vm stats are coming through

lib/dotcom/application.ex

@@ -8,8 +8,6 @@ defmodule Dotcom.Application do
 
   use Application
 
-  alias Telemetry.Metrics
-
   # See http://elixir-lang.org/docs/stable/elixir/Application.html
   # for more information on OTP Applications
   def start(_type, _args) do
@@ -29,11 +27,12 @@ defmodule Dotcom.Application do
     children =
       [
         {Application.get_env(:dotcom, :cache, Dotcom.Cache.Multilevel), []},
+        {DotcomWeb.Telemetry, []},
         {Req.Telemetry, []}
       ] ++
         if Application.get_env(:dotcom, :env) != :test do
           [
-            # We can't run telemetry in the test environment because none of the levels are running
+            # We can't run cache telemetry in the test environment because none of the levels are running
             {Dotcom.Cache.Telemetry, []},
             # We don't need to run this cache because we are using the local cache for tests
             {Dotcom.Cache.TripPlanFeedback.Cache, []}

lib/dotcom/telemetry.ex

@@ -0,0 +1,38 @@
+defmodule Dotcom.Telemetry do
+  @moduledoc """
+  """
+
+  use Supervisor
+
+  alias Telemetry.Metrics
+
+  def start_link(arg) do
+    Supervisor.start_link(__MODULE__, arg, name: __MODULE__)
+  end
+
+  def init(_arg) do
+    telemetry_metrics_splunk_config = Application.get_env(:dotcom, :telemetry_metrics_splunk)
+
+    children = [
+      {
+        TelemetryMetricsSplunk,
+        [
+          metrics: metrics(),
+          token: telemetry_metrics_splunk_config[:token],
+          url: telemetry_metrics_splunk_config[:url]
+        ]
+      }
+    ]
+
+    Supervisor.init(children, strategy: :one_for_one)
+  end
+
+  defp metrics do
+    [
+      Metrics.last_value("vm.memory.total", unit: :byte),
+      Metrics.last_value("vm.total_run_queue_lengths.total"),
+      Metrics.last_value("vm.total_run_queue_lengths.cpu"),
+      Metrics.last_value("vm.system_counts.process_count")
+    ]
+  end
+end

lib/dotcom_web/stats.ex

@@ -0,0 +1,14 @@
+defmodule DotcomWeb.Stats do
+  @moduledoc """
+  This Agent attaches to telemetry events emitted by Phoenix and aggregates them.
+  """
+
+  use Agent
+
+  @doc """
+  Starts the Agent and attaches to `[:phoenix, ...]` telemetry events.
+  """
+  def start_link(initial_value \\ %{}) do
+    Agent.start_link(fn -> initial_value end, name: __MODULE__)
+  end
+end

lib/dotcom_web/telemetry.ex

@@ -0,0 +1,40 @@
+defmodule DotcomWeb.Telemetry do
+  @moduledoc """
+  This module is responsible for starting the Telemetry poller and defining the metrics to be collected for Phoenix and the Erlang VM.
+  """
+
+  use Supervisor
+
+  alias Telemetry.Metrics
+
+  def start_link(arg) do
+    Supervisor.start_link(__MODULE__, arg, name: __MODULE__)
+  end
+
+  @impl true
+  def init(_arg) do
+    telemetry_metrics_splunk_config = Application.get_env(:dotcom, :telemetry_metrics_splunk)
+
+    children = [
+      {
+        TelemetryMetricsSplunk,
+        [
+          metrics: metrics(),
+          token: telemetry_metrics_splunk_config[:token],
+          url: telemetry_metrics_splunk_config[:url]
+        ]
+      },
+      {DotcomWeb.Stats, %{}}
+    ]
+
+    Supervisor.init(children, strategy: :one_for_one)
+  end
+
+  def measurements do
+    []
+  end
+
+  def metrics do
+    []
+  end
+end

lib/req/stats.ex

@@ -1,6 +1,6 @@
 defmodule Req.Stats do
   @moduledoc """
-  This Agent attaches to telemetry events emitted by Finch and aggregates them by path and status.
+  This Agent attaches to telemetry events emitted by Finch (used by Req) and aggregates them by host, path, and status.
   """
 
   use Agent
@@ -15,7 +15,7 @@ defmodule Req.Stats do
   end
 
   @doc """
-  Handles telemetry events and aggregates them by path and status.
+  Handles telemetry events and aggregates them by host, path, and status.
   """
   def handle_event(_name, measurement, metadata, _config) do
     host = metadata.request.host