Like the gitbook provide a custom domain I've to design a service and user can register their custom domain. For example, I've a service hosting.example.com and user can register any domain based on this service. In the case I wish user JUST edit the CNAME, for example sub1.example.net CNAME TO hosting.example.com.
My service already process the virtual host and can provide service normally on HTTP. Now I have to provide HTTPS with lets encrypt. I've survey the acem.sh but HAVE TO extra CNAME _acme-challenge.sub1.example.net. I want to reduct this step and keep user just edit DNS one and only one CNAME record.
Since my service is based on the K8S environment and HTTP-01 challenge is not suitable on this case.
[UPDATE] Since I've using the wildcard CA, the DNS 01 seems the only possible method.