ExConfig

Yet another Elixir app configuration package for fun and profit.

The Mix provides a way to manage your app config, but it works only at compile time (so helps you to develop and test the app), once a build is made Mix.Config no longer takes any action. For new Elixir versions (1.9+) the Config module is moved into Elixir core, but it still gives a very basic functionality.

There are already few packages in Hex which help you get parameters from external sources, like OS level environment variables, or even can populate system configuration storage at start time (so applications can continue use Application.get_env/2-3).

The idea behind this package is to use a regular Elixir module to store and get application parameters. The package provides a set of macros and helpers to easily express configuration your application needs. It also helps to aggregate configuration releated code/parameters into a single place.

Installation

The package can be installed by adding ex_config to your list of dependencies in mix.exs:

def deps do
  [{:ex_config, "~> 0.2"}]
end

Usage

A simple example can look like:

# config/config.exs
use Mix.Config
alias ExConfig.Source.System
config :my_app,
  port: {System, name: "PORT"},
  addr: "127.0.0.1"


# lib/my_app/config.ex
defmodule MyApp.Config do
  # Inject useful macros 
  use ExConfig, otp_app: :my_app

  # Add shorthands for types
  alias ExConfig.Type.{Integer, String}

  # Define config parameters
  env :port, Integer, range: 1..65535, default: 3000
  env :addr, String, default: "*"
  # Define dynamic parameter (just a function)
  dyn :listen_on, do: "#{addr()}:#{port()}"
end

And example how to use it from other modules:

# lib/my_app.ex
defmodule MyApp do
  def start(_, _) do
    HttpServer.start(MyApp.Config.listen_on)
  end
end

Additional examples can be found in example directory.