Rancher 2.5.7 GUI letsencrypt

I’ve setup a new 3 node rancher installation and would like to replace the self-signed certificate with a LetsEncrypt cert.

The cluster was setup using RancherD

I assume I need to update the RancherD configuration to use LetsEncrypt but the only documentation for updating certs says to “use your own .pem files”. I don’t see any reference to SSL in the Common Options sections.

This cluster will only be used to manage other k8s clusters no workloads will be run on it

Is there any how-to on using switching to LetsEncrypt for the UI?