Introduction to Kubernetes

Comprehensive introduction to Kubernetes (K8s) container orchestration platform, covering core concepts, architecture, and why it

Kubernetes (K8s) is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. Originally designed by Google and now maintained by the Cloud Native Computing Foundation (CNCF), it has become the industry standard for running containers in production.

Why Kubernetes?

┌─────────────────────────────────────────────────────────────┐ │ DOCKER ALONE vs KUBERNETES ORCHESTRATION │ │ │ │ WITHOUT KUBERNETES: WITH KUBERNETES: │ │ (Manual management) (Automated orchestration) │ │ │ │ • How many containers? • Desired state: 5 replicas │ │ • Which server has space? • K8s schedules automatically │ │ • What if one crashes? • Self-healing (auto restart) │ │ • How to update? • Rolling updates │ │ • How to load balance? • Built-in service discovery │ │ • How to scale? • Auto-scaling (HPA) │ │ • Where are secrets? • Secret management │ │ • How to rollback? • One-command rollback │ │ │ │ You manage everything K8s manages everything │ └─────────────────────────────────────────────────────────────┘

Kubernetes Architecture

┌─────────────────────────────────────────────────────────────┐ │ KUBERNETES CLUSTER │ │ │ │ ┌─────────────────────────────────────────────────────┐ │ │ │ CONTROL PLANE (Master) │ │ │ │ ┌──────────┐ ┌──────────┐ ┌───────────────────┐ │ │ │ │ │API Server│ │Scheduler │ │Controller Manager │ │ │ │ │ └──────────┘ └──────────┘ └───────────────────┘ │ │ │ │ ┌──────────────────────────────────────────────┐ │ │ │ │ │ etcd (cluster state) │ │ │ │ │ └──────────────────────────────────────────────┘ │ │ │ └─────────────────────────────────────────────────────┘ │ │ │ │ │ ┌────────────────────────┼────────────────────────────┐ │ │ │ WORKER NODES │ │ │ │ │ │ │ │ │ ┌──────────────┐ ┌──────────────┐ │ │ │ │ │ Node 1 │ │ Node 2 │ ... │ │ │ │ │ ┌──────────┐ │ │ ┌──────────┐ │ │ │ │ │ │ │ kubelet │ │ │ │ kubelet │ │ │ │ │ │ │ ├──────────┤ │ │ ├──────────┤ │ │ │ │ │ │ │kube-proxy│ │ │ │kube-proxy│ │ │ │ │ │ │ ├──────────┤ │ │ ├──────────┤ │ │ │ │ │ │ │Container │ │ │ │Container │ │ │ │ │ │ │ │ Runtime │ │ │ │ Runtime │ │ │ │ │ │ │ ├──────────┤ │ │ ├──────────┤ │ │ │ │ │ │ │┌──┐ ┌──┐│ │ │ │┌──┐ ┌──┐│ │ │ │ │ │ │ ││P1│ │P2││ │ │ ││P3│ │P4││ │ │ │ │ │ │ │└──┘ └──┘│ │ │ │└──┘ └──┘│ │ │ │ │ │ │ └──────────┘ │ │ └──────────┘ │ │ │ │ │ └──────────────┘ └──────────────┘ │ │ │ └─────────────────────────────────────────────────────┘ │ └─────────────────────────────────────────────────────────────┘ P = Pod (smallest deployable unit)

Core Concepts

Concept	Description
Pod	Smallest deployable unit; one or more containers
Deployment	Manages pod replicas and rolling updates
Service	Stable network endpoint for a set of pods
Namespace	Virtual cluster for resource isolation
ConfigMap	External configuration storage
Secret	Sensitive data storage (base64 encoded)
Ingress	External HTTP/HTTPS routing
Volume	Persistent storage for pods

Getting Started with kubectl

bash example

# Install kubectl
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
chmod +x kubectl && sudo mv kubectl /usr/local/bin/

# Cluster info
kubectl cluster-info
kubectl get nodes

# Deploy an application
kubectl create deployment nginx --image=nginx:1.25 --replicas=3

# Expose it as a service
kubectl expose deployment nginx --port=80 --type=LoadBalancer

# View resources
kubectl get pods
kubectl get services
kubectl get deployments

# Scale
kubectl scale deployment nginx --replicas=5

# View logs
kubectl logs -f deployment/nginx

# Delete resources
kubectl delete deployment nginx
kubectl delete service nginx

Deploying with YAML

yaml example

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  labels:
    app: web
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: web
        image: my-web-app:v2.0
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "128Mi"
            cpu: "250m"
          limits:
            memory: "256Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 10
          periodSeconds: 30
---
apiVersion: v1
kind: Service
metadata:
  name: web-app-service
spec:
  selector:
    app: web
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer

bash example

# Apply the configuration
kubectl apply -f deployment.yaml

# Check rollout status
kubectl rollout status deployment/web-app

# Update image (rolling update)
kubectl set image deployment/web-app web=my-web-app:v3.0

# Rollback
kubectl rollout undo deployment/web-app

Managed Kubernetes Services

Service	Provider	Description
EKS	AWS	Elastic Kubernetes Service
AKS	Azure	Azure Kubernetes Service
GKE	Google	Google Kubernetes Engine
DOKS	DigitalOcean	Managed K8s

bash example

# Create EKS cluster
eksctl create cluster \
  --name production \
  --region us-east-1 \
  --nodegroup-name workers \
  --node-type t3.medium \
  --nodes 3

# Create GKE cluster
gcloud container clusters create production \
  --zone us-central1-a \
  --num-nodes 3 \
  --machine-type e2-standard-4

Interview Questions

What is Kubernetes and what problem does it solve?

Kubernetes is a container orchestration platform that automates deployment, scaling, and management of containerized applications. It solves the problem of running containers reliably at scale — handling scheduling, self-healing, load balancing, rolling updates, and service discovery automatically.

Explain the Kubernetes architecture.

Control Plane: API Server (entry point), Scheduler (assigns pods to nodes), Controller Manager (maintains desired state), etcd (cluster state store). Worker Nodes: kubelet (runs pods), kube-proxy (networking), Container Runtime (runs containers).

What is a Pod in Kubernetes?

A Pod is the smallest deployable unit — it wraps one or more tightly-coupled containers that share network (same IP, communicate via localhost) and storage. Usually one main container per pod, with optional sidecar containers for logging or proxying.

How does Kubernetes handle application updates?

Through rolling updates: K8s gradually replaces old pods with new ones, ensuring zero downtime. It creates new pods with the updated image, waits for them to be healthy, then terminates old pods. If issues arise, you can rollback instantly.

What are the benefits of managed Kubernetes (EKS, AKS, GKE)?

The provider manages the control plane (API server, etcd, scheduler) — handling upgrades, patches, and high availability. You only manage worker nodes and workloads. This reduces operational burden significantly compared to self-managed Kubernetes.

Why Kubernetes?

Kubernetes Architecture

Core Concepts

Concept	Description
Pod	Smallest deployable unit; one or more containers
Deployment	Manages pod replicas and rolling updates
Service	Stable network endpoint for a set of pods
Namespace	Virtual cluster for resource isolation
ConfigMap	External configuration storage
Secret	Sensitive data storage (base64 encoded)
Ingress	External HTTP/HTTPS routing
Volume	Persistent storage for pods

Getting Started with kubectl

bash example

# Install kubectl
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
chmod +x kubectl && sudo mv kubectl /usr/local/bin/

# Cluster info
kubectl cluster-info
kubectl get nodes

# Deploy an application
kubectl create deployment nginx --image=nginx:1.25 --replicas=3

# Expose it as a service
kubectl expose deployment nginx --port=80 --type=LoadBalancer

# View resources
kubectl get pods
kubectl get services
kubectl get deployments

# Scale
kubectl scale deployment nginx --replicas=5

# View logs
kubectl logs -f deployment/nginx

# Delete resources
kubectl delete deployment nginx
kubectl delete service nginx

Deploying with YAML

yaml example

# deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
  labels:
    app: web
spec:
  replicas: 3
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: web
        image: my-web-app:v2.0
        ports:
        - containerPort: 8080
        resources:
          requests:
            memory: "128Mi"
            cpu: "250m"
          limits:
            memory: "256Mi"
            cpu: "500m"
        livenessProbe:
          httpGet:
            path: /health
            port: 8080
          initialDelaySeconds: 10
          periodSeconds: 30
---
apiVersion: v1
kind: Service
metadata:
  name: web-app-service
spec:
  selector:
    app: web
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer

bash example

# Apply the configuration
kubectl apply -f deployment.yaml

# Check rollout status
kubectl rollout status deployment/web-app

# Update image (rolling update)
kubectl set image deployment/web-app web=my-web-app:v3.0

# Rollback
kubectl rollout undo deployment/web-app

Managed Kubernetes Services

Service	Provider	Description
EKS	AWS	Elastic Kubernetes Service
AKS	Azure	Azure Kubernetes Service
GKE	Google	Google Kubernetes Engine
DOKS	DigitalOcean	Managed K8s

bash example

# Create EKS cluster
eksctl create cluster \
  --name production \
  --region us-east-1 \
  --nodegroup-name workers \
  --node-type t3.medium \
  --nodes 3

# Create GKE cluster
gcloud container clusters create production \
  --zone us-central1-a \
  --num-nodes 3 \
  --machine-type e2-standard-4

Interview Questions

What is Kubernetes and what problem does it solve?

Explain the Kubernetes architecture.

What is a Pod in Kubernetes?

How does Kubernetes handle application updates?

What are the benefits of managed Kubernetes (EKS, AKS, GKE)?

Introduction to Kubernetes

Why Kubernetes?

Kubernetes Architecture

Core Concepts

Getting Started with kubectl

Deploying with YAML

Managed Kubernetes Services

Interview Questions

Continue learning this concept

Introduction to Kubernetes

Why Kubernetes?

Kubernetes Architecture

Core Concepts

Getting Started with kubectl

Deploying with YAML

Managed Kubernetes Services

Interview Questions

Continue learning this concept