chronoscope/lib/chronoscope_web/live/index_live.ex

defmodule ChronoscopeWeb.IndexLive do
  use ChronoscopeWeb, :live_view

  alias Chronoscope.NTS

  @topic "nts-servers"

  def mount(_params, _session, socket) do
    ChronoscopeWeb.Endpoint.subscribe(@topic)
    {:ok, assign(socket, %{servers: NTS.list()})}
  end

  def handle_info(%{topic: @topic, payload: servers}, socket) do
    {:noreply, assign(socket, %{servers: servers})}
  end
end