No this is not possible to change the fqdn as you could have multiple services with the same name and Rancher wouldn’t know which service to route to.
This is the reason that the fqdn contains stackName and environmentName.
Our preference would be to have something like this:
fqdn=.
I actually tried to fork the external-dns repo for this and change the code creating the fqdn - which was quite easy. I have then build But for some reason the stack is not starting up properly when the containers are deployed. Might be something “fgo” specific I am not doing before building my container.
The ideal solution would be to have various supported options available in the official image.
As far as I can see, having stackname.zoneName should be ok - as all stacks have the be uniquely named.
It would also be great if this kind of functionality was included in the Rancher load balancers, so that you get service dynamic discovery with configurable fdqdn names for the load balancer to handle.