ssl_certificate_info metrics shows fake certificate though the host is served with the correct certificate

[Melvin-Antony]

What happened:

We have observed that the nginx_ingress_controller_ssl_certificate_info metric is reporting the 'Kubernetes Ingress Controller Fake Certificate' for certain ingresses, despite the fact that the correct certificate is being served for the corresponding host by the same controller. This inconsistency complicates the effective use of this metric for alerting purposes. Additionally, we have noted that other controllers within the same deployment are providing accurate data, while the erroneous value appears intermittently in only some controller(s).

What you expected to happen:

All the controllers/pods under the deployment show the correct certificate info in the metrics that they produce.

NGINX Ingress controller version (exec into the pod and run /nginx-ingress-controller --version):

NGINX Ingress controller
Release: v1.11.3
Build: 0106de6
Repository: https://github.com/kubernetes/ingress-nginx
nginx version: nginx/1.25.5

Kubernetes version (use kubectl version):
Server Version: v1.31.4-eks-2d5f260

Environment:
Production

• Cloud provider or hardware configuration: AWS / EKS

How to reproduce this issue:
Not exactly sure how to reproduce this behaviour. Restarting the controllers fix the problem temporarily but the problem creeps up after sometime.

[k8s-ci-robot]

This issue is currently awaiting triage.

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