omniauth.rb

oauth_credentials.yml

development:
  google:
    id: '34234sds343'
    secret: 'drgfr'
  facebook:
    id: '3434'
    secret: 'sds'
  vkontakte:
    id: '132'
    secret: '1212'

omniauth.rb

oauth_config = YAML::load_file("#{Rails.root}/config/oauth_credentials.yml")[Rails.env] rescue fail("#{Rails.root}/config/oauth_credentials.yml for #{Rails.env} not exists!")

Rails.application.config.middleware.use OmniAuth::Builder do
  oauth_config.each do |provider, params|
    provider provider, params['id'], params['secret']
  end
end