1. Introduction

Kubernetes (also known as K8s) is an open-source platform designed to automate deploying, scaling, and operating application containers.

🔍 Why Kubernetes?

• Container orchestration at scale.

• Self-healing: Automatically restarts failed containers.

• Scaling: Automatically scales up/down based on traffic.

• Rolling Updates: Updates services without downtime.

• Resource Optimization: Efficient use of CPU/memory.

🔗 Core Concepts:

2. How to Download and Install Kubernetes (Local Setup)

You can set up Kubernetes using several methods. For learning purposes, the most common and easiest is Minikube.

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Option 1: Minikube (for Local Kubernetes Cluster)

🔧 Step-by-Step Installation on Windows:

You need Windows 10+, VirtualBox or WSL2, and PowerShell or Terminal.

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Install Steps:

📥 Step 1: Install kubectl (CLI to talk to Kubernetes)

bashCopyEdit# Windows - PowerShell
choco install kubernetes-cli

# macOS
brew install kubectl

# Linux (Debian/Ubuntu)
sudo apt-get update
sudo apt-get install -y kubectl

📥 Step 2: Install Minikube

bashCopyEdit# Windows
choco install minikube

# macOS
brew install minikube

# Linux
curl -LO https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube

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🚀 Step 3: Start Minikube

bashCopyEditminikube start

🔄 This downloads the required Kubernetes images and creates a local cluster using VirtualBox or Docker.

🔧 If using WSL2:

bashCopyEditminikube start --driver=docker

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🔍 Step 4: Verify Your Kubernetes Cluster

bashCopyEditkubectl version --client
kubectl get nodes
kubectl cluster-info

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✅ Option 2: kubeadm (for Real Production Setup)

If you're building a production setup on your own VMs or servers (Ubuntu preferred):

📋 Prerequisites

• 2 or more Linux servers (1 master, 1+ worker)

• Swap off (sudo swapoff -a)

• Container runtime (containerd/Docker)

📥 Installation

bashCopyEdit# On all nodes
sudo apt-get update && sudo apt-get install -y apt-transport-https ca-certificates curl

curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -

sudo bash -c 'cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF'

sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

🚀 Master Node Initialization

bashCopyEditsudo kubeadm init --pod-network-cidr=192.168.0.0/16

# After success, set up kubeconfig
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

🧩 Install CNI Plugin (example: Calico)

bashCopyEditkubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

🚀 Join Worker Nodes

Run the kubeadm join ... command shown after init on each worker node.

3. Kubernetes Architecture

Kubernetes follows a master-worker architecture, where the Control Plane (Master Node) manages the Worker Nodes.

🎯 Main Components

🔹 Control Plane Components:

🔸 Node Components:

🗂️ Cluster Layout:

[ User ] --> [ kubectl ] --> [ kube-apiserver ] --> [ etcd ]
                                      |
                     ----------------------------
                     |    |     |     |         |
              [scheduler][controller][cloud mgr]

                   --> Worker Nodes
                   --> [kubelet + container runtime + kube-proxy + pods]

4. Deploying Your First App in Kubernetes

🚀 Step-by-Step YAML for Deployment

# app-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

🌐 Exposing the App as a Service

# app-service.yaml
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  type: NodePort
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
      nodePort: 30007

🧪 Apply Deployment

kubectl apply -f app-deployment.yaml
kubectl apply -f app-service.yaml
kubectl get pods
kubectl get svc

5. Kubernetes Networking

🕸️ Pod-to-Pod Communication

• All Pods get a unique IP.

• Uses CNI plugin like Calico or Flannel.

🔌 Service Types

🔁 Ingress Controller

Used to expose HTTP/HTTPS routes with domain-level routing.

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.6.4/deploy/static/provider/cloud/deploy.yaml

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6. Kubernetes Storage

🔹 Volumes

• Volumes are attached to pods and persist data.

Example:

volumeMounts:
  - mountPath: "/data"
    name: data-volume
volumes:
  - name: data-volume
    emptyDir: {}

🔹 Persistent Volumes (PV) and Persistent Volume Claims (PVC)

# pv.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: "/mnt/data"

# pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

7. Kubernetes Security

🔐 RBAC (Role-Based Access Control)

# rbac.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: default
  name: pod-reader
rules:
- apiGroups: [""]
  resources: ["pods"]
  verbs: ["get", "watch", "list"]

# role-binding.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: read-pods
  namespace: default
subjects:
- kind: User
  name: jane
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: pod-reader
  apiGroup: rbac.authorization.k8s.io

🛡️ Secrets

apiVersion: v1
kind: Secret
metadata:
  name: db-secret
stringData:
  username: admin
  password: secret123

8. Monitoring & Logging

📊 Metrics Server

kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
kubectl top pods

📈 Prometheus + Grafana

• Use Helm chart:

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install k8s-monitor prometheus-community/kube-prometheus-stack

9. Helm (Kubernetes Package Manager)

🔧 Install Helm

curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

📦 Use a Helm Chart

helm repo add bitnami https://charts.bitnami.com/bitnami
helm install my-nginx bitnami/nginx

10. Troubleshooting

🧪 Useful Commands

kubectl get all
kubectl describe pod <pod-name>
kubectl logs <pod-name>
kubectl exec -it <pod-name> -- /bin/bash

🧹 Clean Up

kubectl delete deployment nginx-deployment
kubectl delete svc nginx-service

Summary

Kubernetes is a powerful orchestration platform. With Minikube, Helm, and YAML files, you can build and manage scalable containerized applications locally or in production.

Next Step: Learn about CI/CD integration with Kubernetes using GitHub Actions or ArgoCD.

11. References

• https://kubernetes.io/docs

• https://github.com/kubernetes

• https://helm.sh/docs

• https://prometheus.io

• https://cncf.io