caddy support multi domain

modules/monitoring/prometheus.nix

@@ -26,6 +26,14 @@ in
         '';
       };
 
+      subdomain = lib.mkOption {
+        default = "prometheus";
+        type = lib.types.str;
+        description = ''
+          The subdomain where Prometheus is reachable
+        '';
+      };
+
       host = lib.mkOption {
         default = "localhost";
         type = lib.types.str;
@@ -94,9 +102,9 @@ in
 
     (lib.mkIf cfg.proxy.enable {
       services.caddy = with cfg.proxy; {
-        virtualHosts."prometheus.${domain}".extraConfig = ''
+        virtualHosts."${subdomain}.${domain}".extraConfig = ''
           reverse_proxy http://${host}:9090
-          import cloudflare
+          import cloudflare_${domain}
         '';
       };
     })