dotenv

Shim to load environment variables from .env into ENV in development.

Storing configuration in the environment is one of the tenets of a twelve-factor app. Anything that is likely to change between deployment environments–such as resource handles for databases or credentials for external services–should be extracted from the code into environment variables.

But it is not always practical to set environment variables on development machines or continuous integration servers where multiple projects are run. dotenv loads variables from a .env file into ENV when the environment is bootstrapped.

dotenv is intended to be used in development. If you would like to use it in production or other environments, see dotenv-deployment

Installation

Rails

Add this line to the top of your application's Gemfile:

gem 'dotenv-rails', :groups => [:development, :test]

And then execute:

$ bundle

Note on load order

dotenv is initialized in your Rails app during the before_configuration callback, which is fired when the Application constant is defined in config/application.rb with class Application < Rails::Application. If you need it to be initialized sooner, you can manually call Dotenv::Railtie.load.

# config/application.rb
Bundler.require(*Rails.groups)

Dotenv::Railtie.load

HOSTNAME = ENV['HOSTNAME']

If you use gems that require environment variables to be set before they are loaded, then list dotenv-rails in the Gemfile before those other gems and require dotenv/rails-now.

gem 'dotenv-rails', :require => 'dotenv/rails-now'
gem 'gem-that-requires-env-variables'

Sinatra or Plain ol' Ruby

Install the gem:

$ gem install dotenv

As early as possible in your application bootstrap process, load .env:

require 'dotenv'
Dotenv.load

Alternatively, you can use the dotenv executable to launch your application:

$ dotenv ./script.py

To ensure .env is loaded in rake, load the tasks:

require 'dotenv/tasks'

task :mytask => :dotenv do
    # things that require .env
end

Usage

Add your application configuration to your .env file in the root of your project:

S3_BUCKET=YOURS3BUCKET
SECRET_KEY=YOURSECRETKEYGOESHERE

If you need multiline variables, for example private keys, you can double quote strings and use the \n character for newlines:

PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----\nHkVN9…\n-----END DSA PRIVATE KEY-----\n"

You may also add export in front of each line so you can source the file in bash:

export S3_BUCKET=YOURS3BUCKET
export SECRET_KEY=YOURSECRETKEYGOESHERE

Whenever your application loads, these variables will be available in ENV:

config.fog_directory  = ENV['S3_BUCKET']

Should I commit my .env file?

Credentials should only be accessible on the machines that need access to them. Never commit sensitive information to a repository that is not needed by every development machine and server.

Personally, I prefer to commit the .env file with development-only settings. This makes it easy for other developers to get started on the project without compromising credentials for other environments. If you follow this advice, make sure that all the credentials for your development environment are different from your other deployments and that the development credentials do not have access to any confidential data.

Contributing

If you want a better idea of how dotenv works, check out the Ruby Rogues Code Reading of dotenv.

Fork it
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Added some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request