nixcfg/modules/hostFile.nix

{ pkgs, lib, config, nodes, ... }:

with lib;

{
  options.hpc.hostFile = {
    addresses = mkOption {
      description = ''
        IP addresses of this host
      '';
      type = types.listOf types.str;
      default =
        let
          interface = config.networking.interfaces.${config.networking.defaultGateway.interface};
        in
        concatLists [
          (map (e: e.address) interface.ipv4.addresses)
          (map (e: e.address) interface.ipv6.addresses)
        ];
    };

    aliases = mkOption {
      description = ''
        Aliases for this host
      '';
      type = types.listOf types.str;
      default = [ ];
    };

    entries = mkOption {
      description = ''
        Host name entries for this host
      '';
      type = types.listOf types.str;
      readOnly = true;
      default = [ config.networking.fqdn config.networking.hostName ] ++ config.hpc.hostFile.aliases;
    };
  };

  config = {
    networking.hosts = listToAttrs (concatMap
      (node: map
        (address: nameValuePair address node.config.hpc.hostFile.entries)
        node.config.hpc.hostFile.addresses)
      (attrValues nodes));
  };
}