Add observer, prometheus and grafana

src/eventhub_app.erl

@@ -14,6 +14,9 @@ start(_StartType, _StartArgs) ->
       ok = infra_mnesia:wait_for_tables(),
       start_http(),
       start_admin_http(),
+      % Запускаем сборщик метрик Prometheus
+      application:ensure_all_started(prometheus),
+      application:ensure_all_started(prometheus_cowboy),
       {ok, Pid};
     Error ->
       Error
@@ -27,6 +30,7 @@ start_http() ->
 
   Dispatch = cowboy_router:compile([
     {'_', [
+      {"/metrics/[:registry]", prometheus_cowboy2_handler, []},
       {"/health", handler_health, []},
       {"/v1/register", handler_register, []},
       {"/v1/login", handler_login, []},