avg = l.rttMsSum / float64(l.successRequestCount)
	}
	now := time.Now().UTC()
	return Metrics{
		LastReachableSecs:   now.Sub(o.serviceMetrics.LastCheckSuccess).Seconds(),
		LastUnreachableSecs: now.Sub(o.serviceMetrics.LastCheckFailure).Seconds(),
		TotalRequests:       l.failedRequestCount + l.successRequestCount,
		FailedRequests:      l.failedRequestCount,
		AvgSuccRTTMs:        avg,
		MaxSuccRTTMs:        l.maxRttMs,

	if dsecs == "" {
		return defaultExpiry, nil
	}

	d, err := strconv.Atoi(dsecs)
	if err != nil {
		return 0, auth.ErrInvalidDuration
	}

	dur := time.Duration(d) * time.Second

	if dur < minExpiry || dur > maxExpiry {
		return 0, auth.ErrInvalidDuration
	}
	return dur, nil
}

// Lookup returns a new Config by merging the given K/V config
// system with environment variables.