Provide metrics on root URL

lib/kafkaex_lag_exporter_web/views/error_helpers.ex

@@ -0,0 +1,16 @@
+defmodule KafkaexLagExporterWeb.ErrorHelpers do
+  @moduledoc """
+  Conveniences for translating and building error messages.
+  """
+
+  @doc """
+  Translates an error message.
+  """
+  def translate_error({msg, opts}) do
+    # Because the error messages we show in our forms and APIs
+    # are defined inside Ecto, we need to translate them dynamically.
+    Enum.reduce(opts, msg, fn {key, value}, acc ->
+      String.replace(acc, "%{#{key}}", fn _ -> to_string(value) end)
+    end)
+  end
+end

lib/kafkaex_lag_exporter_web/views/error_view.ex

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+defmodule KafkaexLagExporterWeb.ErrorView do
+  use KafkaexLagExporterWeb, :view
+
+  # If you want to customize a particular status code
+  # for a certain format, you may uncomment below.
+  # def render("500.json", _assigns) do
+  #   %{errors: %{detail: "Internal Server Error"}}
+  # end
+
+  # By default, Phoenix returns the status message from
+  # the template name. For example, "404.json" becomes
+  # "Not Found".
+  def template_not_found(template, _assigns) do
+    %{errors: %{detail: Phoenix.Controller.status_message_from_template(template)}}
+  end
+end