57e5b75f9c
We previously filtered out the `_module` attribute in a NixOS configuration by filtering it using the option's `apply` function. This meant that every option that had a submodule type needed to have this apply function. Adding this function is easy to forget thus this mechanism is error prone. We now recursively filter out the `_module` attributes at the place we construct the Prometheus configuration file. Since we now do the filtering centrally we don't have to do it per option making it less prone to errors.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.