udp_queues_linux.go: Expose UDP drops via gauge analogous to queue sizes.

Signed-off-by: Chris Cleeland <[email protected]>

Author: cleeland

collector/udp_queues_linux.go

@@ -62,6 +62,7 @@ func (c *udpQueuesCollector) Update(ch chan<- prometheus.Metric) error {
 	if errIPv4 == nil {
 		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(s4.TxQueueLength), "tx", "v4")
 		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(s4.RxQueueLength), "rx", "v4")
+		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(*s4.Drops), "drops", "v4")
 	} else {
 		if errors.Is(errIPv4, os.ErrNotExist) {
 			level.Debug(c.logger).Log("msg", "not collecting ipv4 based metrics")
@@ -74,6 +75,7 @@ func (c *udpQueuesCollector) Update(ch chan<- prometheus.Metric) error {
 	if errIPv6 == nil {
 		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(s6.TxQueueLength), "tx", "v6")
 		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(s6.RxQueueLength), "rx", "v6")
+		ch <- prometheus.MustNewConstMetric(c.desc, prometheus.GaugeValue, float64(*s6.Drops), "drops", "v6")
 	} else {
 		if errors.Is(errIPv6, os.ErrNotExist) {
 			level.Debug(c.logger).Log("msg", "not collecting ipv6 based metrics")