# HorizontalPodAutoscaler for rdev-worker based on queue depth.
# Scales workers up when pending tasks accumulate, scales down when queue drains.
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: rdev-worker
  namespace: rdev
  labels:
    app.kubernetes.io/name: rdev-worker
    app.kubernetes.io/part-of: rdev
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: rdev-worker
  minReplicas: 1
  maxReplicas: 10

  metrics:
    # Scale based on pending tasks in the work queue
    - type: External
      external:
        metric:
          name: rdev_pending_tasks
        target:
          type: AverageValue
          # Target 2 pending tasks per worker
          # With 2 workers and 4 pending, we'd scale up
          averageValue: "2"

  behavior:
    # Scale up quickly when work accumulates
    scaleUp:
      stabilizationWindowSeconds: 60  # Wait 1 minute before scaling up again
      policies:
        - type: Pods
          value: 2  # Add up to 2 pods at a time
          periodSeconds: 60
        - type: Percent
          value: 100  # Or double the current count
          periodSeconds: 60
      selectPolicy: Max

    # Scale down slowly to avoid thrashing
    scaleDown:
      stabilizationWindowSeconds: 300  # Wait 5 minutes before scaling down
      policies:
        - type: Pods
          value: 1  # Remove 1 pod at a time
          periodSeconds: 120
      selectPolicy: Min