Nginx ingress controller - Return 200 on root - nginx

Question

We are using the Nginx ingress controller in Azure Kubernetes Service to direct traffic to a number of .NET Apis that we run there.
All calls to this are routed via the Azure Application Gateway for WAF and DNS reasons.
Application gateway has "health probes" that hit your backend pools (which point to the external IP of our nginx ingress controller service) performing a GET at the root.
Previously we had services for each site, setup as LoadBalancer, which gave each site their own external IP address, and we pointed the backend pool to that and it worked fine.
But now we are trying to do things more securely and route all calls via the Ingress Controller... but now we have one backend pool with the ingress controller's IP address, and as there's nothing there the health probe comes back unhealthy, and the site doesn't work.
I have setup the Ingress for the site so that if a request hits the backend pool with the domain (below) it will work, but the health probe doesn't seem to do that. As it is just doing a GET on the IP address of the controller.
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: my-ingress
spec:
rules:
- host: "api.mydomain.com"
http:
paths:
- pathType: Prefix
path: /
backend:
service:
name: my-api-service
port:
number: 443
I installed the controller using the Helm chart, and I just want to be able to set it so that a GET request to that controller will just return 200 and any other request will be directed appropriately. I had tried the below for our ingress, to route a call to the root to the api (which has a 200 response at its root) but I don't think that was the right place for it, and it didn't work. It might have to be part of the Helm command to setup the Ingress controller itself.
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: my-ingress
spec:
rules:
- http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: my-api-service
port:
number: 443
- host: "api.mydomain.com"
http:
paths:
- pathType: Prefix
path: /
backend:
service:
name: my-api-service
port:
number: 443

Answer 1

The nginx ingress controller exposes a default backend /healthz endpoint which returns 200 OK. You can make your App gateway health probe to point to this endpoint.
Also, instead of using App gateway + NGINX ingress controller which require 2 hops before reaching your service, consider using Application Gateway ingress controller (AGIC).