Hi,

I’m trying to use the Gun library to connect to Polygon’s socket server, wss://socket.polygon.io/stocks.

This is the response I expect:

> websocat wss://socket.polygon.io/stocks
[{"ev":"status","status":"connected","message":"Connected Successfully"}]

I’ve written a basic wrapper on the Gun library’s methods, as follows:

  def connect(ws), do: ws_upgrade(ws)

  defp ws_upgrade(%{ path: path, port: port, host: host } = state) do
    {:ok, _} = :application.ensure_all_started(:gun)

    connect_opts = %{
      connect_timeout: :timer.minutes(1),
      retry: 10,
      retry_timeout: 300
    }

    case open_connection(host, port, connect_opts) do
      {:ok, gun_pid} ->
        stream_ref = :gun.ws_upgrade(gun_pid, path)
        %{state | stream_ref: stream_ref, gun_pid: gun_pid}
      {:error, _ } ->
        state
    end
  end

  defp open_connection(host, port, connect_opts) do
    with {:ok, conn_pid} <- :gun.open(host, port, connect_opts),
         {:ok, _protocol} <- :gun.await_up(conn_pid, :timer.minutes(1)) do
      {:ok, conn_pid}
    else
      {:error, reason} ->
        {:error, reason}
    end
  end

I’ve also added Gun response handlers based on this example.

I’ve tested this with basic examples, like 'echo.websockets.org' on port 80, and it works just fine. However, when I try with 'socket.polygon.io' with the path "/stocks", I get a gun_response message with a 308 permanent redirect code. The new location is given by the headers as https://socket.polygon.io/stocks.

This is a bit confusing to me because WebSockets are only available for HTTP/1.1, or at least that’s what the Gun documentation told me, and this seems to want to redirect me to HTTP/2. Has anyone else had to deal with WebSocket redirects like this before? If so, how did you do it? Thanks!