def apply_system_defaults
      if    @region.nil? && @zone.nil?
        @region, @zone = Rudy::DEFAULT_REGION, Rudy::DEFAULT_ZONE
      elsif @region.nil?
        @region = @zone.to_s.gsub(/[a-z]$/, '').to_sym
      elsif @zone.nil?
        @zone = "#{@region}b".to_sym
      end
      
      @environment ||= Rudy::DEFAULT_ENVIRONMENT
      @role ||= Rudy::DEFAULT_ROLE
      @localhost ||= Rudy.sysinfo.hostname || 'localhost'
      @auto = false if @auto.nil?
    end
def apply_system_defaults
      if    @region.nil? && @zone.nil?
        @region, @zone = Rudy::DEFAULT_REGION, Rudy::DEFAULT_ZONE
      elsif @region.nil?
        @region = @zone.to_s.gsub(/[a-z]$/, '').to_sym
      elsif @zone.nil?
        @zone = "#{@region}b".to_sym
      end
      
      @environment ||= Rudy::DEFAULT_ENVIRONMENT
      @role ||= Rudy::DEFAULT_ROLE
      @localhost ||= Rudy.sysinfo.hostname || 'localhost'
      @auto = false if @auto.nil?
    end
Apply defaults for parameters that must have values