Scaling GKE pods based on number of active connections per pod

Ok I managed to figure this out by looking up the schema for the HPA (https://docs.okd.io/latest/rest_api/apis-autoscaling/v2beta1.HorizontalPodAutoscaler.html).

In short, I was using the wrong metric type (as above you can see I am using "Pods", but I should be using "External").

The correct HPA specification is:

apiVersion: autoscaling/v2beta1kind: HorizontalPodAutoscalermetadata:  name: hpa-uat-active-connections  namespace: defaultspec:  minReplicas: 3  maxReplicas: 6  metrics:    - type: External      external:        metricName: custom.googleapis.com|nginx-ingress-controller|nginx_ingress_controller_nginx_process_connections        metricSelector:           matchLabels:            metric.labels.state: active            resource.labels.cluster_name: [redacted]        targetAverageValue: 5  scaleTargetRef:    apiVersion: apps/v1    kind: Deployment    name: [redacted]

As soon as I did this, things worked right away:

NAME                         REFERENCE                                 TARGETS        MINPODS   MAXPODS   REPLICAS   AGEhpa-uat-active-connections   Deployment/bustle-webapp-uat-deployment   334m/5 (avg)   3         6         3          30s