I created a test elixir lib that uses a file config/config.exs to store env variables for example :

config.exs :

import Config

url_dev = "DEV"
url_prod = "PROD"

config :test_lib,
  dev: [
    url: url_dev,
  ],
  production: [
    url: url_prod,
  ]

and in the lib/test_lib_elixir_package.exs, I called tha variable :

defmodule TestLibElixirPackage do
  def testFunction do
    dev_url = Application.fetch_env!(:test_lib, :dev)
    dev_url[:url]
  end
end

When I test the lib with IEX i can obtain the result of the function testFunction

image767×105 3.04 KB

But When I installed the LIB in an elixir app and tried to call the function I got this error :

“** (ArgumentError) could not fetch application environment :dev for application :test_lib because the application was not loaded nor configured
(elixir 1.13.1) lib/application.ex:683: Application.fetch_env!/2
(test_lib_elixir_package 0.1.2) lib/test_lib_elixir_package.ex:8: TestLibElixirPackage.testFunction/0”

image1428×163 7.36 KB

Here is my mix.exs from the library (I included the config directory) :

defp package do
    [
      files: ["lib", "config", "mix.exs", "README*"],
      description: "Testing build and publish elixir lib",
      maintainers: ["test"],
      licenses: ["MIT"],
      links: %{}
    ]
  end