# File lib/fog/openstack.rb, line 145
    def self.authenticate(options, connection_options = {})
      case options[:openstack_auth_uri].path
      when /v1(\.\d+)?/
        authenticate_v1(options, connection_options)
      when /v2(\.\d+)?/
        authenticate_v2(options, connection_options)
      when /v3(\.\d+)?/
        authenticate_v3(options, connection_options)
      else
        authenticate_v2(options, connection_options)
      end
    end