Ingress & Ingress Controllers

Difficulty: Advanced

Question

What is Ingress and how does it differ from a LoadBalancer service?

Answer

A **LoadBalancer** service requires a physical cloud load balancer per service, which can be expensive.

**Ingress** is an API object that manages external access to services, typically HTTP. It provides routing rules (host-based or path-based), SSL termination, and name-based virtual hosting.

Directing traffic to Ingress requires an **Ingress Controller** (like Nginx, Traefik, or Istio) to sit at the edge of the cluster, receive all traffic, and route it internally.

**In short**: Ingress is the 'Rulebook', and Ingress Controller is the 'Traffic Cop'.

Code examples

Ingress Routing Rules

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: main-ingress
spec:
  rules:
  - host: myapp.com
    http:
      paths:
      - path: /api
        pathType: Prefix
        backend:
          service:
            name: api-service
            port:
              number: 80
      - path: /
        pathType: Prefix
        backend:
          service:
            name: frontend-service
            port:
              number: 80

This single Ingress object routes traffic to different services based on the URL path.

Key points

• Ingress works at Layer 7 (HTTP/S), whereas Services mostly work at Layer 4 (TCP/UDP).

Concepts covered

Ingress, Reverse Proxy, Nginx Ingress, SSL Termination