# Autoscaling based on custom metrics

### Deploy an app with custom metrics

cat <<EOF | kubectl apply -f -
kind: ServiceMonitor
apiVersion: monitoring.coreos.com/v1
metadata:
  name: sample-app
  labels:
    app: sample-app
spec:
  selector:
    matchLabels:
      app: sample-app
  endpoints: 
  - port: http
    interval: 30s
---
apiVersion: v1
kind: Service
metadata:
  name: sample-app
  labels:
    app: sample-app
spec:
  ports:
  - name: http
    port: 8080
    targetPort: 8080
  selector:
    app: sample-app
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: sample-app
  labels:
    app: sample-app
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sample-app
  template:
    metadata:
      labels:
        app: sample-app
    spec:
      containers:
      - image: luxas/autoscale-demo:v0.1.2
        name: metrics-provider
        ports:
        - name: http
          containerPort: 8080
EOF

### Create KEDA ScaledObject

cat <<EOF | kubectl apply -f -
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: prometheus-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: sample-app
  pollingInterval:  30
  cooldownPeriod:   60
  minReplicaCount:  1
  maxReplicaCount:  10   
  advanced:
    horizontalPodAutoscalerConfig:
      behavior:                                      
        scaleDown:
          stabilizationWindowSeconds: 60 
          policies:
          - type: Percent
            value: 100
            periodSeconds: 15
        scaleUp:
          stabilizationWindowSeconds: 0 
  triggers:
  - type: prometheus
    metadata:
      serverAddress: http://prometheus-operated.kubesphere-monitoring-system.svc:9090
      metricName: http_requests_total
      threshold: '100'
      query: sum(rate(http_requests_total{service="sample-app"}[2m]))
EOF

### Check custom metrics exposed

kubectl get --raw "/apis/external.metrics.k8s.io/v1beta1" | jq .
kubectl get scaledobjects.keda.sh prometheus-scaledobject -o jsonpath={.metadata.labels}
kubectl get --raw "/apis/external.metrics.k8s.io/v1beta1/namespaces/default/prometheus-http---prometheus-operated-kubesphere-monitoring-system-svc-9090-http_requests_total?labelSelector=scaledobject.keda.sh/name=prometheus-scaledobject" | jq .

### Autoscaling based on custom metrics

## watch the sample-app to scale
watch kubectl get deployment sample-app

## Put some load on the app
kubectl run utils -it --image arunvelsriram/utils bash
wget https://hey-release.s3.us-east-2.amazonaws.com/hey_linux_amd64
mv hey_linux_amd64 hey && chmod +x hey
./hey -c 20 -n 100000000 http://sample-app.default.svc:8080/metrics