Fix relabel processed bug (#2394)

* Fix issue where alloy_prometheus_relabel_metrics_processed was not being incremented.

* Add unit tests

CHANGELOG.md

@@ -14,6 +14,10 @@ Main (unreleased)
 
 - Add support for TLS to `prometheus.write.queue`. (@mattdurham)
 
+### Bugfixes
+
+- Fix issue where `alloy_prometheus_relabel_metrics_processed` was not being incremented. (@mattdurham)
+
 v1.6.0-rc.0
 -----------------
 

internal/component/prometheus/relabel/relabel.go

@@ -243,6 +243,8 @@ func (c *Component) relabel(val float64, lbls labels.Labels) labels.Labels {
 	c.mut.RLock()
 	defer c.mut.RUnlock()
 
+	c.metricsProcessed.Inc()
+
 	globalRef := c.ls.GetOrAddGlobalRefID(lbls)
 	var (
 		relabelled labels.Labels

internal/component/prometheus/relabel/relabel_test.go

@@ -2,6 +2,7 @@ package relabel
 
 import (
 	"fmt"
+	dto "github.com/prometheus/client_model/go"
 	"math"
 	"strconv"
 	"testing"
@@ -111,6 +112,17 @@ func TestLRUNaN(t *testing.T) {
 	require.True(t, relabeller.cache.Len() == 0)
 }
 
+func TestMetrics(t *testing.T) {
+	relabeller := generateRelabel(t)
+	lbls := labels.FromStrings("__address__", "localhost")
+
+	relabeller.relabel(0, lbls)
+	m := &dto.Metric{}
+	err := relabeller.metricsProcessed.Write(m)
+	require.NoError(t, err)
+	require.True(t, *(m.Counter.Value) == 1)
+}
+
 func BenchmarkCache(b *testing.B) {
 	ls := labelstore.New(nil, prom.DefaultRegisterer)
 	fanout := prometheus.NewInterceptor(nil, ls, prometheus.WithAppendHook(func(ref storage.SeriesRef, l labels.Labels, _ int64, _ float64, _ storage.Appender) (storage.SeriesRef, error) {