Failed for volume "volume-serving-cert" : secrets "cm-adapter-serving-certs" not found

[Dolphy Phan]

I understand that the volume "volume-serving-cert" has to be set in order to get these two cert works:

• --tls-cert-file=/var/run/serving-cert/serving.crt
• --tls-private-key-file=/var/run/serving-cert/serving.key

But where are these cert from? Is it for prometheus or api server or just a self cert need to be generate?
Many thanks