Rails application configuration

.env

# .env
# Setup sensitive information using .env file
# It should be added to .gitignore

AWS_ACESS_KEY_ID=
AWS_SECRET_ACCESS_KEY=

application.rb

# config/application.rb

# Rails.configuration is the main place to configure application
# If you need to setup some sensitive information like API keys, setup it with ENV

RailsBase::Application.configure do
  config.carrierwave.storage = :fog
  config.carrierwave.aws_access_key_id = ENV['AWS_ACESS_KEY_ID']
  config.carrierwave.aws_secret_access_key = ENV['AWS_SECRET_ACCESS_KEY']
end

carrierwave.rb

# config/initializers/carrierwave.rb

# Gem initializers should be configured with Rails.configuration
# They should not access ENV directly

CarrierWave.configure do |config|
  config.storage = Rails.configuration.carrierwave.storage

  config.fog_credentials = {
    :provider               => 'AWS',
    :aws_access_key_id      => Rails.configuration.carrierwave.aws_access_key_id,
    :aws_secret_access_key  => Rails.configuration.carrierwave.aws_secret_access_key
  }  
end

Gemfile

gem 'custom_configuration'
gem 'dotenv-rails'

test.rb

# config/environments/test.rb

# Redefine application configuration using Rails configuration 
# file for specific environment

RailsBase::Application.configure do
  config.carrierwave.storage = :file
end