fix(kafka): Set namespace for Loki kafka metrics (#14426)

pkg/distributor/distributor.go

@@ -279,11 +279,13 @@ func New(
 			Help:      "Total number of times the distributor has sharded streams",
 		}),
 		kafkaAppends: promauto.With(registerer).NewCounterVec(prometheus.CounterOpts{
-			Name: "kafka_appends_total",
-			Help: "The total number of appends sent to kafka ingest path.",
+			Namespace: constants.Loki,
+			Name:      "distributor_kafka_appends_total",
+			Help:      "The total number of appends sent to kafka ingest path.",
 		}, []string{"partition", "status"}),
 		kafkaWriteLatency: promauto.With(registerer).NewHistogram(prometheus.HistogramOpts{
-			Name:                            "kafka_latency_seconds",
+			Namespace:                       constants.Loki,
+			Name:                            "distributor_kafka_latency_seconds",
 			Help:                            "Latency to write an incoming request to the ingest storage.",
 			NativeHistogramBucketFactor:     1.1,
 			NativeHistogramMinResetDuration: 1 * time.Hour,
@@ -291,13 +293,15 @@ func New(
 			Buckets:                         prometheus.DefBuckets,
 		}),
 		kafkaWriteBytesTotal: promauto.With(registerer).NewCounter(prometheus.CounterOpts{
-			Name: "kafka_sent_bytes_total",
-			Help: "Total number of bytes sent to the ingest storage.",
+			Namespace: constants.Loki,
+			Name:      "distributor_kafka_sent_bytes_total",
+			Help:      "Total number of bytes sent to the ingest storage.",
 		}),
 		kafkaRecordsPerRequest: promauto.With(registerer).NewHistogram(prometheus.HistogramOpts{
-			Name:    "kafka_records_per_write_request",
-			Help:    "The number of records a single per-partition write request has been split into.",
-			Buckets: prometheus.ExponentialBuckets(1, 2, 8),
+			Namespace: constants.Loki,
+			Name:      "distributor_kafka_records_per_write_request",
+			Help:      "The number of records a single per-partition write request has been split into.",
+			Buckets:   prometheus.ExponentialBuckets(1, 2, 8),
 		}),
 		writeFailuresManager: writefailures.NewManager(logger, registerer, cfg.WriteFailuresLogging, configs, "distributor"),
 		kafkaWriter:          kafkaWriter,

pkg/kafka/writer_client.go

@@ -18,6 +18,8 @@ import (
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/atomic"
+
+	"github.com/grafana/loki/v3/pkg/util/constants"
 )
 
 // NewWriterClient returns the kgo.Client that should be used by the Writer.
@@ -189,6 +191,7 @@ func NewProducer(client *kgo.Client, maxBufferedBytes int64, reg prometheus.Regi
 		// Metrics.
 		bufferedProduceBytes: promauto.With(reg).NewSummary(
 			prometheus.SummaryOpts{
+				Namespace:  constants.Loki,
 				Name:       "buffered_produce_bytes",
 				Help:       "The buffered produce records in bytes. Quantile buckets keep track of buffered records size over the last 60s.",
 				Objectives: map[float64]float64{0.5: 0.05, 0.99: 0.001, 1: 0.001},
@@ -197,16 +200,19 @@ func NewProducer(client *kgo.Client, maxBufferedBytes int64, reg prometheus.Regi
 			}),
 		bufferedProduceBytesLimit: promauto.With(reg).NewGauge(
 			prometheus.GaugeOpts{
-				Name: "buffered_produce_bytes_limit",
-				Help: "The bytes limit on buffered produce records. Produce requests fail once this limit is reached.",
+				Namespace: constants.Loki,
+				Name:      "buffered_produce_bytes_limit",
+				Help:      "The bytes limit on buffered produce records. Produce requests fail once this limit is reached.",
 			}),
 		produceRequestsTotal: promauto.With(reg).NewCounter(prometheus.CounterOpts{
-			Name: "produce_requests_total",
-			Help: "Total number of produce requests issued to Kafka.",
+			Namespace: constants.Loki,
+			Name:      "produce_requests_total",
+			Help:      "Total number of produce requests issued to Kafka.",
 		}),
 		produceFailuresTotal: promauto.With(reg).NewCounterVec(prometheus.CounterOpts{
-			Name: "produce_failures_total",
-			Help: "Total number of failed produce requests issued to Kafka.",
+			Namespace: constants.Loki,
+			Name:      "produce_failures_total",
+			Help:      "Total number of failed produce requests issued to Kafka.",
 		}, []string{"reason"}),
 	}