzzled on is how to handle scaling during rollingUpdates. I wish to allow replicas to scale to 0 if there is no volume, however, I believe that setting minReplicas: 0 will also mean that during a rollingUpdate of pods within the pipeline, replicas will be allowed to scale to 0, which is not something that I want.

For pods within the pipeline, we are using an updateStrategy like so:

  updateStrategy:
    rollingUpdate:
      maxUnavailable: 25%

However, I'm not sure whether this is relevant when scaling via Keda, as it seems like the Keda scaler config below would take precedence:

spec:
  minReplicaCount: {{ $values.minReplicaCount }}
  maxReplicaCount: 2

If minReplicaCount is >=1, then this is fine. But in some cases, I will want to allow an environment to scale down to 0, and the behaviour that I have noticed is that in environments where we allow scale to 0, they seem to break if a configuration change is applied while traffic is being processed.

So, is it possible to allow scale to 0 but also change the behaviour on rollingUpdate? From a look through the docs, I don't think that it is.

Apologies again if I've missed something here. Thanks in advance.