PlugSocket

Online Documentation.

Enables a convenient way of specifying sockets within your Plug.Router.

PlugSocket is not a Plug itself. Instead, it provides a convenient DSL for specifying any sockets as part of your Plug.Router that can later be added to the Plug.Cowboy adapter.

Because it is not tied to Plug or Plug.Router directly, it can also be used independently of Plug, if one wants to just use Cowboy directly.

Usage

Add the PlugSocket to your router. E.g.,

defmodule MyApp.Router do
  use Plug.Router

  socket "/my-socket", MyApp.MySocket

  plug :match
  plug :dispatch

  get "/" do
    send_resp(conn, 200, "hello world")
  end
end

Each module you pass to socket/3 must implement the :cowboy_websocket_handler behavior. Note that because socket/3 is not a Plug, it is not part of any plug pipeline you create in your router.

Next, you need to ensure our websockets are added to the Cowboy dispatch:

def start(_type, _args) do
  children = [
    {Plug.Cowboy, scheme: :http, plug: MyApp.Router, options: [
      dispatch: PlugSocket.plug_cowboy_dispatch(MyApp.Router)
    ]}
  ]

  opts = [strategy: :one_for_one, name: MyApp.Supervisor]
  Supervisor.start_link(children, opts)
end

This registers your sockets with the Cowboy dispatcher. You can now start the application and navigate to your socket path in your client and see that it is now routing!