ch <- prometheus.MustNewConstMetric(
		prometheus.NewDesc(
			prometheus.BuildFQName(minioNamespace, "nodes", "online"),
			"Total number of MinIO nodes online",
			nil, nil),
		prometheus.GaugeValue,
		float64(nodesUp),
	)
	ch <- prometheus.MustNewConstMetric(
		prometheus.NewDesc(
			prometheus.BuildFQName(minioNamespace, "nodes", "offline"),
			"Total number of MinIO nodes offline",
			nil, nil),

	for _, label := range md.VariableLabels {
		md.labelSet[label] = struct{}{}
	}
	return md.labelSet
}

func (md *MetricDescriptor) toPromName(namePrefix string) string {
	return prometheus.BuildFQName(namePrefix, "", string(md.Name))
}

func (md *MetricDescriptor) toPromDesc(namePrefix string, extraLabels map[string]string) *prometheus.Desc {
	return prometheus.NewDesc(
		md.toPromName(namePrefix),
		md.Help,

		if metric.Histogram == nil {
			return
		}
		for k, v := range metric.Histogram {
			pmetric, err := prometheus.NewConstMetric(
				prometheus.NewDesc(
					prometheus.BuildFQName(string(metric.Description.Namespace),
						string(metric.Description.Subsystem),
						string(metric.Description.Name)),
					metric.Description.Help,
					append(labels, metric.HistogramBucketLabel),