Kubernetes Networking

Networking is one of the most complex aspects of Kubernetes. This lesson covers Service types, Ingress controllers, NetworkPolicies, DNS, and service discovery — the building blocks for production-grade connectivity.

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Services

A Service provides a stable endpoint for a set of pods, abstracting away pod IP changes.

Service Types

Type	Accessibility	Use Case
ClusterIP	Within the cluster only	Internal microservice communication
NodePort	External via node IP:port	Development, testing
LoadBalancer	External via cloud LB	Production external traffic
ExternalName	DNS CNAME redirect	Accessing external services

ClusterIP (Default)

apiVersion: v1
kind: Service
metadata:
  name: backend-api
spec:
  type: ClusterIP
  selector:
    app: backend-api
  ports:
    - port: 80
      targetPort: 8080
      protocol: TCP

NodePort

apiVersion: v1
kind: Service
metadata:
  name: web-app
spec:
  type: NodePort
  selector:
    app: web-app
  ports:
    - port: 80
      targetPort: 8080
      nodePort: 30080      # Accessible on every node at port 30080

LoadBalancer

apiVersion: v1
kind: Service
metadata:
  name: public-api
  annotations:
    service.beta.kubernetes.io/aws-load-balancer-type: nlb
spec:
  type: LoadBalancer
  selector:
    app: public-api
  ports:
    - port: 443
      targetPort: 8443

Headless Service (for StatefulSets)