Load Balancer vs Ingress: Key Differences Explained скачать в хорошем качестве

Load Balancer vs Ingress: Key Differences Explained

#devopsengineer #devopsmadeeasy #loadbalancer #ingress A Load Balancer is a network component that: • Distributes incoming traffic • Across multiple backend targets • To improve availability, scalability, and fault tolerance Works At • Layer 4 (TCP/UDP) → Network Load Balancer • Layer 7 (HTTP/HTTPS) → Application Load Balancer ________________________________________ Load Balancer Diagram (Cloud / Kubernetes) User Requests | v +------------------+ | Load Balancer | +------------------+ | | v v +--------+ +--------+ | Pod 1 | | Pod 2 | +--------+ +--------+ • LB knows nothing about URLs • It just forwards traffic • Health checks decide which backend is alive • Often cloud-managed (AWS ELB, Azure LB, GCP LB) ________________________________________ Kubernetes Example apiVersion: v1 kind: Service metadata: name: app-service spec: type: LoadBalancer What happens: • Kubernetes asks cloud provider • A real cloud LB is created • Each Service → one LB Cost implication: Multiple services = multiple LBs ________________________________________ What is Ingress? Ingress is a Kubernetes-native HTTP routing layer that: • Manages external HTTP/HTTPS access • Routes traffic based on rules • Works on top of a Load Balancer Important: Ingress is NOT a load balancer by itself ________________________________________ Ingress Architecture Diagram (Very Important) User | v +------------------+ | Cloud LoadBalancer| +------------------+ | v +------------------+ | Ingress Controller| | (NGINX / Traefik) | +------------------+ | | v v +---------+ +---------+ | Service | | Service | | A | | B | +---------+ +---------+ ________________________________________ Key Explanation • Ingress needs a Load Balancer • LB exposes the cluster • Ingress Controller does: o URL routing o Host-based routing o SSL termination o Rewrites, redirects ________________________________________ Ingress Example apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: app-ingress spec: rules: host: myapp.com http: paths: path: /api pathType: Prefix backend: service: name: api-service port: number: 80 ________________________________________ Traffic Flow Comparison (SUPER IMPORTANT FOR CLARITY) Load Balancer Traffic Flow Client → Load Balancer → Service → Pod Ingress Traffic Flow Client → Load Balancer → Ingress Controller → Service → Pod ________________________________________ Feature Comparison Table (Great for Slides) Feature Load Balancer Ingress OSI Layer L4 / L7 L7 only URL Routing No Yes Host-based routing No Yes SSL Termination Limited Advanced Cost High Lower Kubernetes Native Service Resource Scalability Per service Centralized ________________________________________ Real-World Scenario (Interview) Without Ingress • 10 microservices • Each needs public access • Result: o 10 Load Balancers o High cost o Hard to manage With Ingress • 1 Load Balancer • 1 Ingress Controller • Routing handled via rules /login → auth-service /cart → cart-service /order → order-service ________________________________________ When to Use Load Balancer ONLY Use Load Balancer when: • Non-HTTP traffic (TCP, gRPC) • Simple setup • One service exposed • Quick POC Example: • Database proxy • Game servers • MQTT brokers ________________________________________ When to Use Ingress (Most Production Systems) Use Ingress when: • Multiple HTTP services • Need SSL, auth, routing • Cost optimization • Central traffic control ________________________________________ Common Myths “Ingress replaces Load Balancer” No — Ingress uses a Load Balancer “Ingress is only for Kubernetes” Correct — and that’s why it’s powerful “Ingress is optional” In production → almost mandatory ________________________________________ Cloud-Specific Mapping Cloud Load Balancer Ingress Controller AWS ALB / NLB ALB Ingress / NGINX Azure Azure LB AGIC / NGINX GCP Cloud LB GCE Ingress ________________________________________