chore(otel): Push a metric for Loki exporter (#17521)

pkg/loghttp/push/otlp.go

@@ -112,6 +112,9 @@ func otlpToLokiPushRequest(ctx context.Context, ld plog.Logs, userID string, otl
 	rls := ld.ResourceLogs()
 	pushRequestsByStream := make(map[string]logproto.Stream, rls.Len())
 
+	// Track if request used the Loki OTLP exporter label
+	var usingLokiExporter bool
+
 	for i := 0; i < rls.Len(); i++ {
 		sls := rls.At(i).ScopeLogs()
 		res := rls.At(i).Resource()
@@ -206,6 +209,11 @@ func otlpToLokiPushRequest(ctx context.Context, ld plog.Logs, userID string, otl
 		retentionPeriodForUser := streamResolver.RetentionPeriodFor(lbs)
 		policy := streamResolver.PolicyFor(lbs)
 
+		// Check if the stream has the exporter=OTLP label; set flag instead of incrementing per stream
+		if value, ok := streamLabels[model.LabelName("exporter")]; ok && value == "OTLP" {
+			usingLokiExporter = true
+		}
+
 		if _, ok := stats.StructuredMetadataBytes[policy]; !ok {
 			stats.StructuredMetadataBytes[policy] = make(map[time.Duration]int64)
 		}
@@ -369,6 +377,11 @@ func otlpToLokiPushRequest(ctx context.Context, ld plog.Logs, userID string, otl
 		}
 	}
 
+	// Increment exporter streams metric once per request if seen
+	if usingLokiExporter {
+		otlpExporterStreams.WithLabelValues(userID).Inc()
+	}
+
 	return pr
 }
 

pkg/loghttp/push/push.go

@@ -57,6 +57,12 @@ var (
 		Help:      "The total number of lines received per tenant",
 	}, []string{"tenant", "aggregated_metric", "policy"})
 
+	otlpExporterStreams = promauto.NewCounterVec(prometheus.CounterOpts{
+		Namespace: constants.Loki,
+		Name:      "distributor_otlp_exporter_streams_total",
+		Help:      "The total number of streams with exporter=OTLP label",
+	}, []string{"tenant"})
+
 	bytesReceivedStats                   = analytics.NewCounter("distributor_bytes_received")
 	structuredMetadataBytesReceivedStats = analytics.NewCounter("distributor_structured_metadata_bytes_received")
 	linesReceivedStats                   = analytics.NewCounter("distributor_lines_received")