Add fancyTypist.dev test Servant site

nixos-apps/fancytypist.com.nix

@@ -1,3 +1,8 @@
+let
+  PROJECT_ROOT = "/workspace/deployed-nixos-server-and-apps/nixos-apps/fancytypist.dev";
+  PORT = "12513";
+  HOST = "localhost";
+in
 {
   services.caddy = {
     enable = true;
@@ -19,9 +24,21 @@
       "fancytypist.dev" = {
         serverAliases = [ "www.fancytypist.dev" ];
         extraConfig = ''
-          respond "Hello, world! fancytypist.dev"
+          reverse_proxy ${HOST}:${PORT}
         '';
       };
     };
   };
+
+  systemd.services = {
+    fancyTypist.dev-site = {
+      enable = true;
+      description = "The Haskell Servant executable server that hosts my FancyTypist.dev site.";
+      path = with pkgs; [ nix git ];
+      script = ''
+        cd ${PROJECT_ROOT}
+        nix run .#fancyTypist.dev-site
+      '';
+    };
+  };
 }