README.md

Brine

Brine is a configuration loader that addresses common problems with configuring Elixir applications so that they are consistent with 12 Factor.

Goals

1. Allow loading of configuration from a variety of sources (eg Environment, File, Etcd)
2. Avoid config per environment pattern
3. Support loading of Elixir terms
4. Be compatible with libraries not using Brine
5. Support autocomplete and compile time checks when retrieving configuration variables
6. Reduce temptation to hardcode variables by lowering friction of adding configuration

Usage

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

def deps do
  [
    {:brine, "~> 0.1.0"}
  ]
end

Create a module to represent all configuration variables with default values

defmodule MyApp.Config do
  use Brine
  
  def config(:myapp, [
    foo: "bar",
    nested: %{
      test: nil
    }
  ])
end

When your application starts load the configuration via a Brine.Loader. Example below uses the Environment Variable Loader. Then you can access the variables by calling the generated function.

MYAPP_NESTED_TEST='Hello' iex -S mix
iex(1)> :ok = MyApp.Config.load(Brine.Loader.Env)
iex(2)> MyApp.Config.myapp_nested_test()
"Hello"

This also works with external libraries.

defmodule MyApp.Config do
  use Brine
  
  def config(:ex_twilio, [
    account_sid: nil,
    auth_token: nil
  ])
end

EX_TWILIO_ACCOUNT_SID=xxxx EX_TWILIO_AUTH_TOKEN=xxxx iex -S mix

Loading Elixir Terms

Brine supports loading Elixir terms so the following is possible

MYAPP_FOO='{:example, 5}' iex -S mix
iex(1)> MyApp.Config.myapp_foo()
{:example, 5}

If the input cannot be parsed, it will assume the input is meant to be a String. However, Elixir by default interprets a term starting with an uppercase letter as a Module. Sometimes this isn't desired but you can coerce it into a string by wrapping it in quotes as shown below

MYAPP_FOO='Hello' iex -S mix
iex(1)> MyApp.Config.myapp_foo()
Hello

MYAPP_FOO='"Hello"' iex -S mix
iex(1)> MyApp.Config.myapp_foo()
"Hello"

Still thinking about a better way to implement this so please open an issue if you have any ideas