An ingress in kubernetes is required if you want to expose a web server to the network (outside the kubernetes cluster).
https://kubernetes.github.io/ingress-nginx/
Installing the ingress-nginx ingress is as easy as applying the manifest of its deployment:
kubectl apply -f "https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v1.10.1/deploy/static/provider/cloud/deploy.yaml"