Drop Pending size and count from replication metrics (#12378)

Real-time metrics calculated in-memory rely on the initial
replication metrics saved with data usage. However, this can
lag behind the actual state of the cluster at the time of server 
restart leading to inaccurate Pending size/counts reported to
Prometheus. Dropping the Pending metrics as this can be more 
reliably monitored by applications with replication notifications.

Signed-off-by: Poorna Krishnamoorthy <poorna@minio.io>

cmd/metrics-v2.go

@@ -98,8 +98,6 @@ const (
 	failedCount   MetricName = "failed_count"
 	failedBytes   MetricName = "failed_bytes"
 	freeBytes     MetricName = "free_bytes"
-	pendingBytes  MetricName = "pending_bytes"
-	pendingCount  MetricName = "pending_count"
 	readBytes     MetricName = "read_bytes"
 	rcharBytes    MetricName = "rchar_bytes"
 	receivedBytes MetricName = "received_bytes"
@@ -400,15 +398,7 @@ func getBucketUsageObjectsTotalMD() MetricDescription {
 		Type:      gaugeMetric,
 	}
 }
-func getBucketRepPendingBytesMD() MetricDescription {
-	return MetricDescription{
-		Namespace: bucketMetricNamespace,
-		Subsystem: replicationSubsystem,
-		Name:      pendingBytes,
-		Help:      "Total bytes pending to replicate.",
-		Type:      gaugeMetric,
-	}
-}
+
 func getBucketRepFailedBytesMD() MetricDescription {
 	return MetricDescription{
 		Namespace: bucketMetricNamespace,
@@ -436,15 +426,7 @@ func getBucketRepReceivedBytesMD() MetricDescription {
 		Type:      gaugeMetric,
 	}
 }
-func getBucketRepPendingOperationsMD() MetricDescription {
-	return MetricDescription{
-		Namespace: bucketMetricNamespace,
-		Subsystem: replicationSubsystem,
-		Name:      pendingCount,
-		Help:      "Total number of objects pending replication",
-		Type:      gaugeMetric,
-	}
-}
+
 func getBucketRepFailedOperationsMD() MetricDescription {
 	return MetricDescription{
 		Namespace: bucketMetricNamespace,
@@ -1318,11 +1300,6 @@ func getBucketUsageMetrics() MetricsGroup {
 				})
 
 				if stat.hasReplicationUsage() {
-					metrics = append(metrics, Metric{
-						Description:    getBucketRepPendingBytesMD(),
-						Value:          float64(stat.PendingSize),
-						VariableLabels: map[string]string{"bucket": bucket},
-					})
 					metrics = append(metrics, Metric{
 						Description:    getBucketRepFailedBytesMD(),
 						Value:          float64(stat.FailedSize),
@@ -1338,11 +1315,6 @@ func getBucketUsageMetrics() MetricsGroup {
 						Value:          float64(stat.ReplicaSize),
 						VariableLabels: map[string]string{"bucket": bucket},
 					})
-					metrics = append(metrics, Metric{
-						Description:    getBucketRepPendingOperationsMD(),
-						Value:          float64(stat.PendingCount),
-						VariableLabels: map[string]string{"bucket": bucket},
-					})
 					metrics = append(metrics, Metric{
 						Description:    getBucketRepFailedOperationsMD(),
 						Value:          float64(stat.FailedCount),