fix: Repair /metrics endpoint (#10813)

* fix: Repair /metrics endpoint

* Return back change in the application.ex

apps/block_scout_web/test/block_scout_web/controllers/metrics_contoller_test.exs

@@ -0,0 +1,11 @@
+defmodule BlockScoutWeb.MetricsControllerTest do
+  use BlockScoutWeb.ConnCase
+
+  describe "/metrics page" do
+    test "renders /metrics page", %{conn: conn} do
+      conn = get(conn, "/metrics")
+
+      assert text_response(conn, 200)
+    end
+  end
+end

apps/indexer/lib/indexer/application.ex

@@ -14,29 +14,8 @@ defmodule Indexer.Application do
   alias Indexer.Memory
   alias Prometheus.Registry
 
-  @default_prometheus_collectors [
-    Indexer.Prometheus.Collector.PendingBlockOperations
-  ]
-
-  case Application.compile_env(:explorer, :chain_type) do
-    :filecoin ->
-      @chain_type_prometheus_collectors [
-        Indexer.Prometheus.Collector.FilecoinPendingAddressOperations
-      ]
-
-    _ ->
-      @chain_type_prometheus_collectors []
-  end
-
-  @prometheus_collectors @default_prometheus_collectors ++
-                           @chain_type_prometheus_collectors
-
   @impl Application
   def start(_type, _args) do
-    for collector <- @prometheus_collectors do
-      Registry.register_collector(collector)
-    end
-
     memory_monitor_options =
       case Application.get_env(:indexer, :memory_limit) do
         nil -> %{}

apps/indexer/lib/indexer/prometheus/collector/filecoin_pending_address_operations_collector.ex

@@ -1,4 +1,5 @@
-defmodule Indexer.Prometheus.Collector.FilecoinPendingAddressOperations do
+if Application.compile_env(:explorer, :chain_type) == :filecoin do
+  defmodule Indexer.Prometheus.Collector.FilecoinPendingAddressOperations do
     @moduledoc """
     Custom collector to count number of records in filecoin_pending_address_operations table.
     """
@@ -26,4 +27,5 @@ defmodule Indexer.Prometheus.Collector.FilecoinPendingAddressOperations do
     defp create_gauge(name, help, data) do
       Model.create_mf(name, help, :gauge, __MODULE__, data)
     end
+  end
 end