FHIR server cannot be accessed through an NGINX ingress on AKS.

[Alan-Kuan]

I deployed the whole service on AKS on Azure Stack HCI. The FHIR Server and the MS SQL Server were provisioned successfully. However, after I added an NGINX ingress that redirected requests from the ingress controller to the FHIR Service, I found that I could not access the API through the ingress controller. Later, I changed the service type of the FHIR Service into LoadBalancer instead of ClusterIP, and this time, I could access the FHIR Service directly.

I wonder how could I make my previous setup work?

This is the result.

And this is the config of the ingress.

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-fhir
  namespace: alan-fhir
  annotations:
    # CORS
    nginx.ingress.kubernetes.io/enable-cors: "true"
    nginx.ingress.kubernetes.io/cors-allow-origin: "*"
    nginx.ingress.kubernetes.io/cors-allow-methods: "*"
    nginx.ingress.kubernetes.io/cors-allow-headers: "Origin,X-Requested-With,Content-Type,Authorization,Accept,Prefer"
    nginx.ingress.kubernetes.io/cors-max-age: "1440"
spec:
  ingressClassName: nginx
  rules:
  - host: 10.100.172.42.nip.io
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: fhir-server
            port:
              number: 80

[Alan-Kuan]

I found the problem. The hostname I specified in the config should be resolved to the address of the NGINX controller's, but not the one of the FHIR Service's.
I should realize this point sooner...