Elixir Phoenix not loading env variable at runtime

Question

I am trying to load an API key as a system env from my mac when starting up the phoenix server. What am I getting wrong? these are my steps:

1. On my mac terminal:

   export API_NOTIFICATION_KEY=1234
   

2. in my config.exs

   config :app, App.Notifications,
   notification_api_key: {:system, "API_NOTIFICATION_KEY"}
   

3. in my module where I use it

   @api_notification_key Application.get_env(:app, App.Notifications)[:notification_api_key]
   

4. start my phoenix server

   mix phx.server
   

And then When I try to make the API call it is showing as nil. Is there a step I am missing to get it properly loaded ?

Answer 1

Attributes are evaluated during compilation, so:

@api_notification_key Application.get_env(:app, App.Notifications)[:notification_api_key]

will have its value set at compile time. I assume that's not what you want, so you'll be better off using a function:

defp api_notification_key() do
  case Application.get_env(:test, App.Notifications)[:notification_api_key] do
    {:system, var_name} -> System.get_env(var_name)
    value -> value
  end
end