spec.duration and spec.renewBefore fields on a Certificate can be used to specify an X.509 certificate's duration and a 'renewBefore' value. Default value for spec.duration is 90 days. Some issuers might be configured to only issue certificates with a set duration, so the actual duration may be different.Minimum value for spec.duration is 1 hour and minimum value for spec.renewBefore is 5 minutes.It is also required that spec.duration > spec.renewBefore.