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GCP Google Kubernetes Engine Horizontal Pod Autoscaling

Step-01: Introduction

  • Implement a Sample Demo with Horizontal Pod Autoscaler

Step-02: YAML Manifests: Review Kubernetes Manifests

  • Folder: p3-k8sresources-yaml-autoscaler-v2
  • Primarily review HorizontalPodAutoscaler Resource in file p3-k8sresources-yaml-autoscaler-v2/03-kubernetes-hpa.yaml
  • 01-kubernetes-deployment.yaml
  • 02-kubernetes-cip-service.yaml
  • 03-kubernetes-hpa.yaml 
    apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: myapp1-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: myapp1-deployment
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 30

Step-03: Project-4: p4-k8sresources-terraform-manifests: Terraform Manifests

Step-03-01: NO changes to following manifests

  • Folder: p3-k8sresources-terraform-manifests
  • c2-01-variables.tf
  • c2-02-local-values.tf
  • c3-01-remote-state-datasource.tf
  • c3-02-providers.tf
  • c4-kubernetes-deployment.tf
  • terraform.tfvars

Step-03-02: c1-versions.tf

  • Update your Cloud Storage Bucket 
      backend "gcs" {
    bucket = "terraform-on-gcp-gke"
    prefix = "dev/k8s-demo1"    
  }

Step-03-03: c5-kubernetes-clusterip-service.tf

# Kubernetes Service Manifest (Type: Load Balancer)
resource "kubernetes_service_v1" "cip_service" {
  metadata {
    name = "myapp1-cip-service"
  }
  spec {
    selector = {
      app = kubernetes_deployment_v1.myapp1.spec[0].selector[0].match_labels.app
    }
    port {
      name        = "http"
      port        = 80
      target_port = 80
    }
    type = "ClusterIP"
  }
}

Step-03-04: c6-kubernetes-hpa.tf

# Resource: Horizontal Pod Autoscaler V2
resource "kubernetes_horizontal_pod_autoscaler_v2" "cpu_autoscaler" {
  metadata {
    name = "myapp1-hpa" 
  }

  spec {
    min_replicas = 1
    max_replicas = 10

    scale_target_ref {
      api_version = "apps/v1"
      kind        = "Deployment"
      name        = kubernetes_deployment_v1.myapp1.metadata[0].name 
    }
    metric {
      type = "Resource"
      resource {
        name = "cpu"
        target {
          type               = "Utilization"
          average_utilization = 30
        }
      }
    }
  }
}

Step-03-05: Execute Terraform Commands

# Change Directory
cd p4-k8sresources-terraform-manifests

# Terraform Initialize
terraform init

# Terraform Validate
terraform validate

# Terraform plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

Step-03-06: Verify Kubernetes Resources

# List Pods
kubectl get pods
Observation: 
1. Currently only 1 pod is running

# List HPA
kubectl get hpa

# Run Load Test (New Terminal)
kubectl run -i --tty load-generator --rm --image=busybox --restart=Never -- /bin/sh -c "while sleep 0.01; do wget -q -O- http://myapp1-cip-service; done"

# List Pods (SCALE UP EVENT)
kubectl get pods
Observation:
1. New pods will be created to reduce the CPU spikes

# kubectl top command
kubectl top pod

# List HPA (after few mins - approx 3 to 5 mins)
kubectl get hpa --watch

# List Pods (SCALE IN EVENT)
kubectl get pods
Observation:
1. Only 1 pod should be running when there is no load on the workloads

Step-04: Clean-Up

# Delete Load Generator Pod which is in Error State
kubectl delete pod load-generator

# Change Directory
cd p4-k8sresources-terraform-manifests

# Terraform Destroy
terraform apply -destroy -auto-approve

References

  • https://cloud.google.com/kubernetes-engine/docs/concepts/horizontalpodautoscaler
  • https://cloud.google.com/kubernetes-engine/docs/how-to/horizontal-pod-autoscaling

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