refactor(reverse-proxy): use route registry

modules/reverse-proxy.nix

@@ -1,10 +1,34 @@
-{ config, lib, my, ... }:
+{
+  config,
+  lib,
+  my,
+  registry ? config.registry,
+  ...
+}:
 let
   cfg = config.modules.reverse-proxy;
   inherit (my) reverseProxyRoutes;
 
-  enabledRoutes = lib.filterAttrs (_: route: route.enable) cfg.routes;
-  routesByHost = lib.groupBy (route: route.host) (lib.attrValues enabledRoutes);
+  routeWithBackend = hostName: routeName: route:
+    let
+      facts = my.registry.at registry hostName routeName;
+    in
+    if route.backend != null then
+      route
+    else if facts ? address && route.port != null then
+      route // { backend = "${route.scheme}://${facts.address}:${toString route.port}"; }
+    else
+      route;
+
+  allRoutes = lib.concatLists (
+    lib.mapAttrsToList (
+      hostName: routes:
+      lib.mapAttrsToList (routeName: route: routeWithBackend hostName routeName route) routes
+    ) cfg.routes
+  );
+
+  enabledRoutes = builtins.filter (route: route.enable) allRoutes;
+  routesByHost = lib.groupBy (route: route.host) enabledRoutes;
 
   rootRoutesByHost = lib.mapAttrs (
     host: routes:
@@ -47,9 +71,9 @@ in
     enable = lib.mkEnableOption "the Nginx reverse proxy route realizer";
 
     routes = lib.mkOption {
-      type = lib.types.attrsOf reverseProxyRoutes.routeType;
+      type = lib.types.attrsOf (lib.types.attrsOf reverseProxyRoutes.routeType);
       default = { };
-      description = "Reverse-proxy route declarations keyed by stable route name.";
+      description = "Reverse-proxy route declarations keyed by source host and stable route name.";
     };
   };
 
@@ -66,7 +90,7 @@ in
       ++ map (route: {
         assertion = !hasUnresolvedBackend route;
         message = "modules.reverse-proxy.routes for ${route.host}${route.path} must resolve to a backend URL before actualization.";
-      }) (builtins.filter hasUnresolvedBackend (lib.attrValues enabledRoutes));
+      }) (builtins.filter hasUnresolvedBackend enabledRoutes);
 
     networking.firewall.allowedTCPPorts = [
       80