How ingress routing works

Question

I’ve seen a few kubernetes cluster example where they have ingress class added with annotations, for example:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
 annotations:
    kubernetes.io/ingress.class: nginx
spec:
 rules:
   - host: testsvc.k8s.privatecloud.com
     http:

Also, There could be many services configured with the hosts rule like,

testsvc.k8s.privatecloud.com
testsvc1.k8s.privatecloud.com
testsvc2.k8s.privatecloud.com

How does the routing in ingress works?

Answer 1

The dns of all the host name points to the load balancer through which all the traffic is routed to the ingress controller’s nginx.

Kubernetes ingress works as proxy between the internal cluster and the external network.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: test
  annotations:
    ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: foo.bar.com
    http:
      paths:
      - path: /foo
        backend:
          serviceName: s1
          servicePort: 80
      - path: /bar
        backend:
          serviceName: s2
          servicePort: 80