System Designer

What is Kubernetes?

Kubernetes (K8s) is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. Originally developed by Google, it provides a robust foundation for running distributed systems resiliently, handling scaling and failover for your applications.

Kubernetes Architecture

Control Plane

• API Server: Central management entity
• etcd: Distributed key-value store
• Scheduler: Assigns pods to nodes
• Controller Manager: Runs controller processes

Worker Nodes

• kubelet: Node agent
• kube-proxy: Network proxy
• Container Runtime: Docker, containerd
• Pods: Running application instances

Core Kubernetes Resources

Pod

Smallest deployable unit containing one or more containers sharing network and storage.

• Shared IP address and port space
• Shared storage volumes
• Containers can communicate via localhost

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
spec:
  containers:
  - name: nginx
    image: nginx:1.20
    ports:
    - containerPort: 80

Deployment

Manages replica sets and provides declarative updates to pods with rollout and rollback capabilities.

• Rolling updates
• Rollback functionality
• Scaling operations

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.20

Service

Provides stable network endpoint for a set of pods with load balancing and service discovery.

• ClusterIP: Internal cluster access
• NodePort: External access via node ports
• LoadBalancer: Cloud provider integration

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

Cluster Metrics Calculator

Total Pods: 100

Worker Nodes: 5

Replica Count: 3

Resource Utilization: 70%

Pods/Node

Available Replicas

65%

Efficiency

Total CPU Cores

Deployment Patterns

Rolling Update

Gradually replaces old pods with new ones, ensuring zero downtime.

Blue-Green

Maintains two identical production environments, switching traffic instantly.

Canary

Releases new version to a small subset of users first.

Rolling Update Configuration

spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
      maxSurge: 1
  template:
    spec:
      containers:
      - name: app
        image: myapp:v2
        readinessProbe:
          httpGet:
            path: /health
            port: 8080

Storage & Configuration Management

ConfigMaps & Secrets

Separate configuration from application code for better portability and security.

# ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  database_url: "postgres://..."
  
# Secret
apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: Opaque
data:
  password: cGFzc3dvcmQ=

Persistent Volumes

Abstract storage resources that persist beyond pod lifecycle.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
  storageClassName: fast-ssd

Real-World Kubernetes Implementations

Spotify

Runs 150+ services on Kubernetes across multiple regions.

• Music recommendation microservices
• Auto-scaling based on user activity
• Multi-region disaster recovery

Airbnb

Migrated 1000+ microservices to Kubernetes for better scalability.

• Property search and booking services
• ML-powered pricing algorithms
• Real-time messaging platform

Uses Kubernetes to handle traffic spikes and maintain high availability.

• Comment and voting systems
• Content delivery optimization
• A/B testing infrastructure

Adopted Kubernetes for containerizing their monolithic applications.

• Image processing pipelines
• Search and recommendation engines
• User analytics platform

Test Your Knowledge

📝 Kubernetes Knowledge Quiz

1 of 6Current: 0/6

Kubernetes: Container Orchestration at Scale