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Kubernetes Ingress

What is Ingress?​

  • Collection of rules that manage inbound connections to cluster Services
  • Decouples routing rules from applications
  • Centralizes rules management

Ingress Diagram

Problem Solved​

  • Services have routing rules tied to them
  • Many rules because many Services
  • Need to update application without worrying about external access

Ingress Features​

  • TLS (Transport Layer Security)
  • Name-based virtual hosting
  • Fanout routing
  • Load balancing
  • Custom rules

How it Works​

  • Users connect to Ingress endpoint (not directly to Service)
  • Ingress forwards request to desired Service
  • Configures Layer 7 HTTP/HTTPS load balancer

Example Use Case​

  • blue.example.com → forwards to webserver-blue-svc
  • green.example.com → forwards to webserver-green-svc
  • Both go through same Ingress endpoint

Ingress Types​

Name-Based Virtual Hosting​

  • Different hostnames route to different services
  • Same Ingress endpoint handles multiple domains

Fanout Routing​

  • Different paths on same host route to different services
  • example.com/blue → webserver-blue-svc
  • example.com/green → webserver-green-svc

Key Concept​

  • Ingress resource - Only defines routing rules
  • Ingress Controller - Does actual request forwarding
  • Controller role - Reverse proxy that implements the rules

Ingress Controller​

  • Application that watches API server for Ingress resource changes
  • Updates Layer 7 Load Balancer accordingly
  • Also known as: Controllers, Ingress Proxy, Service Proxy, Reverse Proxy

Common Ingress Controllers​

  • GCE L7 Load Balancer Controller
  • AWS Load Balancer Controller
  • Nginx Ingress Controller
  • Contour
  • HAProxy Ingress
  • Istio Ingress
  • Kong
  • Traefik

Configuration Requirements​

  • Must specify ingressClassName in Ingress resource
  • Example: spec.ingressClassName: nginx
  • May need controller-specific annotations for advanced features

Minikube Setup​

minikube addons enable ingress

Practical Examples​

Basic Name-Based Virtual Hosting​

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: virtual-host-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: blue.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: webserver-blue-svc
            port:
              number: 80
  - host: green.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: webserver-green-svc
            port:
              number: 80

Fanout Routing Example​

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: fanout-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  ingressClassName: nginx
  rules:
  - host: example.com
    http:
      paths:
      - path: /blue
        pathType: Prefix
        backend:
          service:
            name: webserver-blue-svc
            port:
              number: 80
      - path: /green
        pathType: Prefix
        backend:
          service:
            name: webserver-green-svc
            port:
              number: 80

TLS/HTTPS Ingress​

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: tls-ingress
spec:
  ingressClassName: nginx
  tls:
  - hosts:
    - secure.example.com
    secretName: tls-secret
  rules:
  - host: secure.example.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

Common Commands​

Deploy Ingress Resource​

# Create Ingress from file
kubectl create -f virtual-host-ingress.yaml
kubectl apply -f virtual-host-ingress.yaml

View Ingress Resources​

# List all Ingress resources
kubectl get ingress
kubectl get ing

# Detailed view
kubectl get ingress -o wide
kubectl describe ingress virtual-host-ingress

Access Services Using Ingress​

  • Access services using configured URLs
  • Example: blue.example.com and green.example.com

Local Testing Setup (Minikube)​

# Get Minikube IP
minikube ip

# Edit hosts file
sudo vim /etc/hosts

# Add entries (replace with your Minikube IP)
192.168.99.100 blue.example.com green.example.com

Troubleshooting Commands​

# Check Ingress Controller pods
kubectl get pods -n ingress-nginx

# Check Ingress Controller logs
kubectl logs -n ingress-nginx deployment/ingress-nginx-controller

# Test connectivity
curl -H "Host: blue.example.com" http://MINIKUBE_IP