To help with using
letsencrypt there’s an option in Terraform variables to enable
certmanager in the cluster.
certmanager is installed, you still need to create the cluster issuer.
After it’s the cluster issuer is created, the next steps are to configure the ingress to use these certificates. You can follow the same Microsoft guide for this.
If you plan to use normal certificates, it’s best to follow Microsoft’s tips on how to set up Secrets Store CSI Driver to Enable NGINX Ingress Controller with TLS.