Balancerd Size Recommendations and Horizontal Pod Autoscaling

[jubrad]

Problem

Balancerd defaults are undersized for production workloads and cannot scale to handle traffic spikes.

Solution

1. Provide recommendation in sample config to set balancerd to 2 cores of CPU and 2Gi memory for production workloads.
2. Provide ability for balancerd to scale automatically using horizontal pod autoscaler.

# Example Balancerd HPA config
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: balancer
  namespace: mz-balancer
spec:
  behavior:
    scaleDown:
      policies:
      - periodSeconds: 15
        type: Percent
        value: 100
      selectPolicy: Max
      stabilizationWindowSeconds: 1800
    scaleUp:
      policies:
      - periodSeconds: 15
        type: Pods
        value: 4
      - periodSeconds: 15
        type: Percent
        value: 100
      selectPolicy: Max
      stabilizationWindowSeconds: 180
  maxReplicas: 10
  metrics:
  - resource:
      name: memory
      target:
        averageUtilization: 50
        type: Utilization
    type: Resource
  - resource:
      name: cpu
      target:
        averageUtilization: 50
        type: Utilization
    type: Resource
  minReplicas: 1
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: balancer