defmodule MyApp_808732.AuthController do
  use MyApp_808732.Web, :controller

  def index(conn, _params) do
    redirect conn, external: "https://www.fitbit.com/oauth2/authorize"
  end
end

defmodule MyApp_808732.AuthController do
  use MyApp_808732.Web, :controller

  def index(conn, _params) do
    redirect conn, external: Fitbit.authorize_url!(scope: "settings sleep")
  end
end

Use url generated by Fitbit strategy module
Use url generated by Fitbit strategy module

wsmoak/my_app_808732