Generate systemd service-files from nixos nginx configuration

nginx.nix

{ nixpkgs ? import <nixpkgs> { }
, pkgs ? nixpkgs.pkgs
, lib ? pkgs.lib
, nixos ? import <nixpkgs/nixos>
}:
let
  config = (nixos {
    configuration.security.acme.certs."example.com".email = "webmaster@example.com";
    configuration.services.nginx = {
      enable = true;
      recommendedOptimisation = true;
      recommendedProxySettings = true;
      recommendedTlsSettings = true;

      virtualHosts."example.com" = {
        forceSSL = true;
        enableACME = true;
        locations."/".proxyPass = "http://127.0.0.1:8080";
      };
    };
  }).config;

  certs = lib.attrNames config.security.acme.certs;
  
  serviceNames = [
    "acme-fixperms.service"
    "acme-selfsigned-ca.service"
    "nginx.service"
    "nginx-config-reload.service"
  ] ++ (lib.concatMap (cert: [
    "acme-${cert}.service"
    "acme-${cert}.timer"
    "acme-finished-${cert}.target"
    "acme-selfsigned-${cert}.service"
  ]) certs);

  filteredServices = lib.filterAttrs (n: _: lib.elem n serviceNames) config.systemd.units;

  systemdLib = import <nixos/modules/system/boot/systemd-lib.nix> { inherit config lib pkgs; };

  services = systemdLib.generateUnits "nginx" pureServices [] [];

in pkgs.runCommand "nginx-system" { preferLocalBuild = true; } ''
  set -e
  mkdir -p $out
  ln -s ${services} $out/system
'' // { inherit config; }

reload.sh

#! /usr/bin/env bash
set -e
nix build -f nginx.nix
sudo cp -Prv result/system/ /etc/systemd/
sudo systemctl daemon-reload
sudo systemctl reload nginx.service