Redifining module problem because of Code.eval_file in config.exs

defmodule KayaanPrints.EnvLoader do
  def load_env(path \\ ".env") do
    if File.exists?(path) do
      File.stream!(path)
      |> Stream.map(&String.trim/1)
      |> Enum.each(fn line ->
        [key, value] = String.split(line, "=")
        System.put_env(key, value)
      end)
    end
  end
end

So, I’m using the above module to load env variables into System. And in my config file, I have added the below code:

if config_env() in [:dev, :test] do
  Code.eval_file("lib/kayaan_prints/env_loader.ex")
  KayaanPrints.EnvLoader.load_env()
end

It doesn’t throw any error but it shows this as a problem:
redefining module KayaanPrints.EnvLoader (current version defined in memory)

I think it is due to Code.eval_file which loads and evaluates the file everytime it recompiles. Importing module doesn’t work as well. How do i resolve this? if I don’t want to write the whole module code in config.exs file, is there any way i can somehow import it into config?

I respect doing things manually but there’s already an established way to do what you want - dotenvy. If you’re not working on a personal project I encourage you to give the library a try.

Edit: If you still what to go with a homegrown solution, check the built-in Config.Provider.

1 Like

Thanks a lot sir. But the dotenvy only works during runtime, what if i wanted to load environment variables during compile time without manual code. Are there any libraries available for the same?

Something like this may suppress the warning:

if not function_exported?(KayaanPrints.EnvLoader, :__info__, 1) do
  Code.eval_file("lib/kayaan_prints/env_loader.ex")
end

KayaanPrints.EnvLoader.load_env()
1 Like

Instead of Code.eval_file/1 one should use compile_path: config in your Mix.Project file. More precisely, elixirc_paths: is your friend.

That said, in mix.exs you are to have

  …
  def project do
    [
      …
      elixirc_paths: elixirc_paths(Mix.env()),
      …
    ]

  defp elixirc_paths(:test), do: ["lib", "extras"]
  defp elixirc_paths(:dev), do: ["lib", "extras"]
  defp elixirc_paths(_), do: ["lib"]

Then move your file from the main tree ("lib" dir) to "extras" on the same level as "lib".
And, finally, use that:

if Code.ensure_loaded?(KayaanPrints.EnvLoader),
  do: KayaanPrints.EnvLoader.load_env()
3 Likes

I tried this but it’s still throwing the same warning.

This cannot be the case.

Either you forgot to remove KayaanPrints from lib, or you did not recompile the project fresh. Try mix do clean, compile.