System typles example for Phoenix

endpoint.ex

defmodule MyAppAPI.Endpoint do
  use Phoenix.Endpoint, otp_app: :myapp_api
  
  # ...
  
  @doc """
  Callback invoked for dynamically configuring the endpoint.
  It receives the endpoint configuration and checks if
  configuration should be loaded from the system environment.
  """
  def init(_key, config), 
    do: Confex.fetch_env(config)
end