Where to put the service / initialization code in the Elixir / Mix / Phoenix app?

Question

I have an Elixir / Mix application (also Phoenix, but there are many non-Phoenix too), and I’m wondering what is the best way to use the “launch” code, for example, to dynamically add children to executives shooting “I'm alive!” pings or other things that you want to perform immediately after launch.

One obvious place is the file Application, but the expected return is the return from Supervisor.start_link(children, opts). So, for example, in a Phoenix application, I could do this:

defmodule MyApp do
  use Application

  def start(_type, _args) do
    import Supervisor.Spec

    children = [
      supervisor(MyApp.Repo, []),
      supervisor(MyApp.Endpoint, []),
      supervisor(MyApp.DynamicSupervisorThingy, [])
    ]
    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
    start_val = Supervisor.start_link(children, opts)



    # --- Put things right here that I want to start ----
    MyApp.DynamicSupervisorThingy.add_children_dynamically()
    MyApp.SomeModule.do_some_thingy()
    MyApp.OtherModule.send_some_pings()
    if MIX_ENV == :prod do
      MyApp.YetAnother.prod_stuff_i_dont_want_in_dev()
    end


    start_val
  end
end

This seems wrong, but I cannot figure out where I should put this code.

Answer 1

. Phoenix - OTP, , . Application.start {:ok, pid}, .

, - , " " , , - - - , - init, .

Application.start , : -)