Rename the tail lag metric to ntfy_tail_messages_lag_seconds

metrics/metrics.go

@@ -96,8 +96,8 @@ var (
 	ClusterLeader = prometheus.NewGauge(prometheus.GaugeOpts{
 		Name: "ntfy_cluster_leader",
 	})
-	TailLagSeconds = prometheus.NewGauge(prometheus.GaugeOpts{
-		Name: "ntfy_tail_lag_seconds", // Age of the newest message of the last read; well above the write delay means it is behind
+	TailMessagesLagSeconds = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_tail_messages_lag_seconds", // Age of the newest message of the last read; well above the write delay means it is behind
 	})
 	TailMessagesRead = prometheus.NewCounter(prometheus.CounterOpts{
 		Name: "ntfy_tail_messages_read_total",
@@ -135,7 +135,7 @@ func init() {
 		ClusterQueueDropped,
 		ClusterMessagesWasted,
 		ClusterLeader,
-		TailLagSeconds,
+		TailMessagesLagSeconds,
 		TailMessagesRead,
 		TailMessagesMissed,
 		Visitors,

metrics/metrics_test.go

@@ -36,7 +36,7 @@ var expectedMetricNames = []string{
 	"ntfy_messages_published_failure",
 	"ntfy_messages_published_success",
 	"ntfy_subscribers_total",
-	"ntfy_tail_lag_seconds",
+	"ntfy_tail_messages_lag_seconds",
 	"ntfy_tail_messages_missed_total",
 	"ntfy_tail_messages_read_total",
 	"ntfy_topics_total",

server/server_tail.go

@@ -30,7 +30,7 @@ func (s *Server) runTail(tail *message.Tail) {
 			continue
 		}
 		metrics.TailMessagesRead.Add(float64(len(messages)))
-		metrics.TailLagSeconds.Set(tailLag(messages, time.Now()).Seconds())
+		metrics.TailMessagesLagSeconds.Set(tailLag(messages, time.Now()).Seconds())
 		s.publishMissed(messages)
 	}
 }