prepare router to serve single page web app

lib/myapp_web/controllers/page_controller.ex

@@ -0,0 +1,22 @@
+defmodule MyAppWeb.PageController do
+  use MyAppWeb, :controller
+
+  # serve index.html - cache the file after reading it to minimize IO
+  @spec index(map, map) :: any
+  def index(conn, _params) do
+
+    file = Cachex.get(:myapp, "index.html")
+    |> get_file
+
+    conn
+    |> html(file)
+  end
+
+  defp get_file({:ok, data}), do: data
+  defp get_file({:missing, _}) do
+    file = File.read!("./priv/static/index.html")
+    Cachex.set(:myapp, "index.html", file)
+    file
+  end
+  
+end