create nginx magic module

nixos/common/modules/nginx.nix

@@ -0,0 +1,32 @@
+{ lib, hosts, config, ... }:
+with lib;
+let cfg = config.services.v.nginx;
+in  {
+  options.services.v.nginx.generateVirtualHosts =
+    mkEnableOption "generate vhosts";
+
+  config = let
+
+    proxy = url: {
+      enableACME = true;
+      forceSSL = true;
+      locations."/" = {
+        proxyPass = url;
+        proxyWebsockets = true;
+      };
+    };
+
+    hosts' =
+      filter (hasAttr "exposes") (attrValues hosts.${config.networking.domain});
+    exposes = { ip, exposes, ... }:
+      map ({ domain, port ? 80}: { inherit ip domain port; }) (attrValues exposes);
+    mkVhost = { ip, domain, port}: {
+      "${domain}" = proxy "http://${ip}:${toString port}";
+    };
+    vhosts = foldr (el: acc: acc // mkVhost el) { } (concatMap exposes hosts');
+  in mkIf cfg.generateVirtualHosts {
+
+    services.nginx.virtualHosts = vhosts;
+
+  };
+}