{ ... }:
{

  # See https://nixos.wiki/wiki/Gitlab_runner
  # boot.kernel.sysctl."net.ipv4.ip_forward" = true; # 1
  # virtualisation.docker.enable = true;
  # services.gitlab-runner = {
  #   enable = true;
  #   services= {
  #     # runner for building in docker via host's nix-daemon
  #     # nix store will be readable in runner, might be insecure
  #     nix = with lib;{
  #       # File should contain at least these two variables:
  #       # `CI_SERVER_URL`
  #       # `REGISTRATION_TOKEN`
  #       registrationConfigFile = toString ./path/to/ci-env; # 2
  #       dockerImage = "alpine";
  #       dockerVolumes = [
  #         "/nix/store:/nix/store:ro"
  #         "/nix/var/nix/db:/nix/var/nix/db:ro"
  #         "/nix/var/nix/daemon-socket:/nix/var/nix/daemon-socket:ro"
  #       ];
  #       dockerDisableCache = true;
  #       preBuildScript = pkgs.writeScript "setup-container" ''
  #         mkdir -p -m 0755 /nix/var/log/nix/drvs
  #         mkdir -p -m 0755 /nix/var/nix/gcroots
  #         mkdir -p -m 0755 /nix/var/nix/profiles
  #         mkdir -p -m 0755 /nix/var/nix/temproots
  #         mkdir -p -m 0755 /nix/var/nix/userpool
  #         mkdir -p -m 1777 /nix/var/nix/gcroots/per-user
  #         mkdir -p -m 1777 /nix/var/nix/profiles/per-user
  #         mkdir -p -m 0755 /nix/var/nix/profiles/per-user/root
  #         mkdir -p -m 0700 "$HOME/.nix-defexpr"
  #         . ${pkgs.nix}/etc/profile.d/nix.sh
  #         ${pkgs.nix}/bin/nix-channel --add https://nixos.org/channels/nixos-20.09 nixpkgs # 3
  #         ${pkgs.nix}/bin/nix-channel --update nixpkgs
  #         ${pkgs.nix}/bin/nix-env -i ${concatStringsSep " " (with pkgs; [ nix cacert git openssh ])}
  #       '';
  #       environmentVariables = {
  #         ENV = "/etc/profile";
  #         USER = "root";
  #         NIX_REMOTE = "daemon";
  #         PATH = "/nix/var/nix/profiles/default/bin:/nix/var/nix/profiles/default/sbin:/bin:/sbin:/usr/bin:/usr/sbin";
  #         NIX_SSL_CERT_FILE = "/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt";
  #       };
  #       tagList = [ "nix" ];
  #     };
  #   };
  # };

}