"Plugging" into Phoenix Channel

I want to inspect socket’s (or channel’s) messages and act on some of them while letting others be handled normally, kinda what Plugs do with requests.

It seems somewhat tricky, I could probably try a handle_in that modifies the socket and uses push with some guards but it doesn’t feel right.

Am I missing something? How does one go about say rate limiting requests on the login topic in a public channel?

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You could write a single handle_in clause and do your rate limiting there. For example:

def handle_in(event, payload, socket) do
  case RateLimiter.log_channel_event(socket.assigns.user_id, event) do
    :ok -> incoming(event, payload, socket)
    {:error, :limited} -> {:reply, {:error, %{reason: "rate_limited"}}, socket}

defp incoming("new_msg", payload, socket) do

defp incoming("...", payload, socket) do

hm so do general stuff in handle_in and delegate the response giving to another function, that’s a step farther then I thought, makes sense, thank you!