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KEDA — Event-Driven Autoscaling on Azure

KEDA (Kubernetes Event-Driven Autoscaling) extends the Kubernetes HPA to scale workloads based on external metrics — Azure Service Bus queue depth, Event Hubs lag, Azure Monitor metrics, or any custom source.

Installing KEDA​

helm repo add kedacore https://kedacore.github.io/charts
helm repo update

helm install keda kedacore/keda \
  --namespace keda \
  --create-namespace \
  --version 2.13.0 \
  --set watchNamespace="" \
  --set operator.replicaCount=2

Scale on Azure Service Bus​

kubernetes/keda/payments-worker-scaler.yaml
apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: payments-worker
  namespace: team-payments
spec:
  scaleTargetRef:
    name: payments-worker
  pollingInterval:  15
  cooldownPeriod:  120
  minReplicaCount: 1
  maxReplicaCount: 50
  triggers:
    - type: azure-servicebus
      metadata:
        queueName: payment-events
        namespace: devopsgenie-production
        # Scale 1 replica per 20 messages in the queue
        messageCount: "20"
      authenticationRef:
        name: keda-service-bus-auth
---
# TriggerAuthentication using Workload Identity
apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: keda-service-bus-auth
  namespace: team-payments
spec:
  podIdentity:
    provider: azure-workload
    identityId: "<MANAGED_IDENTITY_CLIENT_ID>"

Scale on Azure Event Hubs​

triggers:
  - type: azure-event-hub
    metadata:
      eventHubName: telemetry-events
      eventHubNamespace: devopsgenie-production
      consumerGroup: payments-consumer
      unprocessedEventThreshold: "100"
    authenticationRef:
      name: keda-eventhub-auth

Scale on Azure Monitor Metrics​

triggers:
  - type: azure-monitor
    metadata:
      resourceURI: /subscriptions/<SUB>/resourceGroups/<RG>/providers/Microsoft.Sql/servers/<SERVER>/databases/<DB>
      tenantId: "<TENANT_ID>"
      subscriptionId: "<SUB_ID>"
      resourceGroupName: devopsgenie-production
      metricName: cpu_percent
      targetValue: "70"
      metricAggregationType: Average
    authenticationRef:
      name: keda-azure-monitor-auth

Verifying KEDA​

# Check ScaledObject status
kubectl get scaledobject payments-worker -n team-payments

# Describe for events and status
kubectl describe scaledobject payments-worker -n team-payments

# Watch replicas change in response to queue depth
kubectl get pods -n team-payments -l app=payments-worker --watch