how to provide inbound access from public internet to an app hosted in an Azure private kubernetes cluster - azure

Question

I deployed an application in an Azure K8S cluster, using NGINX as gateway, with a public static IP, based on AKS & PUBLIC-IP and on AKS & NGINX.
Now I need to deploy the application in an Azure private cluster, ie, running in a private vnet (see CREATE PRIVATE AKS); attempting to assign a public static IP to NGINX does not work, which can be expected as the load-balancer expects a private IP, not a public IP.
How can I provide inbound access to my app hosted in a private cluster, using NGINX and a public static IP?

Answer 1

Hi you have two ways two achieve that...Depending on your needs (and Azure costs...):
1-Use Azure Application Gateway. For myself I use Terraform. And here you can the see official documentation regarding internal IP address.
Now you can use this one as your new Ingress (and get rid of NGINX) like:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: guestbook
annotations:
kubernetes.io/ingress.class: azure/application-gateway
spec:
rules:
- http:
paths:
- backend:
serviceName: frontend
servicePort: 80
Or you could use NGINX internally as your ingress like explained on option 2.
2- First you must have a Public IP with a Load Balancer associated with it.The backend from that LB must be up to your needs.
But here is the trick...Do not create NGINX with that public IP but with an internal IP and an internal load balancer, you can see how to do that in the following url:
https://learn.microsoft.com/en-us/azure/aks/ingress-internal-ip
And the important thing you must do is the nginx ovveride on the helm parameters:
controller:
service:
loadBalancerIP: 10.240.0.42
annotations:
service.beta.kubernetes.io/azure-load-balancer-internal: "true"
Of course the internal VNET must be created an the load balancer IP must be a correct one.
And the final trick now that you have NGINX listening behind a private IP is to verify your traffic from the Public IP is redirected to that internal VNET...Of course it depends on how you have infrastructure setup behind that LB that holds the public IP.

Answer 2

As stated in the comment above you can do the same via Application Gateway in Azure. But if you are going to only use AKS you might want to just use Application Gateway as your ingress controller which is already created with the private cluster.
Please follow this to achieve the same https://microsoft.github.io/AzureTipsAndTricks/blog/tip256.html

Answer 3

Based on your description i understand that you want to have ingress traffic through your NGINX ingress controller which has a Loadbalancer service with static IP. If your deployment is correctly configured the a Loadbalancer service should be assigned to your NGINX ingress controller with a public IP. Since i dont know your namespaces, naming of deployments etc try:
kubectl get services --all-namespaces | grep -i loadbalancer
You should be able to find that an nginx loadbalancer service has a public IP. Now since NGINX is your ingress controller this means that you have a Layer 7 loadbalancer as ingress so you need to create an ingress route to your application running in AKS. This is documented here from Azure NGINX ingress but also here Ingress K8s