feat: expose system metrics (#4)

Use prom_ex to expose system metrics to prometheus and create dashboards.

Co-authored-by: Joao P Dubas <joao.dubas@gmail.com>
Reviewed-on: #4

Makefile

@@ -36,6 +36,10 @@ compose_up:  ## start containers for this service
 compose_test:  ## run tests in containers
 	@$(COMPOSE) run -e MIX_ENV=test --entrypoint make app test
 
+.PHONY: compose_ps
+compose_ps:  ## status of containers
+	@$(COMPOSE) ps
+
 .PHONY: help
 help:
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

config/config.exs

@@ -14,6 +14,13 @@ config :wabanex, Wabanex.Repo,
   migration_primary_key: [type: :binary_id],
   migration_foreign_key: [type: :binary_id]
 
+config :wabanex, Wabanex.PromEx,
+  disabled: false,
+  manual_metrics_start_delay: :no_delay,
+  drop_metrics_groups: [],
+  grafana: :disabled,
+  metrics_server: :disabled
+
 # Configures the endpoint
 config :wabanex, WabanexWeb.Endpoint,
   url: [host: "localhost"],

docker-compose.yml

@@ -30,23 +30,9 @@ services:
       - 'app_build:/opt/app/_build'
       - 'app_deps:/opt/app/deps'
     working_dir: /opt/app
-    entrypoint: sleep
-    command: infinity
-  pgcli:
-    image: 'joaodubas/pgcli:latest'
-    hostname: development
-    depends_on:
-      - db
-    environment:
-      PGUSER: *db_user
-      PGPASSWORD: *db_pass
-      PGHOST: *db_host
-      PGDATABASE: wabanex_dev
-    volumes:
-      - './priv/docker/pgcli:/root/.config/pgcli'
     restart: unless-stopped
     entrypoint: sleep
-    command: 3650d
+    command: infinity
 
 volumes:
   db_data: {}

lib/wabanex/application.ex

@@ -7,6 +7,8 @@ defmodule Wabanex.Application do
 
   def start(_type, _args) do
     children = [
+      # Start the PromEx supervisor
+      Wabanex.PromEx,
       # Start the Ecto repository
       Wabanex.Repo,
       # Start the Telemetry supervisor

lib/wabanex/prom_ex.ex

@@ -0,0 +1,102 @@
+defmodule Wabanex.PromEx do
+  @moduledoc """
+  Be sure to add the following to finish setting up PromEx:
+
+  1. Update your configuration (config.exs, dev.exs, prod.exs, releases.exs, etc) to
+     configure the necessary bit of PromEx. Be sure to check out `PromEx.Config` for
+     more details regarding configuring PromEx:
+     ```
+     config :wabanex, Wabanex.PromEx,
+       disabled: false,
+       manual_metrics_start_delay: :no_delay,
+       drop_metrics_groups: [],
+       grafana: :disabled,
+       metrics_server: :disabled
+     ```
+
+  2. Add this module to your application supervision tree. It should be one of the first
+     things that is started so that no Telemetry events are missed. For example, if PromEx
+     is started after your Repo module, you will miss Ecto's init events and the dashboards
+     will be missing some data points:
+     ```
+     def start(_type, _args) do
+       children = [
+         Wabanex.PromEx,
+
+         ...
+       ]
+
+       ...
+     end
+     ```
+
+  3. Update your `endpoint.ex` file to expose your metrics (or configure a standalone
+     server using the `:metrics_server` config options). Be sure to put this plug before
+     your `Plug.Telemetry` entry so that you can avoid having calls to your `/metrics`
+     endpoint create their own metrics and logs which can pollute your logs/metrics given
+     that Prometheus will scrape at a regular interval and that can get noisy:
+     ```
+     defmodule WabanexWeb.Endpoint do
+       use Phoenix.Endpoint, otp_app: :wabanex
+
+       ...
+
+       plug PromEx.Plug, prom_ex_module: Wabanex.PromEx
+
+       ...
+     end
+     ```
+
+  4. Update the list of plugins in the `plugins/0` function return list to reflect your
+     application's dependencies. Also update the list of dashboards that are to be uploaded
+     to Grafana in the `dashboards/0` function.
+  """
+
+  use PromEx, otp_app: :wabanex
+
+  alias PromEx.Plugins
+
+  @impl true
+  def plugins do
+    [
+      # PromEx built in plugins
+      Plugins.Application,
+      Plugins.Beam,
+      # {Plugins.Phoenix, router: WabanexWeb.Router, endpoint: WabanexWeb.Endpoint},
+      Plugins.Ecto,
+      # Plugins.Oban,
+      # Plugins.PhoenixLiveView,
+      Plugins.Absinthe
+      # Plugins.Broadway,
+
+      # Add your own PromEx metrics plugins
+      # Wabanex.Users.PromExPlugin
+    ]
+  end
+
+  @impl true
+  def dashboard_assigns do
+    [
+      datasource_id: "prometheus",
+      default_selected_interval: "30s"
+    ]
+  end
+
+  @impl true
+  def dashboards do
+    [
+      # PromEx built in Grafana dashboards
+      {:prom_ex, "application.json"},
+      {:prom_ex, "beam.json"},
+      # {:prom_ex, "phoenix.json"},
+      {:prom_ex, "ecto.json"},
+      # {:prom_ex, "oban.json"},
+      # {:prom_ex, "phoenix_live_view.json"},
+      {:prom_ex, "absinthe.json"}
+      # {:prom_ex, "broadway.json"},
+
+      # Add your dashboard definitions here with the format: {:otp_app, "path_in_priv"}
+      # {:wabanex, "/grafana_dashboards/user_metrics.json"}
+    ]
+  end
+end

lib/wabanex_web/endpoint.ex

@@ -16,6 +16,8 @@ defmodule WabanexWeb.Endpoint do
 
   socket "/live", Phoenix.LiveView.Socket, websocket: [connect_info: [session: @session_options]]
 
+  plug PromEx.Plug, prom_ex_module: Wabanex.PromEx
+
   # Serve at "/" the static files from "priv/static" directory.
   #
   # You should set gzip to true if you are running phx.digest

lib/wabanex_web/schema/types/custom/date_range.ex

@@ -17,10 +17,11 @@ defmodule WabanexWeb.Schema.Types.Custom.DateRange do
   end
 
   @spec serialize_range(PgRanges.DateRange.t()) :: String.t()
-  @spec serialize_range(list(DateTime.t() | nil)) :: String.t()
+  @spec serialize_range(list(DateTime.t() | nil | atom)) :: String.t()
   defp serialize_range(%PgRanges.DateRange{lower: start_range, upper: end_range}),
     do: serialize_range([start_range, end_range])
 
+  defp serialize_range([start_range, :unbound]), do: serialize_range([start_range, nil])
   defp serialize_range([start_range, nil]), do: "#{Date.to_iso8601(start_range)},"
 
   defp serialize_range([start_range, end_range]),

mix.exs

@@ -45,6 +45,7 @@ defmodule Wabanex.MixProject do
       {:phoenix_live_dashboard, "~> 0.6"},
       {:plug_cowboy, "~> 2.0"},
       {:postgrex, ">= 0.0.0"},
+      {:prom_ex, "~> 1.7"},
       {:telemetry_metrics, "~> 0.6"},
       {:telemetry_poller, "~> 1.0"}
     ]

mix.lock

@@ -39,8 +39,10 @@
   "plug_cowboy": {:hex, :plug_cowboy, "2.5.2", "62894ccd601cf9597e2c23911ff12798a8a18d237e9739f58a6b04e4988899fe", [:mix], [{:cowboy, "~> 2.7", [hex: :cowboy, repo: "hexpm", optional: false]}, {:cowboy_telemetry, "~> 0.3", [hex: :cowboy_telemetry, repo: "hexpm", optional: false]}, {:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "ea6e87f774c8608d60c8d34022a7d073bd7680a0a013f049fc62bf35efea1044"},
   "plug_crypto": {:hex, :plug_crypto, "1.2.2", "05654514ac717ff3a1843204b424477d9e60c143406aa94daf2274fdd280794d", [:mix], [], "hexpm", "87631c7ad914a5a445f0a3809f99b079113ae4ed4b867348dd9eec288cecb6db"},
   "postgrex": {:hex, :postgrex, "0.16.2", "0f83198d0e73a36e8d716b90f45f3bde75b5eebf4ade4f43fa1f88c90a812f74", [:mix], [{:connection, "~> 1.1", [hex: :connection, repo: "hexpm", optional: false]}, {:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}], "hexpm", "a9ea589754d9d4d076121090662b7afe155b374897a6550eb288f11d755acfa0"},
+  "prom_ex": {:hex, :prom_ex, "1.7.1", "39331ee3fe6f9a8587d8208bf9274a253bb80281700e127dd18786cda5e08c37", [:mix], [{:absinthe, ">= 1.6.0", [hex: :absinthe, repo: "hexpm", optional: true]}, {:broadway, ">= 1.0.2", [hex: :broadway, repo: "hexpm", optional: true]}, {:ecto, ">= 3.5.0", [hex: :ecto, repo: "hexpm", optional: true]}, {:finch, "~> 0.10.2", [hex: :finch, repo: "hexpm", optional: false]}, {:jason, "~> 1.2", [hex: :jason, repo: "hexpm", optional: false]}, {:oban, ">= 2.4.0", [hex: :oban, repo: "hexpm", optional: true]}, {:phoenix, ">= 1.5.0", [hex: :phoenix, repo: "hexpm", optional: true]}, {:phoenix_live_view, ">= 0.14.0", [hex: :phoenix_live_view, repo: "hexpm", optional: true]}, {:plug, ">= 1.12.1", [hex: :plug, repo: "hexpm", optional: true]}, {:plug_cowboy, "~> 2.5.1", [hex: :plug_cowboy, repo: "hexpm", optional: false]}, {:telemetry, "~> 1.0.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.6.1", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}, {:telemetry_metrics_prometheus_core, "~> 1.0.2", [hex: :telemetry_metrics_prometheus_core, repo: "hexpm", optional: false]}, {:telemetry_poller, "~> 1.0.0", [hex: :telemetry_poller, repo: "hexpm", optional: false]}], "hexpm", "4c978872b88a929833925a0f4d0561824804c671fdd04581e765509ed0a6ed08"},
   "ranch": {:hex, :ranch, "1.8.0", "8c7a100a139fd57f17327b6413e4167ac559fbc04ca7448e9be9057311597a1d", [:make, :rebar3], [], "hexpm", "49fbcfd3682fab1f5d109351b61257676da1a2fdbe295904176d5e521a2ddfe5"},
-  "telemetry": {:hex, :telemetry, "1.1.0", "a589817034a27eab11144ad24d5c0f9fab1f58173274b1e9bae7074af9cbee51", [:rebar3], [], "hexpm", "b727b2a1f75614774cff2d7565b64d0dfa5bd52ba517f16543e6fc7efcc0df48"},
+  "telemetry": {:hex, :telemetry, "1.0.0", "0f453a102cdf13d506b7c0ab158324c337c41f1cc7548f0bc0e130bbf0ae9452", [:rebar3], [], "hexpm", "73bc09fa59b4a0284efb4624335583c528e07ec9ae76aca96ea0673850aec57a"},
   "telemetry_metrics": {:hex, :telemetry_metrics, "0.6.1", "315d9163a1d4660aedc3fee73f33f1d355dcc76c5c3ab3d59e76e3edf80eef1f", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "7be9e0871c41732c233be71e4be11b96e56177bf15dde64a8ac9ce72ac9834c6"},
+  "telemetry_metrics_prometheus_core": {:hex, :telemetry_metrics_prometheus_core, "1.0.2", "c98b1c580de637bfeac00db41b9fb91fb4c3548ee3d512a8ed7299172312eaf3", [:mix], [{:telemetry, "~> 0.4 or ~> 1.0.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:telemetry_metrics, "~> 0.6", [hex: :telemetry_metrics, repo: "hexpm", optional: false]}], "hexpm", "48351a0d56f80e38c997b44232b1043e0a081670d16766eee920e6254175b730"},
   "telemetry_poller": {:hex, :telemetry_poller, "1.0.0", "db91bb424e07f2bb6e73926fcafbfcbcb295f0193e0a00e825e589a0a47e8453", [:rebar3], [{:telemetry, "~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "b3a24eafd66c3f42da30fc3ca7dda1e9d546c12250a2d60d7b81d264fbec4f6e"},
 }

test/wabanex_web/schema/types/custom/date_range_test.exs

@@ -28,6 +28,7 @@ defmodule WabanexWeb.Schema.Types.Custom.DateRangeTest do
     test "serialize a list of dates as a list of ISO8601 date strings" do
       assert "1978-12-15,1980-02-13" == serialize(:date_range, [~D[1978-12-15], ~D[1980-02-13]])
       assert "1978-12-15," == serialize(:date_range, [~D[1978-12-15], nil])
+      assert "1978-12-15," == serialize(:date_range, [~D[1978-12-15], :unbound])
     end
 
     test "serialize a postgres range as a list of ISO8601 date strings" do
@@ -35,6 +36,7 @@ defmodule WabanexWeb.Schema.Types.Custom.DateRangeTest do
                serialize(:date_range, DateRange.new(~D[1978-12-15], ~D[1980-02-13]))
 
       assert "1978-12-15," == serialize(:date_range, DateRange.new(~D[1978-12-15], nil))
+      assert "1978-12-15," == serialize(:date_range, DateRange.new(~D[1978-12-15], :unbound))
     end
 
     test "can be parsed from a string of ISO8601" do