Running KEDA ScaledObject autoscaler on OpenShift

The VerticaAutoscaler custom resource (CR) supports two types of autoscaler, Horizontal Pod Autoscaler (HPA) and ScaledObject. In OpenShift, HPA has limited support for scaling based on Prometheus metrics as it relies on the Prometheus adapter, which is challenging to install. For OpenShift environments, ScaledObject is the recommended autoscaler.

To set up VerticaAutoscaler with ScaledObject in Openshift:

1. On OperatorHub Marketplace locate and install Custom Metrics Autoscaler. This installs all the required custom resources.

2. Navigate to Installed Operators, and select Custom Metrics Autoscaler. From the list of APIs, select KedaController and create an instance. You can keep the default values and ensure that watchNamespace is empty.

   Select YAML view to view the yaml file:

   kind: KedaController
   apiversion: keda.sh/v1alpha1
   metadata:
     name: keda
     namespace: opensfhits-keda
   spec:
     admissionWebhooks:
       logEncoder: console
       logLevel: info
     metricsServer:
       logLevel: '0'
     operator:
       logEncoder: console
       logLevel: info
    serviceAccount: null
    watchNamespace: ''
   

3. Next, deploy the VerticaAutoscaler CR with ScaledObject. For example:

   apiVersion: vertica.com/v1
   kind: VerticaAutoscaler
   metadata:
     name: v-scale
   spec:
     verticaDBName: v-test
     serviceName: primary1
     scalingGranularity: Pod
     customAutoscaler:
       type: ScaledObject
       scaledObject:
         minReplicas: 3
         maxReplicas: 12
         metrics:
         - name: vertica_sessions_running_total
           metricType: AverageValue
           prometheus:
             serverAddress: "http://prometheus-kube-prometheus-prometheus.prometheus.svc.cluster.local:9090"
             query: sum(vertica_sessions_running_counter{type="active", initiator="user", service="v-test-primary1"})
             threshold: 50