Ingress & Ingress Controllers

While a LoadBalancer Service is simple, it's expensive (one per Service). Ingress allows you to use one entry point (one IP/Load Balancer) to route traffic to dozens of internal Services based on paths or hostnames.

1. How Ingress Works

You need two things:

1. Ingress Controller: The actual server (like Nginx, Traefik, or HAProxy) that handles the traffic.
2. Ingress Resource: The YAML rules that tell the controller where to send the traffic.

2. Creating an Ingress Resource

ingress.yaml:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: main-ingress
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: myapp.com
    http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 8080
      - path: /web
        pathType: Prefix
        backend:
          service:
            name: web-service
            port:
              number: 80

Apply and Verify

Action:

kubectl apply -f ingress.yaml
kubectl get ingress

Result:

NAME           CLASS    HOSTS       ADDRESS          PORTS   AGE
main-ingress   nginx    myapp.com   203.0.113.10     80      30s

(Traffic to http://myapp.com/api now goes to api-service, and http://myapp.com/web goes to web-service!)

3. SSL/TLS Termination

Ingress can also handle your HTTPS certificates, so your backend services don't have to.

Action (Manifest snippet):

spec:
  tls:
  - hosts:
      - myapp.com
    secretName: myapp-tls-secret

Summary

• Ingress Controller: The traffic-handling software (Nginx, Traefik).
• Ingress Resource: Your routing rules (YAML).
• Path-Based Routing: /api vs /web.
• Host-Based Routing: api.myapp.com vs shop.myapp.com.
• SSL Termination: Decrypts HTTPS at the entry point.