Elixir has an excellent configuration system and this dotenv implementation has a serious limitation in that it isn't available at compile time. It fits very poorly into a typical deployment setup using exrm or similar. Configuration management should be built around Elixir's existing system, not environment variables.

A good example is Phoenix which generates a project where the production config imports the "secrets" from a file stored outside of version control. Even if you're using this for development, the same approach could be taken.

If you're sure this is the correct solution to a problem in your development/deployment workflow, read on!

This is a port of @bkeepers' dotenv project to Elixir. You can read more about dotenv on that project's page. The short version is that it simplifies developing projects where configuration is stored in environment variables (e.g. projects intended to be deployed to Heroku).

The simplest way to use Dotenv is with the included OTP application. This will automatically load variables from a .env file in the root of your project directory into the process environment when started.

First add dotenv to your dependencies.

For the latest release:

{:dotenv, "~> 3.0.0"}

For master:

{:dotenv, github: "avdi/dotenv_elixir"}

Fetch your dependencies with mix deps.get.

Now, add the :dotenv application to your applications list when running in the :dev environment:

# Configuration for the OTP application
def application do
  [
    mod: { YourApp, [] },
    applications: app_list(Mix.env)
  ]
end

defp app_list(:dev), do: [:dotenv | app_list]
defp app_list(_), do: app_list
defp app_list, do: [...]

Now, when you load your app in a console with iex -S mix, your environment variables will be set automatically.

The Dotenv.reload!/0 function will reload the variables defined in the .env file.

More examples of the server API usage can be found in dotenv_app_test.exs.

If you would like finer-grained control over when variables are loaded, or would like to inspect them, Dotenv also provides a serverless API for interacting with .env files.

The load!/1 function loads variables into the process environment, and can be passed a path or list of paths to read from.

Alternately, load/1 will return a data structure of the variables read from the .env file:

iex(1)> Dotenv.load
%Dotenv.Env{paths: ["/elixir/dotenv_elixir/.env"],
 values: %{"APP_TEST_VAR" => "HELLO"}}

For further details, see the inline documentation. Usage examples can be found in dotenv_test.exs.