Add PromEx.

.devcontainer/docker-compose.yml

@@ -7,7 +7,7 @@ services:
       dockerfile: Dockerfile
       args:
         # Elixir Version: 1.9, 1.10, 1.10.4, ...
-        VARIANT: '1.15.4'
+        VARIANT: '1.15.5'
         # Phoenix Version: 1.4.17, 1.5.4, ...
         PHOENIX_VERSION: '1.7.7'
         # Node Version: 12, 14, ...
@@ -22,7 +22,7 @@ services:
     command: sleep infinity
 
   db:
-    image: postgres:15.3-bullseye
+    image: postgres:15.4-bullseye
     restart: unless-stopped
     volumes:
       - postgres-data:/var/lib/postgresql/data

config/config.exs

@@ -48,6 +48,31 @@ if Mix.env() == :dev do
     ]
 end
 
+# Configures prom_ex
+config :zero_phoenix, ZeroPhoenix.PromEx,
+  disabled: false,
+  manual_metrics_start_delay: :no_delay,
+  drop_metrics_groups: [],
+  grafana: [
+    host: System.get_env("GRAFANA_HOST", "http://localhost:3000"),
+    username: System.get_env("GF_SECURITY_ADMIN_USER", "admin"),
+    password: System.get_env("GF_SECURITY_ADMIN_PASSWORD", "admin"),
+    folder_name: "zero-to-graphql-using-elixir",
+    upload_dashboards_on_start: true,
+    annotate_app_lifecycle: true
+  ],
+  metrics_server: [
+    protocol: :http,
+    path: "/metrics",
+    port: 4021,
+    pool_size: 5,
+    cowboy_opts: [],
+    auth_strategy: :none
+  ]
+
+# config :zero_phoenix, ZeroPhoenix.PromEx,
+#   grafana_datasource_id: System.get_env("GRAFANA_DATASOURCE_ID", "Local Prometheus")
+
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{config_env()}.exs"

config/prod.exs

@@ -12,3 +12,25 @@ config :logger, level: :info
 
 # Runtime production configuration, including reading
 # of environment variables, is done on config/runtime.exs.
+
+# Configures prom_ex
+config :zero_phoenix, ZeroPhoenix.PromEx,
+  disabled: false,
+  manual_metrics_start_delay: :no_delay,
+  drop_metrics_groups: [],
+  grafana: [
+    host: System.get_env("GRAFANA_HOST", raise("GRAFANA_HOST is required")),
+    auth_token: System.get_env("GRAFANA_TOKEN", raise("GRAFANA_TOKEN is required")),
+    folder_name: "zero-to-graphql-using-elixir",
+    upload_dashboards_on_start: true,
+    annotate_app_lifecycle: true
+  ],
+  metrics_server: [
+    protocol: :http,
+    path: "/metrics",
+    port: 4021,
+    pool_size: 5,
+    cowboy_opts: []
+    auth_strategy: :bearer,
+    auth_token: "<YOUR_AUTH_TOKEN_HERE>",
+  ]

lib/zero_phoenix/application.ex

@@ -7,16 +7,18 @@ defmodule ZeroPhoenix.Application do
 
   def start(_type, _args) do
     children = [
-      # Start the Ecto repository
-      ZeroPhoenix.Repo,
+      # Start the PromEx
+      ZeroPhoenix.PromEx,
       # Start the Telemetry supervisor
       ZeroPhoenixWeb.Telemetry,
+      # Start the Ecto repository
+      ZeroPhoenix.Repo,
       # Start the PubSub system
       {Phoenix.PubSub, name: ZeroPhoenix.PubSub},
-      # Start the endpoint when the application starts
+      # Start Finch
+      {Finch, name: ZeroPhoenix.Finch},
+      # Start the Endpoint (http/https)
       ZeroPhoenixWeb.Endpoint
-      # Start your own worker by calling: ZeroPhoenix.Worker.start_link(arg1, arg2, arg3)
-      # worker(ZeroPhoenix.Worker, [arg1, arg2, arg3]),
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/zero_phoenix/prom_ex.ex

@@ -0,0 +1,103 @@
+defmodule ZeroPhoenix.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 :zero_phoenix, ZeroPhoenix.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 = [
+         ZeroPhoenix.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 ZeroPhoenixWeb.Endpoint do
+       use Phoenix.Endpoint, otp_app: :zero_phoenix
+
+       ...
+
+       plug PromEx.Plug, prom_ex_module: ZeroPhoenix.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: :zero_phoenix
+
+  alias PromEx.Plugins
+
+  @impl true
+  def plugins do
+    [
+      # PromEx built in plugins
+      Plugins.Application,
+      Plugins.Beam,
+      {Plugins.Phoenix, router: ZeroPhoenixWeb.Router, endpoint: ZeroPhoenixWeb.Endpoint},
+      Plugins.Ecto,
+      # Plugins.Oban,
+      Plugins.PhoenixLiveView,
+      Plugins.Absinthe
+      # Plugins.Broadway,
+
+      # Add your own PromEx metrics plugins
+      # ZeroPhoenix.Users.PromExPlugin
+    ]
+  end
+
+  @impl true
+  def dashboard_assigns do
+    [
+      datasource_id: "Local Prometheus",
+      # datasource_id: Application.get_env(:zero_phoenix, :grafana_datasource_id),
+      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"}
+      # {:zero_phoenix, "/grafana_dashboards/user_metrics.json"}
+    ]
+  end
+end

lib/zero_phoenix_web/endpoint.ex

@@ -35,6 +35,7 @@ defmodule ZeroPhoenixWeb.Endpoint do
     cookie_key: "request_logger"
 
   plug Plug.RequestId
+  plug PromEx.Plug, prom_ex_module: ZeroPhoenix.PromEx
   plug Plug.Telemetry, event_prefix: [:phoenix, :endpoint]
 
   plug Plug.Parsers,