OTLP receiver: Allow colons in non-standard units

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * [CHANGE] Notifier: Increment the prometheus_notifications_errors_total metric by the number of affected alerts rather than by one per batch of affected alerts. #15428
 * [ENHANCEMENT] OTLP receiver: Convert also metric metadata. #15416
+* [BUGFIX] OTLP receiver: Allow colons in non-standard units. #15710
 
 ## 3.0.1 / 2024-11-28
 

storage/remote/otlptranslator/prometheus/normalize_name.go

@@ -22,7 +22,6 @@ import (
 	"strings"
 	"unicode"
 
-	"github.com/prometheus/prometheus/util/strutil"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 )
 
@@ -120,18 +119,19 @@ func BuildCompliantName(metric pmetric.Metric, namespace string, addMetricSuffix
 	return metricName
 }
 
+var nonMetricNameCharRE = regexp.MustCompile(`[^a-zA-Z0-9:]`)
+
 // Build a normalized name for the specified metric.
 func normalizeName(metric pmetric.Metric, namespace string, allowUTF8 bool) string {
 	var nameTokens []string
 	var separators []string
 	if !allowUTF8 {
-		nonTokenMetricCharRE := regexp.MustCompile(`[^a-zA-Z0-9:]`)
 		// Split metric name into "tokens" (of supported metric name runes).
 		// Note that this has the side effect of replacing multiple consecutive underscores with a single underscore.
 		// This is part of the OTel to Prometheus specification: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.38.0/specification/compatibility/prometheus_and_openmetrics.md#otlp-metric-points-to-prometheus.
 		nameTokens = strings.FieldsFunc(
 			metric.Name(),
-			func(r rune) bool { return nonTokenMetricCharRE.MatchString(string(r)) },
+			func(r rune) bool { return nonMetricNameCharRE.MatchString(string(r)) },
 		)
 	} else {
 		translationFunc := func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) && r != ':' }
@@ -229,7 +229,7 @@ func cleanUpUnit(unit string) string {
 	// This is part of the OTel to Prometheus specification: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.38.0/specification/compatibility/prometheus_and_openmetrics.md#otlp-metric-points-to-prometheus.
 	multipleUnderscoresRE := regexp.MustCompile(`__+`)
 	return strings.TrimPrefix(multipleUnderscoresRE.ReplaceAllString(
-		strutil.SanitizeLabelName(unit),
+		nonMetricNameCharRE.ReplaceAllString(unit, "_"),
 		"_",
 	), "_")
 }

storage/remote/otlptranslator/prometheus/normalize_name_test.go

@@ -37,6 +37,8 @@ func TestWhiteSpaces(t *testing.T) {
 
 func TestNonStandardUnit(t *testing.T) {
 	require.Equal(t, "system_network_dropped", normalizeName(createGauge("system.network.dropped", "{packets}"), "", false))
+	// The normal metric name character set is allowed in non-standard units.
+	require.Equal(t, "system_network_dropped_nonstandard:_1", normalizeName(createGauge("system.network.dropped", "nonstandard:_1"), "", false))
 }
 
 func TestNonStandardUnitCounter(t *testing.T) {
@@ -68,6 +70,12 @@ func TestHertz(t *testing.T) {
 func TestPer(t *testing.T) {
 	require.Equal(t, "broken_metric_speed_km_per_hour", normalizeName(createGauge("broken.metric.speed", "km/h"), "", false))
 	require.Equal(t, "astro_light_speed_limit_meters_per_second", normalizeName(createGauge("astro.light.speed_limit", "m/s"), "", false))
+	// The normal metric name character set is allowed in non-standard units.
+	require.Equal(t, "system_network_dropped_non_per_standard:_1", normalizeName(createGauge("system.network.dropped", "non/standard:_1"), "", false))
+
+	t.Run("invalid per unit", func(t *testing.T) {
+		require.Equal(t, "broken_metric_speed_km", normalizeName(createGauge("broken.metric.speed", "km/°"), "", false))
+	})
 }
 
 func TestPercent(t *testing.T) {
@@ -89,7 +97,7 @@ func TestAllowUTF8(t *testing.T) {
 	})
 	t.Run("disallow UTF8", func(t *testing.T) {
 		require.Equal(t, "unsupported_metric_temperature_F", normalizeName(createGauge("unsupported.metric.temperature", "°F"), "", false))
-		require.Equal(t, "unsupported_metric_weird", normalizeName(createGauge("unsupported.metric.weird", "+=.:,!* & #"), "", false))
+		require.Equal(t, "unsupported_metric_weird", normalizeName(createGauge("unsupported.metric.weird", "+=.,!* & #"), "", false))
 		require.Equal(t, "unsupported_metric_redundant_test_per_C", normalizeName(createGauge("unsupported.metric.redundant", "__test $/°C"), "", false))
 		require.Equal(t, "metric_with_foreign_characters", normalizeName(createGauge("metric_with_字符_foreign_characters", "ど"), "", false))
 	})