mvcc: add "etcd_mvcc_db_total_size_in_bytes"

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

mvcc/metrics.go

@@ -139,7 +139,7 @@ var (
 			Help:      "Total number of db keys compacted.",
 		})
 
-	dbTotalSize = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+	dbTotalSizeDebugging = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
 		Namespace: "etcd_debugging",
 		Subsystem: "mvcc",
 		Name:      "db_total_size_in_bytes",
@@ -151,9 +151,21 @@ var (
 			return reportDbTotalSizeInBytes()
 		},
 	)
+	dbTotalSize = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: "etcd",
+		Subsystem: "mvcc",
+		Name:      "db_total_size_in_bytes",
+		Help:      "Total size of the underlying database in bytes.",
+	},
+		func() float64 {
+			reportDbTotalSizeInBytesMu.RLock()
+			defer reportDbTotalSizeInBytesMu.RUnlock()
+			return reportDbTotalSizeInBytes()
+		},
+	)
 	// overridden by mvcc initialization
 	reportDbTotalSizeInBytesMu sync.RWMutex
-	reportDbTotalSizeInBytes   func() float64 = func() float64 { return 0 }
+	reportDbTotalSizeInBytes   = func() float64 { return 0 }
 )
 
 func init() {
@@ -171,6 +183,7 @@ func init() {
 	prometheus.MustRegister(dbCompactionPauseDurations)
 	prometheus.MustRegister(dbCompactionTotalDurations)
 	prometheus.MustRegister(dbCompactionKeysCounter)
+	prometheus.MustRegister(dbTotalSizeDebugging)
 	prometheus.MustRegister(dbTotalSize)
 }