Align metric names with Prometheus naming conventions

Use base units, export cumulative values as _total counters, update docs, dashboards and rules.

metrics/pve_metrics_manager.go

@@ -23,8 +23,8 @@ type PveMetricsManager struct {
 	collectors []PveMetricsCollector // Metrics collector instances.
 	registry   *TTLRegistry          // Registry which handles autoamtic dangling metrics deletion.
 
-	latencySummary *prometheus.SummaryVec // Collection latency summary.
-	interval       int                    // Collection interval.
+	durationSummary *prometheus.SummaryVec // Collection duration summary.
+	interval        int                    // Collection interval.
 
 	stop chan struct{} // Stop channel which is used in ticker.
 }
@@ -80,10 +80,10 @@ func NewPveMetricsManager(apiClient *proxmox.PveApiClient, conf *configuration.P
 		c.RegisterCollector(NewPveVirtualMachineCollector(apiClient, c.registry))
 	}
 
-	// Metrics collection latency summary.
-	c.latencySummary = promauto.NewSummaryVec(prometheus.SummaryOpts{
-		Name: "pve_metrics_collection_latency_ms",
-		Help: "Summary of metrics collection latency milliseconds from PVE API.",
+	// Metrics collection duration summary.
+	c.durationSummary = promauto.NewSummaryVec(prometheus.SummaryOpts{
+		Name: "pve_metrics_collection_duration_seconds",
+		Help: "Summary of the PVE API metrics collection duration in seconds.",
 	}, []string{"collector"})
 
 	c.registry.StartCleanupLoop(5 * time.Second)
@@ -102,7 +102,7 @@ func (c *PveMetricsManager) collectMetrics() {
 		} else {
 			latency := time.Since(start)
 			log.Tracef("Finished collecting '%s' metrics after %s.", collector.GetName(), utils.HumanDuration(latency))
-			c.latencySummary.With(prometheus.Labels{"collector": collector.GetName()}).Observe(float64(latency.Milliseconds()))
+			c.durationSummary.With(prometheus.Labels{"collector": collector.GetName()}).Observe(latency.Seconds())
 		}
 	}
 }