Add metric to track data columns recovered from execution layer (#15924)

beacon-chain/sync/metrics.go

@@ -192,6 +192,13 @@ var (
 		},
 	)
 
+	dataColumnsRecoveredFromELTotal = promauto.NewCounter(
+		prometheus.CounterOpts{
+			Name: "data_columns_recovered_from_el_total",
+			Help: "Count the number of times data columns have been recovered from the execution layer.",
+		},
+	)
+
 	// Data column sidecar validation, beacon metrics specs
 	dataColumnSidecarVerificationRequestsCounter = promauto.NewCounter(prometheus.CounterOpts{
 		Name: "beacon_data_column_sidecar_processing_requests_total",

beacon-chain/sync/subscriber_beacon_blocks.go

@@ -224,6 +224,8 @@ func (s *Service) processDataColumnSidecarsFromExecution(ctx context.Context, so
 			}
 
 			if len(unseenIndices) > 0 {
+				dataColumnsRecoveredFromELTotal.Inc()
+
 				log.WithFields(logrus.Fields{
 					"root":          fmt.Sprintf("%#x", source.Root()),
 					"slot":          source.Slot(),