Add more certificate information into prometheus metrics about cert-manager

[wallrj]

Thanks @gbassinello

I want to build a Grafana dashboard using the Prometheus data source to list all ingresses that aren't managed by cert-manager.

Given that problem, I prefer your alternative suggestion, but I'm happy to change my mind if that turns out not to be viable.

List all ingresses using the kube_state_metrics kube_ingress_annotations metric that don't have a cert-manager annotation.

I tried it out locally

EDITOR=vi kubectl edit -n prometheus deployments.apps default-kube-state-metrics

    spec:
      containers:
      - args:
        - --metric-annotations-allowlist=ingresses=[cert-manager.io/issuer,cert-manager.io/cluster-issuer],secrets=[cert-manager.io/certificate-name]

kubectl get --raw /api/v1/namespaces/prometheus/services/default-kube-state-metrics:8080/proxy/metrics | grep annotation_cert_manager_io

kube_ingress_annotations{namespace="default",ingress="example-1",annotation_cert_manager_io_cluster_issuer="issuer-1"} 1
kube_secret_annotations{namespace="default",secret="example-1-tls",annotation_cert_manager_io_certificate_name="example-1-tls"} 1
kube_secret_annotations{namespace="samplewebhook",secret="samplewebhook-example-webhook-webhook-tls",annotation_cert_manager_io_certificate_name="samplewebhook-example-webhook-webhook-tls"} 1
kube_secret_annotations{namespace="samplewebhook",secret="samplewebhook-example-webhook-ca",annotation_cert_manager_io_certificate_name="samplewebhook-example-webhook-ca"} 1

It should be possible to construct the report from those metrics, right?