Configex

Configex helps you to deal with Elixir configuration.

Here are the reasons why I have created this library:

Elixir is a compiled language and getting environment variables on compilation time is wrong in most of times.

On compiled language projects there's usually a CI machine(s) that compiles the code and package it. The compiled code package is usually deployed to another machine(s) to run. Very frequently CI and production machines are even on different networks. Ideally CI machines should not know ENV vars like production secrets, etc.

In addition to that if an ENV var has to change, let's say that you have a new secret due to a new service provision then you cannot just restart the app, but you'll have to run CI again to re-compile and re-deploy the same code base, but with the new ENV var. This is not desirable at all in terms of maintainability of the app you are building.

How to use Configex

The easiest way to use Configex is by calling get_config!/3:

defmodule MyModule do
  use Configex

  def my_config(), do: get_config!(:my_app, :my_config)
end

Cool, so far get_config!/3 will do the same work as Application.get_env/3.

Now let's see how Configex can benefit us.

The benefits of using Configex:

1. 💥 It raises an error if a configuration is missing and if no default is provided.

2. 💥 It raises an error if an ENV var is missing and if no default is provided.

3. 💥 It raises an error if an ENV var is used on compilation time.

4. ⚙️ You can configure ENV vars like config :my_app, my_config: {:system, "MY_ENV"}

5. ⚙️ You can configure ENV vars with a default value like config :my_app, my_config: {:system, "MY_ENV", "<some default>"}

6. ⚙️ You can configure ENV vars recursively like config :my_app, my_config: [port: {:system, "MY_ENV"}]

Configuration Example:

use Mix.Config

config :my_app,
  hardcoded: "Some hardcoded value",
  env: {:system, "MY_ENV", "some system default"}

Usage Example:

  defmodule MyApp.MyModule do
    use Configex

    @hardcoded_conf get_config!(:my_app, :hardcoded)

    def hardcoded_conf(), do: @hardcoded_conf
    def env_conf(), do: get_config!(:my_app, :env)
  end

Documentation

There's much more use cases on the hexdocs/configex documentation.

Installation

Check out configex version on hex.pm/configex. The package can be installed by adding configex to your list of dependencies in mix.exs:

def deps do
  [
    {:configex, "~> 0.1.1"}
  ]
end

Development

Check out the Makefile for useful development tasks.