Shim to load environment variables from
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.
Add this line to the top of your application's Gemfile:
gem 'dotenv-rails', :groups => [:development, :test]
And then execute:
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
class Application < Rails::Application. If you need it to be initialized sooner, you can manually call
# 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
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
require 'dotenv' Dotenv.load
Alternatively, you can use the
dotenv executable to launch your application:
$ dotenv ./script.py
.env is loaded in rake, load the tasks:
require 'dotenv/tasks' task :mytask => :dotenv do # things that require .env end
Add your application configuration to your
.env file in the root of your project:
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 need to add the output of a command in one of your variables? Simply add it with
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
config.fog_directory = ENV['S3_BUCKET']
Comments may be added to your file as such:
# This is a comment SECRET_KEY=YOURSECRETKEYGOESHERE # comment SECRET_HASH="something-with-a-#-hash"
Variable names may not contain the
# symbol. Values can use the
# if they are enclosed in quotes.
Multiple Rails Environments
dotenv was originally created to load configuration variables into
ENV in development. There are typically better ways to manage configuration in production environments - such as
/etc/environment managed by Puppet or Chef,
heroku config, etc.
However, some find dotenv to be a convenient way to configure Rails applications in staging and production environments, and you can do that by defining environment-specific files like
You can also use
.env.local for local overrides.
If you use this gem to handle env vars for multiple Rails environments (development, test, production, etc.), please note that env vars that are general to all environments should be stored in
.env. Then, environment specific env vars should be stored in
.env.<that environment's name>. When you load a certain environment, dotenv will first load general env vars from
.env, then load environment specific env vars from
.env.<current environment>. Variables defined in
.env.<current environment> will override any values set in
.env or already defined in the environment.
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.
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