I find some usecases of k8s in production which work with the Public Cloud will put a LoadBalancer type of Service in front of the Nginx Ingress. (You can find an example from the below yaml.)
As I known, ingress can be used to expose the internal servcie to the public, so what's the point to put a loadbalancer in front of the ingress? Can I delete that service?
apiVersion: v1
kind: Service
metadata:
annotations:
labels:
helm.sh/chart: ingress-nginx-3.27.0
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/instance: ingress-nginx
app.kubernetes.io/version: 0.45.0
app.kubernetes.io/managed-by: Helm
app.kubernetes.io/component: controller
kubernetes.io/elb.class: union
name: ingress-nginx-controller
namespace: ingress-nginx
spec:
type: LoadBalancer
loadBalancerIP: xxx.xxx.xxx.xxx
externalTrafficPolicy: Cluster
ports:
- name: http
port: 80
protocol: TCP
targetPort: http
- name: https
port: 443
protocol: TCP
targetPort: https
selector:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/instance: ingress-nginx
app.kubernetes.io/component: controllerBecause the Ingress Controller itself is, in this case, running inside a Pod so it needs to be exposed to the internet like anything else running in Pod. Some Ingress Controllers have the actual proxy running externally, like the AWS ALB one. But Nginx is just running inside the container like normal.
...so what's the point to put a loadbalancer in front of the ingress?This way allows you to take advantage of the cloud provider LB facilities (eg. multi-az etc), then with Ingress you can further control routing using path or name-based virtual host for services in the cluster.
Can I delete that service?Ingress doesn't do port mapping or pods selection, and you can't resolve an Ingress name with DNS.