plan

var (
	ErrDrainDeleteConflict           = fmt.Errorf("spec.drain cannot specify both deleteEmptydirData and deleteLocalData")
	ErrDrainPodSelectorNotSelectable = fmt.Errorf("spec.drain.podSelector is not selectable")

	PollingInterval = func(defaultValue time.Duration) time.Duration {
		if str, ok := os.LookupEnv("SYSTEM_UPGRADE_PLAN_POLLING_INTERVAL"); ok {
			if d, err := time.ParseDuration(str); err != nil {
				logrus.Errorf("failed to parse $%s: %v", "SYSTEM_UPGRADE_PLAN_POLLING_INTERVAL", err)
			} else if d > time.Minute {
				return d
			}
		}
		return defaultValue
	}(defaultPollingInterval)
)