nixos-servers/modules/custom/k3s/default.nix

{ pkgs, lib, config, kubenix, ... }:
let cfg = config.custom.k3s;
in {
  options = {
    custom = {
      k3s.enable = lib.mkOption {
        default = false;
        type = lib.types.bool;
        description = ''
          Whether to start k3s with custom configuration.
        '';
      };
    };
  };

  config = lib.mkIf cfg.enable {
    environment.systemPackages = [ pkgs.k3s ];
    services.k3s.enable = true;
    services.k3s.role = "server";
    services.k3s.extraFlags = "--tls-san ${config.networking.fqdn} --data-dir ${config.custom.dataDisk.mountPoint}/k3s";

    system.activationScripts.k3s-bootstrap.text =
      let
        k3sBootstrapFile = (kubenix.evalModules.x86_64-linux {
          module = import ./bootstrap.nix;
        }).config.kubernetes.result;
      in
      ''
        ln -sf ${k3sBootstrapFile} ${config.custom.dataDisk.mountPoint}/k3s/server/manifests/k3s-bootstrap.json
      '';
  };
}