Ingress

What is Ingress?

Ingress is the layer-7 (HTTP/HTTPS) way to expose services to the outside world. Instead of giving every service a public IP (LoadBalancer), one Ingress controller routes external traffic to the right service based on host and path.

An Ingress Resource

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

kubectl apply -f ingress.yaml
kubectl get ingress

Ingress Controllers

The Ingress resource is only a set of rules. Something must implement them - typically an nginx or Traefik controller running as a Deployment in the cluster:

kubectl get pods -n ingress-nginx

Host-Based Routing

  rules:
  - host: api.example.com
    http:
      paths:
      - path: /v1
        pathType: Prefix
        backend:
          service:
            name: api
            port:
              number: 8080

Now app.example.com and api.example.com share the same load balancer but route to different services.

Key Points

• Ingress = HTTP routing rules; an Ingress controller enforces them.
• Use Ingress instead of many LoadBalancer services to save IPs.
• HTTPS/TLS certificates are configured on the Ingress too.