Create a module for a package with many /etc files

So I want to package OpenNebula.
After compilation, and installation process, I got a result folder containing the binary and many many config files in result/etc.

How can I translate this inside a NixOS module so that the config files are all symlinked to /etc ?
Do I have to do it “by hand” using environment.etc.<name> ?

(Source of the experimentation bench for this: GitHub - litchipi/nixos-service-builder at opennebula)