fix: track global payload size metric (#1496)

Author: edgurgel

lib/realtime/monitoring/prom_ex/plugins/tenant.ex

@@ -35,11 +35,21 @@ defmodule Realtime.PromEx.Plugins.Tenant do
           [:realtime, :tenants, :payload, :size],
           event_name: [:realtime, :tenants, :payload, :size],
           measurement: :size,
-          description: "Payload size",
+          description: "Tenant payload size",
           tags: [:tenant],
           unit: :byte,
           reporter_options: [
-            buckets: [100, 250, 500, 1000, 2000, 3000, 5000]
+            buckets: [100, 250, 500, 1000, 2000, 3000, 5000, 10_000, 25_000]
+          ]
+        ),
+        distribution(
+          [:realtime, :payload, :size],
+          event_name: [:realtime, :tenants, :payload, :size],
+          measurement: :size,
+          description: "Payload size",
+          unit: :byte,
+          reporter_options: [
+            buckets: [100, 250, 500, 1000, 2000, 3000, 5000, 10_000, 25_000]
           ]
         )
       ]

mix.exs

@@ -4,7 +4,7 @@ defmodule Realtime.MixProject do
   def project do
     [
       app: :realtime,
-      version: "2.42.1",
+      version: "2.42.2",
       elixir: "~> 1.17.3",
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,

test/realtime/monitoring/prom_ex/plugins/tenant_test.exs

@@ -227,7 +227,7 @@ defmodule Realtime.PromEx.Plugins.TenantTest do
       assert metric_value(bucket_pattern) > 0
     end
 
-    test "metric payload size", context do
+    test "tenant metric payload size", context do
       external_id = context.tenant.external_id
 
       pattern =
@@ -246,6 +246,24 @@ defmodule Realtime.PromEx.Plugins.TenantTest do
 
       assert metric_value(bucket_pattern) > 0
     end
+
+    test "global metric payload size", context do
+      external_id = context.tenant.external_id
+
+      pattern = ~r/realtime_payload_size_count\s(?<number>\d+)/
+
+      metric_value = metric_value(pattern)
+
+      message = %{topic: "a topic", event: "an event", payload: ["a", %{"b" => "c"}, 1, 23]}
+      RealtimeWeb.TenantBroadcaster.pubsub_broadcast(external_id, "a topic", message, Phoenix.PubSub)
+
+      Process.sleep(200)
+      assert metric_value(pattern) == metric_value + 1
+
+      bucket_pattern = ~r/realtime_payload_size_bucket{le="100"}\s(?<number>\d+)/
+
+      assert metric_value(bucket_pattern) > 0
+    end
   end
 
   defp metric_value(pattern) do