Create a MetricsEndpoint

This fixes a bunch of `force_ssl` issues since this one endpoint can be http only, plus its easy not to expose it to the world

Author: joshk

config/config.exs

@@ -48,6 +48,11 @@ config :nerves_hub, NervesHubWeb.Endpoint,
   ],
   pubsub_server: NervesHub.PubSub
 
+##
+# NervesHub Metrics
+#
+config :nerves_hub, NervesHubWeb.MetricsEndpoint, adapter: Bandit.PhoenixAdapter
+
 ##
 # Database and Oban
 #

config/dev.exs

@@ -66,6 +66,11 @@ config :nerves_hub, NervesHubWeb.DeviceEndpoint,
     ]
   ]
 
+##
+# NervesHub Metrics
+#
+config :nerves_hub, NervesHubWeb.MetricsEndpoint, http: [ip: {0, 0, 0, 0}, port: 4002]
+
 ##
 # Database and Oban
 #

config/prod.exs

@@ -8,12 +8,21 @@ config :phoenix, logger: false
 ##
 # NervesHub Web
 #
-config :nerves_hub, NervesHubWeb.Endpoint, server: true
+config :nerves_hub, NervesHubWeb.Endpoint,
+  force_ssl: [rewrite_on: [:x_forwarded_proto]],
+  server: true
 
 ##
 # NervesHub Device
 #
-config :nerves_hub, NervesHubWeb.DeviceEndpoint, server: true
+config :nerves_hub, NervesHubWeb.DeviceEndpoint,
+  force_ssl: [rewrite_on: [:x_forwarded_proto]],
+  server: true
+
+##
+# NervesHub Metrics
+#
+config :nerves_hub, NervesHubWeb.MetricsEndpoint, server: true
 
 ##
 # Database and Oban

config/runtime.exs

@@ -168,6 +168,18 @@ if config_env() == :prod do
       ]
   end
 
+  web_port = System.get_env("HTTP_PORT") || System.get_env("PORT") || "4000"
+
+  metrics_port =
+    case System.get_env("METRICS_PORT") do
+      nil -> String.to_integer(web_port) + 40
+      port -> String.to_integer(port)
+    end
+
+  config :nerves_hub, NervesHubWeb.MetricsEndpoint,
+    http: [port: metrics_port],
+    server: true
+
   config :nerves_hub, NervesHubWeb.DeviceSocket,
     shared_secrets: [
       enabled: System.get_env("DEVICE_SHARED_SECRETS_ENABLED", "false") == "true"

lib/nerves_hub/application.ex

@@ -41,7 +41,10 @@ defmodule NervesHub.Application do
           {Oban, Application.fetch_env!(:nerves_hub, Oban)}
         ] ++
         deployments_supervisor(deploy_env()) ++
-        endpoints(deploy_env())
+        endpoints(deploy_env()) ++
+        [
+          NervesHubWeb.MetricsEndpoint
+        ]
 
     opts = [strategy: :one_for_one, name: NervesHub.Supervisor]
     Supervisor.start_link(children, opts)

lib/nerves_hub_web/device_endpoint.ex

@@ -33,8 +33,6 @@ defmodule NervesHubWeb.DeviceEndpoint do
 
   plug(NervesHubWeb.Plugs.ImAlive)
 
-  plug(PromEx.Plug, prom_ex_module: NervesHub.PromEx)
-
   plug(Sentry.PlugContext)
 
   plug(NervesHubWeb.Plugs.Logger)

lib/nerves_hub_web/endpoint.ex

@@ -10,10 +10,6 @@ defmodule NervesHubWeb.Endpoint do
     signing_salt: "1CPjriVa"
   ]
 
-  plug(PromEx.Plug, prom_ex_module: NervesHub.PromEx)
-
-  plug(Plug.SSL, rewrite_on: [:x_forwarded_proto])
-
   socket("/live", Phoenix.LiveView.Socket, websocket: [connect_info: [session: @session_options]])
 
   socket("/socket", NervesHubWeb.UserSocket,

lib/nerves_hub_web/metrics_endpoint.ex

@@ -0,0 +1,7 @@
+defmodule NervesHubWeb.MetricsEndpoint do
+  use Phoenix.Endpoint, otp_app: :nerves_hub
+
+  plug(PromEx.Plug, prom_ex_module: NervesHub.PromEx)
+
+  plug(NervesHubWeb.Plugs.DeviceEndpointRedirect)
+end