Welcome to Stack Simplify

Author: Kalyan Reddy Daida

15-EKS-HPA-Horizontal-Pod-Autoscaler/README.md

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+# EKS - Horizontal Pod Autoscaling (HPA)
+
+## Step-01: Introduction
+- What is Horizontal Pod Autoscaling?
+- How HPA Works?
+- How HPA configured?
+
+## Step-02: Install Metrics Server
+```
+# Verify if Metrics Server already Installed
+kubectl -n kube-system get deployment/metrics-server
+
+# Install Metrics Server
+kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/download/v0.3.6/components.yaml
+
+# Verify
+kubectl get deployment metrics-server -n kube-system
+```
+
+## Step-03: Deploy our Application
+```
+# Deploy
+kubectl apply -f kube-manifests/
+
+# List Pods, Deploy & Service
+kubectl get pod,svc,deploy
+
+# Access Application
+kubectl get nodes -o wide
+http://<Worker-Node-Public-IP>:31231
+```
+
+## Step-04: Create a Horizontal Pod Autoscaler resource for the "hpa-demo-deployment" 
+- This command creates an autoscaler that targets 50 percent CPU utilization for the deployment, with a minimum of one pod and a maximum of ten pods. 
+- When the average CPU load is below 50 percent, the autoscaler tries to reduce the number of pods in the deployment, to a minimum of one. 
+- When the load is greater than 50 percent, the autoscaler tries to increase the number of pods in the deployment, up to a maximum of ten
+```
+# Template
+kubectl autoscale deployment <deployment-name> --cpu-percent=50 --min=1 --max=10
+
+# Replace
+kubectl autoscale deployment hpa-demo-deployment --cpu-percent=50 --min=1 --max=10
+
+# Describe HPA
+kubectl describe hpa/hpa-demo-deployment 
+
+# List HPA
+kubectl get horizontalpodautoscaler.autoscaling/hpa-demo-deployment 
+```
+
+## Step-05: Create the load & Verify how HPA is working
+```
+# Generate Load
+kubectl run --generator=run-pod/v1 apache-bench -i --tty --rm --image=httpd -- ab -n 500000 -c 1000 http://hpa-demo-service-nginx.default.svc.cluster.local/ 
+
+# List all HPA
+kubectl get hpa
+
+# List specific HPA
+kubectl get hpa hpa-demo-deployment 
+
+# Describe HPA
+kubectl describe hpa/hpa-demo-deployment 
+
+# List Pods
+kubectl get pods
+```
+
+## Step-07: Cooldown / Scaledown
+- Default cooldown period is 5 minutes. 
+- Once CPU utilization of pods is less than 50%, it will starting terminating pods and will reach to minimum 1 pod as configured.
+
+## Step-08: Imperative vs Declarative for HPA
+- From Kubernetes v1.18 onwards, we have a declarative way of defining HPA policies using `behavior` object in yaml.
+- **Support for configurable scaling behavior**
+  - Starting from v1.18 the v2beta2 API allows scaling behavior to be configured through the HPA behavior field. 
+  - Behaviors are specified separately for scaling up and down in scaleUp or scaleDown section under the behavior field
+```yml
+behavior:
+  scaleDown:
+    stabilizationWindowSeconds: 300
+    policies:
+    - type: Percent
+      value: 100
+      periodSeconds: 15
+  scaleUp:
+    stabilizationWindowSeconds: 0
+    policies:
+    - type: Percent
+      value: 100
+      periodSeconds: 15
+    - type: Pods
+      value: 4
+      periodSeconds: 15
+    selectPolicy: Max
+```
+- **Reference:** Select V1.18 from top right corner on Kubernetes website for V1.18 documentation
+  -  https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale/
+
+## Step-06: Clean-Up
+```
+# Delete HPA
+kubectl delete hpa hpa-demo-deployment
+
+# Delete Deployment & Service
+kubectl delete -f V1-HPA/01-kubenginx-Deployment-NodePort-Service-for-HPA-Demo.yml 
+```
+
+## Referencess
+### Metrics Server Releases
+- https://github.com/kubernetes-sigs/metrics-server/releases
+
+### Horizontal Pod Autoscaling - Scale based on many type of metrics
+- https://v1-16.docs.kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/

15-EKS-HPA-Horizontal-Pod-Autoscaler/kube-manifests/01-kubenginx-Deployment-NodePort-Service-for-HPA-Demo.yml

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+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: hpa-demo-deployment
+  labels:
+    app: hpa-nginx
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: hpa-nginx
+  template:
+    metadata:
+      labels:
+        app: hpa-nginx
+    spec:
+      containers:
+      - name: hpa-nginx
+        image: stacksimplify/kubenginx:1.0.0
+        ports:
+        - containerPort: 80
+        resources:
+          requests:
+            memory: "128Mi"
+            cpu: "100m"
+          limits:
+            memory: "500Mi"
+            cpu: "200m"          
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: hpa-demo-service-nginx
+  labels:
+    app: hpa-nginx
+spec:
+  type: NodePort
+  selector:
+    app: hpa-nginx
+  ports:
+  - port: 80
+    targetPort: 80
+    nodePort: 31231
+