⭐ prometheus plug exporter 추가

- localhost:4000/metrics 주소로 prometheus가 읽을 수 있게 metrics를
  익스포트한다.

lib/ppg/application.ex

@@ -6,6 +6,8 @@ defmodule Ppg.Application do
   use Application
 
   def start(_type, _args) do
+    Ppg.Metrics.Setup.setup()
+
     # List all child processes to be supervised
     children = [
       # Start the endpoint when the application starts

lib/ppg/metrics/setup.ex

@@ -0,0 +1,5 @@
+defmodule Ppg.Metrics.Setup do
+  def setup do
+    PpgWeb.MetricsExporter.setup()
+  end
+end

lib/ppg_web/endpoint.ex

@@ -43,5 +43,8 @@ defmodule PpgWeb.Endpoint do
   plug Plug.MethodOverride
   plug Plug.Head
   plug Plug.Session, @session_options
+
+  plug PpgWeb.MetricsExporter
+
   plug PpgWeb.Router
 end

lib/ppg_web/metrics_exporter.ex

@@ -0,0 +1,3 @@
+defmodule PpgWeb.MetricsExporter do
+  use Prometheus.PlugExporter
+end

mix.exs

@@ -38,7 +38,9 @@ defmodule Ppg.MixProject do
       {:phoenix_live_reload, "~> 1.2", only: :dev},
       {:gettext, "~> 0.11"},
       {:jason, "~> 1.0"},
-      {:plug_cowboy, "~> 2.0"}
+      {:plug_cowboy, "~> 2.0"},
+      {:prometheus_ex, "~> 3.0"},
+      {:prometheus_plugs, "~> 1.1"}
     ]
   end
 end

mix.lock

@@ -1,4 +1,5 @@
 %{
+  "accept": {:hex, :accept, "0.3.5", "b33b127abca7cc948bbe6caa4c263369abf1347cfa9d8e699c6d214660f10cd1", [:rebar3], [], "hexpm"},
   "cowboy": {:hex, :cowboy, "2.7.0", "91ed100138a764355f43316b1d23d7ff6bdb0de4ea618cb5d8677c93a7a2f115", [:rebar3], [{:cowlib, "~> 2.8.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.7.1", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm"},
   "cowlib": {:hex, :cowlib, "2.8.0", "fd0ff1787db84ac415b8211573e9a30a3ebe71b5cbff7f720089972b2319c8a4", [:rebar3], [], "hexpm"},
   "file_system": {:hex, :file_system, "0.2.7", "e6f7f155970975789f26e77b8b8d8ab084c59844d8ecfaf58cbda31c494d14aa", [:mix], [], "hexpm"},
@@ -12,6 +13,9 @@
   "plug": {:hex, :plug, "1.8.3", "12d5f9796dc72e8ac9614e94bda5e51c4c028d0d428e9297650d09e15a684478", [:mix], [{:mime, "~> 1.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm"},
   "plug_cowboy": {:hex, :plug_cowboy, "2.1.2", "8b0addb5908c5238fac38e442e81b6fcd32788eaa03246b4d55d147c47c5805e", [:mix], [{:cowboy, "~> 2.5", [hex: :cowboy, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
   "plug_crypto": {:hex, :plug_crypto, "1.0.0", "18e49317d3fa343f24620ed22795ec29d4a5e602d52d1513ccea0b07d8ea7d4d", [:mix], [], "hexpm"},
+  "prometheus": {:hex, :prometheus, "4.5.0", "8f4a2246fe0beb50af0f77c5e0a5bb78fe575c34a9655d7f8bc743aad1c6bf76", [:mix, :rebar3], [], "hexpm"},
+  "prometheus_ex": {:hex, :prometheus_ex, "3.0.5", "fa58cfd983487fc5ead331e9a3e0aa622c67232b3ec71710ced122c4c453a02f", [:mix], [{:prometheus, "~> 4.0", [hex: :prometheus, repo: "hexpm", optional: false]}], "hexpm"},
+  "prometheus_plugs": {:hex, :prometheus_plugs, "1.1.5", "25933d48f8af3a5941dd7b621c889749894d8a1082a6ff7c67cc99dec26377c5", [:mix], [{:accept, "~> 0.1", [hex: :accept, repo: "hexpm", optional: false]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: false]}, {:prometheus_ex, "~> 1.1 or ~> 2.0 or ~> 3.0", [hex: :prometheus_ex, repo: "hexpm", optional: false]}, {:prometheus_process_collector, "~> 1.1", [hex: :prometheus_process_collector, repo: "hexpm", optional: true]}], "hexpm"},
   "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm"},
   "telemetry": {:hex, :telemetry, "0.4.1", "ae2718484892448a24470e6aa341bc847c3277bfb8d4e9289f7474d752c09c7f", [:rebar3], [], "hexpm"},
 }