Set ENV variables for Ruby on Rails

Question

I've followed the steps from this video from railscasts for setting ENV variables.

This is my configuration:

config/database.yml

default: &default
 adapter: mysql2
 encoding: utf8
 pool: 5
 username: <%= ENV['DATABASE_USERNAME'] %>
 password: <%= ENV['DATABASE_PASSWORD'] %>
 socket: /var/run/mysqld/mysqld.sock
development:
 <<: *default
database: <%= ENV['DATABASE_NAME'] %>
test:
 <<: *default
database: <%= ENV['DATABASE_NAME'] %>
production:
 <<: *default
 database: <%= ENV['DATABASE_NAME'] %>
 username: <%= ENV['DATABASE_USERNAME'] %>
password: <%= ENV['DATABASE_PASSWORD'] %>

config/application.rb

config = YAML.load(File.read(File.expand_path('../application.yml', __FILE__)))
config.merge! config.fetch(Rails.env, {})
config.each do |key, value|
 ENV[key] = value.to_s unless value.kind_of? Hash
end

config/application.yml

development:
 DATABASE_USERNAME: "username goes here"
 DATABASE_PASSWORD: "password goes here"
 DATABASE_NAME: "database name goes here"
 SECRET_KEY_BASE: "secret key goes here"
test:
 DATABASE_USERNAME: "username goes here"
 DATABASE_PASSWORD: "password goes here"
 DATABASE_NAME: "database name goes here"
 SECRET_KEY_BASE: "secret key goes here"
production:
 DATABASE_USERNAME: "username goes here"
 DATABASE_PASSWORD: "password goes here"
 DATABASE_NAME: "database name goes here"
 SECRET_KEY_BASE: "secret key goes here"

Does this configuration follow best practices, or need some changes?

• Frederik Spang: Best Practice would be to have ENV Variables from shell. VAR=value rails server.
• Lykos: What if you have different credentials for username and password or database_name configuration ?
• Frederik Spang: What're you thinking? Production/Development?
• Lykos: (in case of setting ENV Variables from shell) what if you have more than one app? I guess the username and password would be the same but the database_name could be different on each case, right?

Answer 1

for what you use config/application.yml instead use config/secrets.yml. It is already implemented in Rails. Than you can fetch your key by:

Rails.application.secrets

even more, add to config/application.rb variable SECRETS = Rails.application.secrets and now you can use it:

SECRETS[:my_secret_key]

read more IN RAILS DOCS

• Lykos: so, everything I have in config/application.yml should move to config/secrets.yml, right? so the ENV variables should be in another .yml file likw I have or in shell ?
• Oleh Sobchuk: yes, move data from application.yml to secret.yml. ENV variables you need in HEROKU, AWS etc, but for example in DigitalOcean or in local server you can work with secrets.yml

Answer 2

An Alternative is ..

Add gem 'config' to your Gemfile and run bundle install to install it. Then run

rails g config:install

which will generate customizable config file config/initializers/config.rb and set of default settings files:

config/settings.yml
config/settings/development.yml
config/settings/production.yml
config/settings/test.yml

You can now edit them to adjust to your needs. a

see the usage in https://github.com/railsconfig/config compatible Rails>= 3.1, 4 and 5