Carrierwave + Selectel

carrierwave.rb

CarrierWave.configure do |config|
  if Rails.env.development? || Rails.env.test?
    config.storage = :file
  else
    config.storage = :fog
    config.fog_credentials = {
        :provider               => 'OpenStack',
        :openstack_auth_url     => 'https://auth.selcdn.ru/v1.0',
        :openstack_username     => Rails.application.secrets.openstack_username,
        :openstack_api_key      => Rails.application.secrets.openstack_api_key
    }
    config.fog_directory  = Rails.application.secrets.container  # required
    config.fog_public     = true                                 # optional, defaults to true
    config.fog_attributes = {'Cache-Control'=>'max-age=315576000'}  # optional, defaults to {}
  end
end

I updated the credentials to work with latest fog-openstack version and v2 or v3 OpenStack Keystone auth on Selectel https://gist.github.com/leemour/1cba4aa37da14136731259b9e8fb11a5.