Certificate without Issuer - only monitoring of existing certificates

[majooneez]

Hello,

I had to install cert-manager on my cluster because it is required to install Jaeger. If I have this tool I thought I can use it somehow, I order certificates manually and renew them manually and I dont want to change that. The only thing I'd like to use in cert-manager is Prometheus metrics to create some dashboard in Grafana with existing certificates and see when they expire. I thought I can get this working if I just create Certificate object and refer to secret with existing cert, but this is not possible due to:
Error from server (NotAcceptable): error when creating "certmanager-certificate.yml": admission webhook "webhook.cert-manager.io" denied the request: [spec.issuerRef.name: Required value: must be specified, spec: Invalid value: "": at least one of commonName, dnsNames, uris ipAddresses, or emailAddresses must be set]

Is my idea too simple for cert-manager? Can't I just have Certificate object and no Issuer (because I don't need that)? Is there any workaround with creating dummy Issuer or something? Maybe I do not understand something but if one of the feature is to get metrics and notification about expiring certificates, why it has to be connected to Issuer?

Cheers,
majonez