I am trying to figure out if there’s an established best practice for connecting child processes within the same supervisor without using name registration.

I have the following processes

• PortCache
• StateServer
• WebServer - requires a PortCache and StateServer for startup

I am using a rest_for_one supervision strategy and trying to create a supervision tree like this.

Supervision tree1788×900 43.9 KB

I’m curious what the best way is to give WebServer a way to send messages to PortCache and WebServer without using name registration.

Here is what I currently have:

defmodule MyApp.Supervisor do

  def start_link(_init_opt) do
    # Start the supervisor with no children
    with {:ok, sup} <- Supervisor.start_link([], strategy: :rest_for_one) do
      {:ok, port_cache} = Supervisor.start_child(sup, PortCache)
      {:ok, state_server} = Supervisor.start_child(sup, StateServer)

      {:ok, _web_server} = 
        Supervisor.start_child(sup, {
          WebServer, 
          port_cache: port_cache, 
          state_server: state_server
         })

       {:ok, sup}
    end
  end
end

I know generally we pass a list of children to a supervisor, but then we don’t have a way to reference the other process’s pids. Are there drawbacks to this approach or a better way of doing this?