Fixed KubeDownscaler Ignoring Keda ScaledObjects if the "paused-replicas" annotation is already present

[samuel-esp]

WIth this PR I fixed a bug that prevented ScaledObjects from being paused if the "paused-replicas" annotation was already present inside the object

Motivation

If, for some reason, the annotation autoscaling.keda.sh/paused-replicas is already present in the ScaledObject, the KubeDownscaler won't process the resource

This bug can happen if the developers incorrectly put this annotation at object creation.

For example this object:

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: cron-scaledobject-2
  annotations:
    autoscaling.keda.sh/paused-replicas: "2"
spec:
  scaleTargetRef:
    name: hamster
  minReplicaCount: 2
  maxReplicaCount: 10
  triggers:
  - type: cron
    metadata:
      start: 0 0 * * *
      end: 0 6 * * *
      desiredReplicaCount: '10'

will be logged in this way inside the Kube-Downscaler

2024-01-31 13:21:44,135 DEBUG: ScaledObject default/cron-scaledobject-2 has 0 replicas (original: None, uptime: Mon-Sun 07:30-10:45 CET)

This is because the keda.py was defined as such

class ScaledObject(NamespacedAPIObject):

    """Support the ScaledObject resource (https://keda.sh/docs/2.7/concepts/scaling-deployments/#scaledobject-spec)."""

    version = "keda.sh/v1alpha1"
    endpoint = "scaledobjects"
    kind = "ScaledObject"

    keda_pause_annotation = "autoscaling.keda.sh/paused-replicas"

    @property
    def replicas(self):
        replicas = 0 if ScaledObject.keda_pause_annotation in self.annotations else 1
        return replicas

the method "replicas" is called inside the "get_replicas" function of the scaler.py class and it always returns 0 with a ScaledObjects defined as the one above

Changes

How the fix works: Each ScaledObjects will be scaled to 0 regardless of them having the annotation or not. However if the annotation autoscaling.keda.sh/paused-replicas was already present and with a value (like 2 or 3), during the next Cluster Uptime the ScaledObject will be restored at that configuration. The previous configuration "paused configuration" is saved inside a new annotation called downscaler/original-pause-replicas

Tests done

Built the image and followed the workflow described above

TODO

• I've assigned myself to this PR