ingress-nginx: nginx_ingress_controller_requests is missing for Ingress that has had no requests

NGINX Ingress controller version: 0.30.0

Kubernetes version (use kubectl version): 1.15

Environment:

• EKS k8s cluster

What happened:

The nginx_ingress_controller_requests metric was missing for Ingresses that have had 0 requests. I queried nginx_ingress_controller_requests == 0 for our prometheus metrics and found no time series.

What you expected to happen:

I expected ingresses that have had no requests sent to them to have a nginx_ingress_controller_requests metric with a count of 0 rather than not being present.

How to reproduce it:

• I deployed a test Ingress object (very basic config) with the host name set
• I waited for the Ingress controller to show the host and address, I’ve seen other bugs raised that state this metric won’t show if the host isn’t set but I don’t think that applies here

$ kubectl --context <CONTEXT> -n <NAMESPACE> get ing test
NAME       HOSTS          ADDRESS                 PORTS     AGE
test       <DOMAIN>  <LB_ADDRESS>      <PORTS>   7h40m

• I looked for the metric in prometheus for this ingress but couldn’t find it nginx_ingress_controller_requests{ingress="test"}
• I also exec’d to a pod on the cluster and hit the NGINX controller’s /metrics endpoint to check if our prometheus stack was filtering out the metric, but it didn’t appear there either

Anything else we need to know:

Please let me know if you need any other info from me, thanks for your time 😃

/kind bug