Bump OTel Collector dependency to v0.88.0

I initially didn't copy the otlptranslator/prometheus folder because I
assumed it wouldn't get changes. But it did. So this PR fixes that and
updates the Collector version.

Supersedes: https://github.com/prometheus/prometheus/pull/12809

Signed-off-by: Goutham <gouthamve@gmail.com>

go.mod

@@ -55,6 +55,7 @@ require (
 	github.com/shurcooL/httpfs v0.0.0-20230704072500-f1e31cf0ba5c
 	github.com/stretchr/testify v1.8.4
 	github.com/vultr/govultr/v2 v2.17.2
+	go.opentelemetry.io/collector/featuregate v0.77.0
 	go.opentelemetry.io/collector/pdata v1.0.0-rcv0017
 	go.opentelemetry.io/collector/semconv v0.88.0
 	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.45.0

go.sum

@@ -760,6 +760,8 @@ go.opencensus.io v0.22.3/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.22.4/go.mod h1:yxeiOL68Rb0Xd1ddK5vPZ/oVn4vY4Ynel7k9FzqtOIw=
 go.opencensus.io v0.24.0 h1:y73uSU6J157QMP2kn2r30vwW1A2W2WFwSCGnAVxeaD0=
 go.opencensus.io v0.24.0/go.mod h1:vNK8G9p7aAivkbmorf4v+7Hgx+Zs0yY+0fOtgBfjQKo=
+go.opentelemetry.io/collector/featuregate v0.77.0 h1:m1/IzaXoQh6SgF6CM80vrBOCf5zSJ2GVISfA27fYzGU=
+go.opentelemetry.io/collector/featuregate v0.77.0/go.mod h1:/kVAsGUCyJXIDSgHftCN63QiwAEVHRLX2Kh/S+dqgHY=
 go.opentelemetry.io/collector/pdata v1.0.0-rcv0017 h1:AgALhc2VenoA5l1DvTdg7mkzaBGqoTSuMkAtjsttBFo=
 go.opentelemetry.io/collector/pdata v1.0.0-rcv0017/go.mod h1:Rv9fOclA5AtM/JGm0d4jBOIAo1+jBA13UT5Bx0ovXi4=
 go.opentelemetry.io/collector/semconv v0.88.0 h1:8TVP4hYaUC87S6CCLKNoSxsUE0ChldE4vqotvNHHUnE=

storage/remote/otlptranslator/prometheus/normalize_label.go

@@ -1,21 +1,31 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package normalize
+package prometheus // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 
 import (
 	"strings"
 	"unicode"
+
+	"go.opentelemetry.io/collector/featuregate"
 )
 
-// Normalizes the specified label to follow Prometheus label names standard.
+var dropSanitizationGate = featuregate.GlobalRegistry().MustRegister(
+	"pkg.translator.prometheus.PermissiveLabelSanitization",
+	featuregate.StageAlpha,
+	featuregate.WithRegisterDescription("Controls whether to change labels starting with '_' to 'key_'."),
+	featuregate.WithRegisterReferenceURL("https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/8950"),
+)
+
+// Normalizes the specified label to follow Prometheus label names standard
 //
 // See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
 //
-// Labels that start with non-letter rune will be prefixed with "key_".
+// Labels that start with non-letter rune will be prefixed with "key_"
 //
-// Exception is made for double-underscores which are allowed.
+// Exception is made for double-underscores which are allowed
 func NormalizeLabel(label string) string {
+
 	// Trivial case
 	if len(label) == 0 {
 		return label
@@ -27,12 +37,14 @@ func NormalizeLabel(label string) string {
 	// If label starts with a number, prepend with "key_"
 	if unicode.IsDigit(rune(label[0])) {
 		label = "key_" + label
+	} else if strings.HasPrefix(label, "_") && !strings.HasPrefix(label, "__") && !dropSanitizationGate.IsEnabled() {
+		label = "key" + label
 	}
 
 	return label
 }
 
-// Return '_' for anything non-alphanumeric.
+// Return '_' for anything non-alphanumeric
 func sanitizeRune(r rune) rune {
 	if unicode.IsLetter(r) || unicode.IsDigit(r) {
 		return r

storage/remote/otlptranslator/prometheus/normalize_label_test.go

@@ -1,19 +0,0 @@
-// Copyright The OpenTelemetry Authors
-// SPDX-License-Identifier: Apache-2.0
-
-package normalize
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TestSanitizeDropSanitization(t *testing.T) {
-	require.Equal(t, "", NormalizeLabel(""))
-	require.Equal(t, "_test", NormalizeLabel("_test"))
-	require.Equal(t, "key_0test", NormalizeLabel("0test"))
-	require.Equal(t, "test", NormalizeLabel("test"))
-	require.Equal(t, "test__", NormalizeLabel("test_/"))
-	require.Equal(t, "__test", NormalizeLabel("__test"))
-}

storage/remote/otlptranslator/prometheus/normalize_name.go

@@ -1,21 +1,23 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package normalize
+package prometheus // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
 
 import (
 	"strings"
 	"unicode"
 
+	"go.opentelemetry.io/collector/featuregate"
 	"go.opentelemetry.io/collector/pdata/pmetric"
 )
 
-// The map to translate OTLP units to Prometheus units.
+// The map to translate OTLP units to Prometheus units
 // OTLP metrics use the c/s notation as specified at https://ucum.org/ucum.html
 // (See also https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/metrics/semantic_conventions/README.md#instrument-units)
 // Prometheus best practices for units: https://prometheus.io/docs/practices/naming/#base-units
 // OpenMetrics specification for units: https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#units-and-base-units
 var unitMap = map[string]string{
+
 	// Time
 	"d":   "days",
 	"h":   "hours",
@@ -35,11 +37,6 @@ var unitMap = map[string]string{
 	"MBy":  "megabytes",
 	"GBy":  "gigabytes",
 	"TBy":  "terabytes",
-	"B":    "bytes",
-	"KB":   "kilobytes",
-	"MB":   "megabytes",
-	"GB":   "gigabytes",
-	"TB":   "terabytes",
 
 	// SI
 	"m": "meters",
@@ -54,11 +51,10 @@ var unitMap = map[string]string{
 	"Hz":  "hertz",
 	"1":   "",
 	"%":   "percent",
-	"$":   "dollars",
 }
 
-// The map that translates the "per" unit.
+// The map that translates the "per" unit
-// Example: s => per second (singular).
+// Example: s => per second (singular)
 var perUnitMap = map[string]string{
 	"s":  "second",
 	"m":  "minute",
@@ -69,7 +65,14 @@ var perUnitMap = map[string]string{
 	"y":  "year",
 }
 
-// Build a Prometheus-compliant metric name for the specified metric.
+var normalizeNameGate = featuregate.GlobalRegistry().MustRegister(
+	"pkg.translator.prometheus.NormalizeName",
+	featuregate.StageBeta,
+	featuregate.WithRegisterDescription("Controls whether metrics names are automatically normalized to follow Prometheus naming convention"),
+	featuregate.WithRegisterReferenceURL("https://github.com/open-telemetry/opentelemetry-collector-contrib/issues/8950"),
+)
+
+// BuildCompliantName builds a Prometheus-compliant metric name for the specified metric
 //
 // Metric name is prefixed with specified namespace and underscore (if any).
 // Namespace is not cleaned up. Make sure specified namespace follows Prometheus
@@ -77,7 +80,33 @@ var perUnitMap = map[string]string{
 //
 // See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
 // and https://prometheus.io/docs/practices/naming/#metric-and-label-naming
-func BuildPromCompliantName(metric pmetric.Metric, namespace string) string {
+func BuildCompliantName(metric pmetric.Metric, namespace string, addMetricSuffixes bool) string {
+	var metricName string
+
+	// Full normalization following standard Prometheus naming conventions
+	if addMetricSuffixes && normalizeNameGate.IsEnabled() {
+		return normalizeName(metric, namespace)
+	}
+
+	// Simple case (no full normalization, no units, etc.), we simply trim out forbidden chars
+	metricName = RemovePromForbiddenRunes(metric.Name())
+
+	// Namespace?
+	if namespace != "" {
+		return namespace + "_" + metricName
+	}
+
+	// Metric name starts with a digit? Prefix it with an underscore
+	if metricName != "" && unicode.IsDigit(rune(metricName[0])) {
+		metricName = "_" + metricName
+	}
+
+	return metricName
+}
+
+// Build a normalized name for the specified metric
+func normalizeName(metric pmetric.Metric, namespace string) string {
+
 	// Split metric name in "tokens" (remove all non-alphanumeric)
 	nameTokens := strings.FieldsFunc(
 		metric.Name(),
@@ -202,7 +231,7 @@ func removeSuffix(tokens []string, suffix string) []string {
 	return tokens
 }
 
-// Clean up specified string so it's Prometheus compliant.
+// Clean up specified string so it's Prometheus compliant
 func CleanUpString(s string) string {
 	return strings.Join(strings.FieldsFunc(s, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) }), "_")
 }
@@ -211,8 +240,8 @@ func RemovePromForbiddenRunes(s string) string {
 	return strings.Join(strings.FieldsFunc(s, func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) && r != '_' && r != ':' }), "_")
 }
 
-// Retrieve the Prometheus "basic" unit corresponding to the specified "basic" unit.
+// Retrieve the Prometheus "basic" unit corresponding to the specified "basic" unit
-// Returns the specified unit if not found in unitMap.
+// Returns the specified unit if not found in unitMap
 func unitMapGetOrDefault(unit string) string {
 	if promUnit, ok := unitMap[unit]; ok {
 		return promUnit
@@ -220,8 +249,8 @@ func unitMapGetOrDefault(unit string) string {
 	return unit
 }
 
-// Retrieve the Prometheus "per" unit corresponding to the specified "per" unit.
+// Retrieve the Prometheus "per" unit corresponding to the specified "per" unit
-// Returns the specified unit if not found in perUnitMap.
+// Returns the specified unit if not found in perUnitMap
 func perUnitMapGetOrDefault(perUnit string) string {
 	if promPerUnit, ok := perUnitMap[perUnit]; ok {
 		return promPerUnit
@@ -229,7 +258,7 @@ func perUnitMapGetOrDefault(perUnit string) string {
 	return perUnit
 }
 
-// Returns whether the slice contains the specified value.
+// Returns whether the slice contains the specified value
 func contains(slice []string, value string) bool {
 	for _, sliceEntry := range slice {
 		if sliceEntry == value {
@@ -239,7 +268,7 @@ func contains(slice []string, value string) bool {
 	return false
 }
 
-// Remove the specified value from the slice.
+// Remove the specified value from the slice
 func removeItem(slice []string, value string) []string {
 	newSlice := make([]string, 0, len(slice))
 	for _, sliceEntry := range slice {

storage/remote/otlptranslator/prometheus/normalize_name_test.go

@@ -1,180 +0,0 @@
-// Copyright The OpenTelemetry Authors
-// SPDX-License-Identifier: Apache-2.0
-
-package normalize
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/require"
-	"go.opentelemetry.io/collector/pdata/pmetric"
-)
-
-func TestByte(t *testing.T) {
-	require.Equal(t, "system_filesystem_usage_bytes", BuildPromCompliantName(createGauge("system.filesystem.usage", "By"), ""))
-}
-
-func TestByteCounter(t *testing.T) {
-	require.Equal(t, "system_io_bytes_total", BuildPromCompliantName(createCounter("system.io", "By"), ""))
-	require.Equal(t, "network_transmitted_bytes_total", BuildPromCompliantName(createCounter("network_transmitted_bytes_total", "By"), ""))
-}
-
-func TestWhiteSpaces(t *testing.T) {
-	require.Equal(t, "system_filesystem_usage_bytes", BuildPromCompliantName(createGauge("\t system.filesystem.usage       ", "  By\t"), ""))
-}
-
-func TestNonStandardUnit(t *testing.T) {
-	require.Equal(t, "system_network_dropped", BuildPromCompliantName(createGauge("system.network.dropped", "{packets}"), ""))
-}
-
-func TestNonStandardUnitCounter(t *testing.T) {
-	require.Equal(t, "system_network_dropped_total", BuildPromCompliantName(createCounter("system.network.dropped", "{packets}"), ""))
-}
-
-func TestBrokenUnit(t *testing.T) {
-	require.Equal(t, "system_network_dropped_packets", BuildPromCompliantName(createGauge("system.network.dropped", "packets"), ""))
-	require.Equal(t, "system_network_packets_dropped", BuildPromCompliantName(createGauge("system.network.packets.dropped", "packets"), ""))
-	require.Equal(t, "system_network_packets", BuildPromCompliantName(createGauge("system.network.packets", "packets"), ""))
-}
-
-func TestBrokenUnitCounter(t *testing.T) {
-	require.Equal(t, "system_network_dropped_packets_total", BuildPromCompliantName(createCounter("system.network.dropped", "packets"), ""))
-	require.Equal(t, "system_network_packets_dropped_total", BuildPromCompliantName(createCounter("system.network.packets.dropped", "packets"), ""))
-	require.Equal(t, "system_network_packets_total", BuildPromCompliantName(createCounter("system.network.packets", "packets"), ""))
-}
-
-func TestRatio(t *testing.T) {
-	require.Equal(t, "hw_gpu_memory_utilization_ratio", BuildPromCompliantName(createGauge("hw.gpu.memory.utilization", "1"), ""))
-	require.Equal(t, "hw_fan_speed_ratio", BuildPromCompliantName(createGauge("hw.fan.speed_ratio", "1"), ""))
-	require.Equal(t, "objects_total", BuildPromCompliantName(createCounter("objects", "1"), ""))
-}
-
-func TestHertz(t *testing.T) {
-	require.Equal(t, "hw_cpu_speed_limit_hertz", BuildPromCompliantName(createGauge("hw.cpu.speed_limit", "Hz"), ""))
-}
-
-func TestPer(t *testing.T) {
-	require.Equal(t, "broken_metric_speed_km_per_hour", BuildPromCompliantName(createGauge("broken.metric.speed", "km/h"), ""))
-	require.Equal(t, "astro_light_speed_limit_meters_per_second", BuildPromCompliantName(createGauge("astro.light.speed_limit", "m/s"), ""))
-}
-
-func TestPercent(t *testing.T) {
-	require.Equal(t, "broken_metric_success_ratio_percent", BuildPromCompliantName(createGauge("broken.metric.success_ratio", "%"), ""))
-	require.Equal(t, "broken_metric_success_percent", BuildPromCompliantName(createGauge("broken.metric.success_percent", "%"), ""))
-}
-
-func TestDollar(t *testing.T) {
-	require.Equal(t, "crypto_bitcoin_value_dollars", BuildPromCompliantName(createGauge("crypto.bitcoin.value", "$"), ""))
-	require.Equal(t, "crypto_bitcoin_value_dollars", BuildPromCompliantName(createGauge("crypto.bitcoin.value.dollars", "$"), ""))
-}
-
-func TestEmpty(t *testing.T) {
-	require.Equal(t, "test_metric_no_unit", BuildPromCompliantName(createGauge("test.metric.no_unit", ""), ""))
-	require.Equal(t, "test_metric_spaces", BuildPromCompliantName(createGauge("test.metric.spaces", "   \t  "), ""))
-}
-
-func TestUnsupportedRunes(t *testing.T) {
-	require.Equal(t, "unsupported_metric_temperature_F", BuildPromCompliantName(createGauge("unsupported.metric.temperature", "°F"), ""))
-	require.Equal(t, "unsupported_metric_weird", BuildPromCompliantName(createGauge("unsupported.metric.weird", "+=.:,!* & #"), ""))
-	require.Equal(t, "unsupported_metric_redundant_test_per_C", BuildPromCompliantName(createGauge("unsupported.metric.redundant", "__test $/°C"), ""))
-}
-
-func TestOtelReceivers(t *testing.T) {
-	require.Equal(t, "active_directory_ds_replication_network_io_bytes_total", BuildPromCompliantName(createCounter("active_directory.ds.replication.network.io", "By"), ""))
-	require.Equal(t, "active_directory_ds_replication_sync_object_pending_total", BuildPromCompliantName(createCounter("active_directory.ds.replication.sync.object.pending", "{objects}"), ""))
-	require.Equal(t, "active_directory_ds_replication_object_rate_per_second", BuildPromCompliantName(createGauge("active_directory.ds.replication.object.rate", "{objects}/s"), ""))
-	require.Equal(t, "active_directory_ds_name_cache_hit_rate_percent", BuildPromCompliantName(createGauge("active_directory.ds.name_cache.hit_rate", "%"), ""))
-	require.Equal(t, "active_directory_ds_ldap_bind_last_successful_time_milliseconds", BuildPromCompliantName(createGauge("active_directory.ds.ldap.bind.last_successful.time", "ms"), ""))
-	require.Equal(t, "apache_current_connections", BuildPromCompliantName(createGauge("apache.current_connections", "connections"), ""))
-	require.Equal(t, "apache_workers_connections", BuildPromCompliantName(createGauge("apache.workers", "connections"), ""))
-	require.Equal(t, "apache_requests_total", BuildPromCompliantName(createCounter("apache.requests", "1"), ""))
-	require.Equal(t, "bigip_virtual_server_request_count_total", BuildPromCompliantName(createCounter("bigip.virtual_server.request.count", "{requests}"), ""))
-	require.Equal(t, "system_cpu_utilization_ratio", BuildPromCompliantName(createGauge("system.cpu.utilization", "1"), ""))
-	require.Equal(t, "system_disk_operation_time_seconds_total", BuildPromCompliantName(createCounter("system.disk.operation_time", "s"), ""))
-	require.Equal(t, "system_cpu_load_average_15m_ratio", BuildPromCompliantName(createGauge("system.cpu.load_average.15m", "1"), ""))
-	require.Equal(t, "memcached_operation_hit_ratio_percent", BuildPromCompliantName(createGauge("memcached.operation_hit_ratio", "%"), ""))
-	require.Equal(t, "mongodbatlas_process_asserts_per_second", BuildPromCompliantName(createGauge("mongodbatlas.process.asserts", "{assertions}/s"), ""))
-	require.Equal(t, "mongodbatlas_process_journaling_data_files_mebibytes", BuildPromCompliantName(createGauge("mongodbatlas.process.journaling.data_files", "MiBy"), ""))
-	require.Equal(t, "mongodbatlas_process_network_io_bytes_per_second", BuildPromCompliantName(createGauge("mongodbatlas.process.network.io", "By/s"), ""))
-	require.Equal(t, "mongodbatlas_process_oplog_rate_gibibytes_per_hour", BuildPromCompliantName(createGauge("mongodbatlas.process.oplog.rate", "GiBy/h"), ""))
-	require.Equal(t, "mongodbatlas_process_db_query_targeting_scanned_per_returned", BuildPromCompliantName(createGauge("mongodbatlas.process.db.query_targeting.scanned_per_returned", "{scanned}/{returned}"), ""))
-	require.Equal(t, "nginx_requests", BuildPromCompliantName(createGauge("nginx.requests", "requests"), ""))
-	require.Equal(t, "nginx_connections_accepted", BuildPromCompliantName(createGauge("nginx.connections_accepted", "connections"), ""))
-	require.Equal(t, "nsxt_node_memory_usage_kilobytes", BuildPromCompliantName(createGauge("nsxt.node.memory.usage", "KBy"), ""))
-	require.Equal(t, "redis_latest_fork_microseconds", BuildPromCompliantName(createGauge("redis.latest_fork", "us"), ""))
-}
-
-func TestTrimPromSuffixes(t *testing.T) {
-	require.Equal(t, "active_directory_ds_replication_network_io", TrimPromSuffixes("active_directory_ds_replication_network_io_bytes_total", pmetric.MetricTypeSum, "bytes"))
-	require.Equal(t, "active_directory_ds_name_cache_hit_rate", TrimPromSuffixes("active_directory_ds_name_cache_hit_rate_percent", pmetric.MetricTypeGauge, "percent"))
-	require.Equal(t, "active_directory_ds_ldap_bind_last_successful_time", TrimPromSuffixes("active_directory_ds_ldap_bind_last_successful_time_milliseconds", pmetric.MetricTypeGauge, "milliseconds"))
-	require.Equal(t, "apache_requests", TrimPromSuffixes("apache_requests_total", pmetric.MetricTypeSum, "1"))
-	require.Equal(t, "system_cpu_utilization", TrimPromSuffixes("system_cpu_utilization_ratio", pmetric.MetricTypeGauge, "ratio"))
-	require.Equal(t, "mongodbatlas_process_journaling_data_files", TrimPromSuffixes("mongodbatlas_process_journaling_data_files_mebibytes", pmetric.MetricTypeGauge, "mebibytes"))
-	require.Equal(t, "mongodbatlas_process_network_io", TrimPromSuffixes("mongodbatlas_process_network_io_bytes_per_second", pmetric.MetricTypeGauge, "bytes_per_second"))
-	require.Equal(t, "mongodbatlas_process_oplog_rate", TrimPromSuffixes("mongodbatlas_process_oplog_rate_gibibytes_per_hour", pmetric.MetricTypeGauge, "gibibytes_per_hour"))
-	require.Equal(t, "nsxt_node_memory_usage", TrimPromSuffixes("nsxt_node_memory_usage_kilobytes", pmetric.MetricTypeGauge, "kilobytes"))
-	require.Equal(t, "redis_latest_fork", TrimPromSuffixes("redis_latest_fork_microseconds", pmetric.MetricTypeGauge, "microseconds"))
-	require.Equal(t, "up", TrimPromSuffixes("up", pmetric.MetricTypeGauge, ""))
-
-	// These are not necessarily valid OM units, only tested for the sake of completeness.
-	require.Equal(t, "active_directory_ds_replication_sync_object_pending", TrimPromSuffixes("active_directory_ds_replication_sync_object_pending_total", pmetric.MetricTypeSum, "{objects}"))
-	require.Equal(t, "apache_current", TrimPromSuffixes("apache_current_connections", pmetric.MetricTypeGauge, "connections"))
-	require.Equal(t, "bigip_virtual_server_request_count", TrimPromSuffixes("bigip_virtual_server_request_count_total", pmetric.MetricTypeSum, "{requests}"))
-	require.Equal(t, "mongodbatlas_process_db_query_targeting_scanned_per_returned", TrimPromSuffixes("mongodbatlas_process_db_query_targeting_scanned_per_returned", pmetric.MetricTypeGauge, "{scanned}/{returned}"))
-	require.Equal(t, "nginx_connections_accepted", TrimPromSuffixes("nginx_connections_accepted", pmetric.MetricTypeGauge, "connections"))
-	require.Equal(t, "apache_workers", TrimPromSuffixes("apache_workers_connections", pmetric.MetricTypeGauge, "connections"))
-	require.Equal(t, "nginx", TrimPromSuffixes("nginx_requests", pmetric.MetricTypeGauge, "requests"))
-
-	// Units shouldn't be trimmed if the unit is not a direct match with the suffix, i.e, a suffix "_seconds" shouldn't be removed if unit is "sec" or "s"
-	require.Equal(t, "system_cpu_load_average_15m_ratio", TrimPromSuffixes("system_cpu_load_average_15m_ratio", pmetric.MetricTypeGauge, "1"))
-	require.Equal(t, "mongodbatlas_process_asserts_per_second", TrimPromSuffixes("mongodbatlas_process_asserts_per_second", pmetric.MetricTypeGauge, "{assertions}/s"))
-	require.Equal(t, "memcached_operation_hit_ratio_percent", TrimPromSuffixes("memcached_operation_hit_ratio_percent", pmetric.MetricTypeGauge, "%"))
-	require.Equal(t, "active_directory_ds_replication_object_rate_per_second", TrimPromSuffixes("active_directory_ds_replication_object_rate_per_second", pmetric.MetricTypeGauge, "{objects}/s"))
-	require.Equal(t, "system_disk_operation_time_seconds", TrimPromSuffixes("system_disk_operation_time_seconds_total", pmetric.MetricTypeSum, "s"))
-}
-
-func TestNamespace(t *testing.T) {
-	require.Equal(t, "space_test", BuildPromCompliantName(createGauge("test", ""), "space"))
-	require.Equal(t, "space_test", BuildPromCompliantName(createGauge("#test", ""), "space"))
-}
-
-func TestCleanUpString(t *testing.T) {
-	require.Equal(t, "", CleanUpString(""))
-	require.Equal(t, "a_b", CleanUpString("a b"))
-	require.Equal(t, "hello_world", CleanUpString("hello, world!"))
-	require.Equal(t, "hello_you_2", CleanUpString("hello you 2"))
-	require.Equal(t, "1000", CleanUpString("$1000"))
-	require.Equal(t, "", CleanUpString("*+$^=)"))
-}
-
-func TestUnitMapGetOrDefault(t *testing.T) {
-	require.Equal(t, "", unitMapGetOrDefault(""))
-	require.Equal(t, "seconds", unitMapGetOrDefault("s"))
-	require.Equal(t, "invalid", unitMapGetOrDefault("invalid"))
-}
-
-func TestPerUnitMapGetOrDefault(t *testing.T) {
-	require.Equal(t, "", perUnitMapGetOrDefault(""))
-	require.Equal(t, "second", perUnitMapGetOrDefault("s"))
-	require.Equal(t, "invalid", perUnitMapGetOrDefault("invalid"))
-}
-
-func TestRemoveItem(t *testing.T) {
-	require.Equal(t, []string{}, removeItem([]string{}, "test"))
-	require.Equal(t, []string{}, removeItem([]string{}, ""))
-	require.Equal(t, []string{"a", "b", "c"}, removeItem([]string{"a", "b", "c"}, "d"))
-	require.Equal(t, []string{"a", "b", "c"}, removeItem([]string{"a", "b", "c"}, ""))
-	require.Equal(t, []string{"a", "b"}, removeItem([]string{"a", "b", "c"}, "c"))
-	require.Equal(t, []string{"a", "c"}, removeItem([]string{"a", "b", "c"}, "b"))
-	require.Equal(t, []string{"b", "c"}, removeItem([]string{"a", "b", "c"}, "a"))
-}
-
-func TestBuildPromCompliantName(t *testing.T) {
-	require.Equal(t, "system_io_bytes_total", BuildPromCompliantName(createCounter("system.io", "By"), ""))
-	require.Equal(t, "system_network_io_bytes_total", BuildPromCompliantName(createCounter("network.io", "By"), "system"))
-	require.Equal(t, "_3_14_digits", BuildPromCompliantName(createGauge("3.14 digits", ""), ""))
-	require.Equal(t, "envoy_rule_engine_zlib_buf_error", BuildPromCompliantName(createGauge("envoy__rule_engine_zlib_buf_error", ""), ""))
-	require.Equal(t, "foo_bar", BuildPromCompliantName(createGauge(":foo::bar", ""), ""))
-	require.Equal(t, "foo_bar_total", BuildPromCompliantName(createCounter(":foo::bar", ""), ""))
-}

storage/remote/otlptranslator/prometheus/testutils_test.go

@@ -1,34 +0,0 @@
-// Copyright The OpenTelemetry Authors
-// SPDX-License-Identifier: Apache-2.0
-
-package normalize
-
-import (
-	"go.opentelemetry.io/collector/pdata/pmetric"
-)
-
-var ilm pmetric.ScopeMetrics
-
-func init() {
-	metrics := pmetric.NewMetrics()
-	resourceMetrics := metrics.ResourceMetrics().AppendEmpty()
-	ilm = resourceMetrics.ScopeMetrics().AppendEmpty()
-}
-
-// Returns a new Metric of type "Gauge" with specified name and unit.
-func createGauge(name, unit string) pmetric.Metric {
-	gauge := ilm.Metrics().AppendEmpty()
-	gauge.SetName(name)
-	gauge.SetUnit(unit)
-	gauge.SetEmptyGauge()
-	return gauge
-}
-
-// Returns a new Metric of type Monotonic Sum with specified name and unit.
-func createCounter(name, unit string) pmetric.Metric {
-	counter := ilm.Metrics().AppendEmpty()
-	counter.SetEmptySum().SetIsMonotonic(true)
-	counter.SetName(name)
-	counter.SetUnit(unit)
-	return counter
-}

storage/remote/otlptranslator/prometheus/unit_to_ucum.go

@@ -0,0 +1,90 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package prometheus // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus"
+
+import "strings"
+
+var wordToUCUM = map[string]string{
+
+	// Time
+	"days":         "d",
+	"hours":        "h",
+	"minutes":      "min",
+	"seconds":      "s",
+	"milliseconds": "ms",
+	"microseconds": "us",
+	"nanoseconds":  "ns",
+
+	// Bytes
+	"bytes":     "By",
+	"kibibytes": "KiBy",
+	"mebibytes": "MiBy",
+	"gibibytes": "GiBy",
+	"tibibytes": "TiBy",
+	"kilobytes": "KBy",
+	"megabytes": "MBy",
+	"gigabytes": "GBy",
+	"terabytes": "TBy",
+
+	// SI
+	"meters":  "m",
+	"volts":   "V",
+	"amperes": "A",
+	"joules":  "J",
+	"watts":   "W",
+	"grams":   "g",
+
+	// Misc
+	"celsius": "Cel",
+	"hertz":   "Hz",
+	"ratio":   "1",
+	"percent": "%",
+}
+
+// The map that translates the "per" unit
+// Example: per_second (singular) => /s
+var perWordToUCUM = map[string]string{
+	"second": "s",
+	"minute": "m",
+	"hour":   "h",
+	"day":    "d",
+	"week":   "w",
+	"month":  "mo",
+	"year":   "y",
+}
+
+// UnitWordToUCUM converts english unit words to UCUM units:
+// https://ucum.org/ucum#section-Alphabetic-Index-By-Symbol
+// It also handles rates, such as meters_per_second, by translating the first
+// word to UCUM, and the "per" word to UCUM. It joins them with a "/" between.
+func UnitWordToUCUM(unit string) string {
+	unitTokens := strings.SplitN(unit, "_per_", 2)
+	if len(unitTokens) == 0 {
+		return ""
+	}
+	ucumUnit := wordToUCUMOrDefault(unitTokens[0])
+	if len(unitTokens) > 1 && unitTokens[1] != "" {
+		ucumUnit += "/" + perWordToUCUMOrDefault(unitTokens[1])
+	}
+	return ucumUnit
+}
+
+// wordToUCUMOrDefault retrieves the Prometheus "basic" unit corresponding to
+// the specified "basic" unit. Returns the specified unit if not found in
+// wordToUCUM.
+func wordToUCUMOrDefault(unit string) string {
+	if promUnit, ok := wordToUCUM[unit]; ok {
+		return promUnit
+	}
+	return unit
+}
+
+// perWordToUCUMOrDefault retrieve the Prometheus "per" unit corresponding to
+// the specified "per" unit. Returns the specified unit if not found in perWordToUCUM.
+func perWordToUCUMOrDefault(perUnit string) string {
+	if promPerUnit, ok := perWordToUCUM[perUnit]; ok {
+		return promPerUnit
+	}
+	return perUnit
+}

storage/remote/otlptranslator/prometheusremotewrite/helper.go

@@ -71,8 +71,8 @@ func (a ByLabelName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
 // creates a new TimeSeries in the map if not found and returns the time series signature.
 // tsMap will be unmodified if either labels or sample is nil, but can still be modified if the exemplar is nil.
 func addSample(tsMap map[string]*prompb.TimeSeries, sample *prompb.Sample, labels []prompb.Label,
-	datatype string,
+	datatype string) string {
-) string {
+
 	if sample == nil || labels == nil || tsMap == nil {
 		return ""
 	}
@@ -132,7 +132,14 @@ func addExemplar(tsMap map[string]*prompb.TimeSeries, bucketBounds []bucketBound
 // the label slice should not contain duplicate label names; this method sorts the slice by label name before creating
 // the signature.
 func timeSeriesSignature(datatype string, labels *[]prompb.Label) string {
+	length := len(datatype)
+
+	for _, lb := range *labels {
+		length += 2 + len(lb.GetName()) + len(lb.GetValue())
+	}
+
 	b := strings.Builder{}
+	b.Grow(length)
 	b.WriteString(datatype)
 
 	sort.Sort(ByLabelName(*labels))
@@ -151,8 +158,22 @@ func timeSeriesSignature(datatype string, labels *[]prompb.Label) string {
 // Unpaired string value is ignored. String pairs overwrites OTLP labels if collision happens, and the overwrite is
 // logged. Resultant label names are sanitized.
 func createAttributes(resource pcommon.Resource, attributes pcommon.Map, externalLabels map[string]string, extras ...string) []prompb.Label {
+	serviceName, haveServiceName := resource.Attributes().Get(conventions.AttributeServiceName)
+	instance, haveInstanceID := resource.Attributes().Get(conventions.AttributeServiceInstanceID)
+
+	// Calculate the maximum possible number of labels we could return so we can preallocate l
+	maxLabelCount := attributes.Len() + len(externalLabels) + len(extras)/2
+
+	if haveServiceName {
+		maxLabelCount++
+	}
+
+	if haveInstanceID {
+		maxLabelCount++
+	}
+
 	// map ensures no duplicate label name
-	l := map[string]prompb.Label{}
+	l := make(map[string]string, maxLabelCount)
 
 	// Ensure attributes are sorted by key for consistent merging of keys which
 	// collide when sanitized.
@@ -164,35 +185,25 @@ func createAttributes(resource pcommon.Resource, attributes pcommon.Map, externa
 	sort.Stable(ByLabelName(labels))
 
 	for _, label := range labels {
-		finalKey := prometheustranslator.NormalizeLabel(label.Name)
+		var finalKey = prometheustranslator.NormalizeLabel(label.Name)
 		if existingLabel, alreadyExists := l[finalKey]; alreadyExists {
-			existingLabel.Value = existingLabel.Value + ";" + label.Value
+			l[finalKey] = existingLabel + ";" + label.Value
-			l[finalKey] = existingLabel
 		} else {
-			l[finalKey] = prompb.Label{
+			l[finalKey] = label.Value
-				Name:  finalKey,
-				Value: label.Value,
-			}
 		}
 	}
 
 	// Map service.name + service.namespace to job
-	if serviceName, ok := resource.Attributes().Get(conventions.AttributeServiceName); ok {
+	if haveServiceName {
 		val := serviceName.AsString()
 		if serviceNamespace, ok := resource.Attributes().Get(conventions.AttributeServiceNamespace); ok {
 			val = fmt.Sprintf("%s/%s", serviceNamespace.AsString(), val)
 		}
-		l[model.JobLabel] = prompb.Label{
+		l[model.JobLabel] = val
-			Name:  model.JobLabel,
-			Value: val,
-		}
 	}
 	// Map service.instance.id to instance
-	if instance, ok := resource.Attributes().Get(conventions.AttributeServiceInstanceID); ok {
+	if haveInstanceID {
-		l[model.InstanceLabel] = prompb.Label{
+		l[model.InstanceLabel] = instance.AsString()
-			Name:  model.InstanceLabel,
-			Value: instance.AsString(),
-		}
 	}
 	for key, value := range externalLabels {
 		// External labels have already been sanitized
@@ -200,10 +211,7 @@ func createAttributes(resource pcommon.Resource, attributes pcommon.Map, externa
 			// Skip external labels if they are overridden by metric attributes
 			continue
 		}
-		l[key] = prompb.Label{
+		l[key] = value
-			Name:  key,
-			Value: value,
-		}
 	}
 
 	for i := 0; i < len(extras); i += 2 {
@@ -219,15 +227,12 @@ func createAttributes(resource pcommon.Resource, attributes pcommon.Map, externa
 		if !(len(name) > 4 && name[:2] == "__" && name[len(name)-2:] == "__") {
 			name = prometheustranslator.NormalizeLabel(name)
 		}
-		l[name] = prompb.Label{
+		l[name] = extras[i+1]
-			Name:  name,
-			Value: extras[i+1],
-		}
 	}
 
 	s := make([]prompb.Label, 0, len(l))
-	for _, lb := range l {
+	for k, v := range l {
-		s = append(s, lb)
+		s = append(s, prompb.Label{Name: k, Value: v})
 	}
 
 	return s
@@ -236,6 +241,7 @@ func createAttributes(resource pcommon.Resource, attributes pcommon.Map, externa
 // isValidAggregationTemporality checks whether an OTel metric has a valid
 // aggregation temporality for conversion to a Prometheus metric.
 func isValidAggregationTemporality(metric pmetric.Metric) bool {
+	//exhaustive:enforce
 	switch metric.Type() {
 	case pmetric.MetricTypeGauge, pmetric.MetricTypeSummary:
 		return true
@@ -254,7 +260,22 @@ func isValidAggregationTemporality(metric pmetric.Metric) bool {
 func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon.Resource, metric pmetric.Metric, settings Settings, tsMap map[string]*prompb.TimeSeries) {
 	timestamp := convertTimeStamp(pt.Timestamp())
 	// sum, count, and buckets of the histogram should append suffix to baseName
-	baseName := prometheustranslator.BuildPromCompliantName(metric, settings.Namespace)
+	baseName := prometheustranslator.BuildCompliantName(metric, settings.Namespace, settings.AddMetricSuffixes)
+	baseLabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels)
+
+	createLabels := func(nameSuffix string, extras ...string) []prompb.Label {
+		extraLabelCount := len(extras) / 2
+		labels := make([]prompb.Label, len(baseLabels), len(baseLabels)+extraLabelCount+1) // +1 for name
+		copy(labels, baseLabels)
+
+		for extrasIdx := 0; extrasIdx < extraLabelCount; extrasIdx++ {
+			labels = append(labels, prompb.Label{Name: extras[extrasIdx], Value: extras[extrasIdx+1]})
+		}
+
+		labels = append(labels, prompb.Label{Name: nameStr, Value: baseName + nameSuffix})
+
+		return labels
+	}
 
 	// If the sum is unset, it indicates the _sum metric point should be
 	// omitted
@@ -268,7 +289,7 @@ func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon
 			sum.Value = math.Float64frombits(value.StaleNaN)
 		}
 
-		sumlabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+sumStr)
+		sumlabels := createLabels(sumStr)
 		addSample(tsMap, sum, sumlabels, metric.Type().String())
 
 	}
@@ -282,7 +303,7 @@ func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon
 		count.Value = math.Float64frombits(value.StaleNaN)
 	}
 
-	countlabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+countStr)
+	countlabels := createLabels(countStr)
 	addSample(tsMap, count, countlabels, metric.Type().String())
 
 	// cumulative count for conversion to cumulative histogram
@@ -304,7 +325,7 @@ func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon
 			bucket.Value = math.Float64frombits(value.StaleNaN)
 		}
 		boundStr := strconv.FormatFloat(bound, 'f', -1, 64)
-		labels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+bucketStr, leStr, boundStr)
+		labels := createLabels(bucketStr, leStr, boundStr)
 		sig := addSample(tsMap, bucket, labels, metric.Type().String())
 
 		bucketBounds = append(bucketBounds, bucketBoundsData{sig: sig, bound: bound})
@@ -318,7 +339,7 @@ func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon
 	} else {
 		infBucket.Value = float64(pt.Count())
 	}
-	infLabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+bucketStr, leStr, pInfStr)
+	infLabels := createLabels(bucketStr, leStr, pInfStr)
 	sig := addSample(tsMap, infBucket, infLabels, metric.Type().String())
 
 	bucketBounds = append(bucketBounds, bucketBoundsData{sig: sig, bound: math.Inf(1)})
@@ -327,14 +348,8 @@ func addSingleHistogramDataPoint(pt pmetric.HistogramDataPoint, resource pcommon
 	// add _created time series if needed
 	startTimestamp := pt.StartTimestamp()
 	if settings.ExportCreatedMetric && startTimestamp != 0 {
-		createdLabels := createAttributes(
+		labels := createLabels(createdSuffix)
-			resource,
+		addCreatedTimeSeriesIfNeeded(tsMap, labels, startTimestamp, metric.Type().String())
-			pt.Attributes(),
-			settings.ExternalLabels,
-			nameStr,
-			baseName+createdSuffix,
-		)
-		addCreatedTimeSeriesIfNeeded(tsMap, createdLabels, startTimestamp, metric.Type().String())
 	}
 }
 
@@ -402,6 +417,7 @@ func getPromExemplars[T exemplarType](pt T) []prompb.Exemplar {
 func mostRecentTimestampInMetric(metric pmetric.Metric) pcommon.Timestamp {
 	var ts pcommon.Timestamp
 	// handle individual metric based on type
+	//exhaustive:enforce
 	switch metric.Type() {
 	case pmetric.MetricTypeGauge:
 		dataPoints := metric.Gauge().DataPoints()
@@ -441,11 +457,26 @@ func maxTimestamp(a, b pcommon.Timestamp) pcommon.Timestamp {
 
 // addSingleSummaryDataPoint converts pt to len(QuantileValues) + 2 samples.
 func addSingleSummaryDataPoint(pt pmetric.SummaryDataPoint, resource pcommon.Resource, metric pmetric.Metric, settings Settings,
-	tsMap map[string]*prompb.TimeSeries,
+	tsMap map[string]*prompb.TimeSeries) {
-) {
 	timestamp := convertTimeStamp(pt.Timestamp())
 	// sum and count of the summary should append suffix to baseName
-	baseName := prometheustranslator.BuildPromCompliantName(metric, settings.Namespace)
+	baseName := prometheustranslator.BuildCompliantName(metric, settings.Namespace, settings.AddMetricSuffixes)
+	baseLabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels)
+
+	createLabels := func(name string, extras ...string) []prompb.Label {
+		extraLabelCount := len(extras) / 2
+		labels := make([]prompb.Label, len(baseLabels), len(baseLabels)+extraLabelCount+1) // +1 for name
+		copy(labels, baseLabels)
+
+		for extrasIdx := 0; extrasIdx < extraLabelCount; extrasIdx++ {
+			labels = append(labels, prompb.Label{Name: extras[extrasIdx], Value: extras[extrasIdx+1]})
+		}
+
+		labels = append(labels, prompb.Label{Name: nameStr, Value: name})
+
+		return labels
+	}
+
 	// treat sum as a sample in an individual TimeSeries
 	sum := &prompb.Sample{
 		Value:     pt.Sum(),
@@ -454,7 +485,7 @@ func addSingleSummaryDataPoint(pt pmetric.SummaryDataPoint, resource pcommon.Res
 	if pt.Flags().NoRecordedValue() {
 		sum.Value = math.Float64frombits(value.StaleNaN)
 	}
-	sumlabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+sumStr)
+	sumlabels := createLabels(baseName + sumStr)
 	addSample(tsMap, sum, sumlabels, metric.Type().String())
 
 	// treat count as a sample in an individual TimeSeries
@@ -465,7 +496,7 @@ func addSingleSummaryDataPoint(pt pmetric.SummaryDataPoint, resource pcommon.Res
 	if pt.Flags().NoRecordedValue() {
 		count.Value = math.Float64frombits(value.StaleNaN)
 	}
-	countlabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName+countStr)
+	countlabels := createLabels(baseName + countStr)
 	addSample(tsMap, count, countlabels, metric.Type().String())
 
 	// process each percentile/quantile
@@ -479,20 +510,14 @@ func addSingleSummaryDataPoint(pt pmetric.SummaryDataPoint, resource pcommon.Res
 			quantile.Value = math.Float64frombits(value.StaleNaN)
 		}
 		percentileStr := strconv.FormatFloat(qt.Quantile(), 'f', -1, 64)
-		qtlabels := createAttributes(resource, pt.Attributes(), settings.ExternalLabels, nameStr, baseName, quantileStr, percentileStr)
+		qtlabels := createLabels(baseName, quantileStr, percentileStr)
 		addSample(tsMap, quantile, qtlabels, metric.Type().String())
 	}
 
 	// add _created time series if needed
 	startTimestamp := pt.StartTimestamp()
 	if settings.ExportCreatedMetric && startTimestamp != 0 {
-		createdLabels := createAttributes(
+		createdLabels := createLabels(baseName + createdSuffix)
-			resource,
-			pt.Attributes(),
-			settings.ExternalLabels,
-			nameStr,
-			baseName+createdSuffix,
-		)
 		addCreatedTimeSeriesIfNeeded(tsMap, createdLabels, startTimestamp, metric.Type().String())
 	}
 }

storage/remote/otlptranslator/prometheusremotewrite/histograms.go

@@ -60,15 +60,20 @@ func addSingleExponentialHistogramDataPoint(
 // to Prometheus Native Histogram.
 func exponentialToNativeHistogram(p pmetric.ExponentialHistogramDataPoint) (prompb.Histogram, error) {
 	scale := p.Scale()
-	if scale < -4 || scale > 8 {
+	if scale < -4 {
 		return prompb.Histogram{},
 			fmt.Errorf("cannot convert exponential to native histogram."+
-				" Scale must be <= 8 and >= -4, was %d", scale)
+				" Scale must be >= -4, was %d", scale)
-		// TODO: downscale to 8 if scale > 8
 	}
 
-	pSpans, pDeltas := convertBucketsLayout(p.Positive())
+	var scaleDown int32
-	nSpans, nDeltas := convertBucketsLayout(p.Negative())
+	if scale > 8 {
+		scaleDown = scale - 8
+		scale = 8
+	}
+
+	pSpans, pDeltas := convertBucketsLayout(p.Positive(), scaleDown)
+	nSpans, nDeltas := convertBucketsLayout(p.Negative(), scaleDown)
 
 	h := prompb.Histogram{
 		Schema: scale,
@@ -106,17 +111,19 @@ func exponentialToNativeHistogram(p pmetric.ExponentialHistogramDataPoint) (prom
 // The bucket indexes conversion was adjusted, since OTel exp. histogram bucket
 // index 0 corresponds to the range (1, base] while Prometheus bucket index 0
 // to the range (base 1].
-func convertBucketsLayout(buckets pmetric.ExponentialHistogramDataPointBuckets) ([]prompb.BucketSpan, []int64) {
+//
+// scaleDown is the factor by which the buckets are scaled down. In other words 2^scaleDown buckets will be merged into one.
+func convertBucketsLayout(buckets pmetric.ExponentialHistogramDataPointBuckets, scaleDown int32) ([]prompb.BucketSpan, []int64) {
 	bucketCounts := buckets.BucketCounts()
 	if bucketCounts.Len() == 0 {
 		return nil, nil
 	}
 
 	var (
-		spans         []prompb.BucketSpan
+		spans     []prompb.BucketSpan
-		deltas        []int64
+		deltas    []int64
-		prevCount     int64
+		count     int64
-		nextBucketIdx int32
+		prevCount int64
 	)
 
 	appendDelta := func(count int64) {
@@ -125,34 +132,67 @@ func convertBucketsLayout(buckets pmetric.ExponentialHistogramDataPointBuckets)
 		prevCount = count
 	}
 
-	for i := 0; i < bucketCounts.Len(); i++ {
+	// Let the compiler figure out that this is const during this function by
-		count := int64(bucketCounts.At(i))
+	// moving it into a local variable.
+	numBuckets := bucketCounts.Len()
+
+	// The offset is scaled and adjusted by 1 as described above.
+	bucketIdx := buckets.Offset()>>scaleDown + 1
+	spans = append(spans, prompb.BucketSpan{
+		Offset: bucketIdx,
+		Length: 0,
+	})
+
+	for i := 0; i < numBuckets; i++ {
+		// The offset is scaled and adjusted by 1 as described above.
+		nextBucketIdx := (int32(i)+buckets.Offset())>>scaleDown + 1
+		if bucketIdx == nextBucketIdx { // We have not collected enough buckets to merge yet.
+			count += int64(bucketCounts.At(i))
+			continue
+		}
 		if count == 0 {
+			count = int64(bucketCounts.At(i))
 			continue
 		}
 
-		// The offset is adjusted by 1 as described above.
+		gap := nextBucketIdx - bucketIdx - 1
-		bucketIdx := int32(i) + buckets.Offset() + 1
+		if gap > 2 {
-		delta := bucketIdx - nextBucketIdx
+			// We have to create a new span, because we have found a gap
-		if i == 0 || delta > 2 {
-			// We have to create a new span, either because we are
-			// at the very beginning, or because we have found a gap
 			// of more than two buckets. The constant 2 is copied from the logic in
 			// https://github.com/prometheus/client_golang/blob/27f0506d6ebbb117b6b697d0552ee5be2502c5f2/prometheus/histogram.go#L1296
 			spans = append(spans, prompb.BucketSpan{
-				Offset: delta,
+				Offset: gap,
 				Length: 0,
 			})
 		} else {
 			// We have found a small gap (or no gap at all).
 			// Insert empty buckets as needed.
-			for j := int32(0); j < delta; j++ {
+			for j := int32(0); j < gap; j++ {
 				appendDelta(0)
 			}
 		}
 		appendDelta(count)
-		nextBucketIdx = bucketIdx + 1
+		count = int64(bucketCounts.At(i))
+		bucketIdx = nextBucketIdx
 	}
+	// Need to use the last item's index. The offset is scaled and adjusted by 1 as described above.
+	gap := (int32(numBuckets)+buckets.Offset()-1)>>scaleDown + 1 - bucketIdx
+	if gap > 2 {
+		// We have to create a new span, because we have found a gap
+		// of more than two buckets. The constant 2 is copied from the logic in
+		// https://github.com/prometheus/client_golang/blob/27f0506d6ebbb117b6b697d0552ee5be2502c5f2/prometheus/histogram.go#L1296
+		spans = append(spans, prompb.BucketSpan{
+			Offset: gap,
+			Length: 0,
+		})
+	} else {
+		// We have found a small gap (or no gap at all).
+		// Insert empty buckets as needed.
+		for j := int32(0); j < gap; j++ {
+			appendDelta(0)
+		}
+	}
+	appendDelta(count)
 
 	return spans, deltas
 }

storage/remote/otlptranslator/prometheusremotewrite/metrics_to_prw.go

@@ -22,6 +22,7 @@ type Settings struct {
 	ExternalLabels      map[string]string
 	DisableTargetInfo   bool
 	ExportCreatedMetric bool
+	AddMetricSuffixes   bool
 }
 
 // FromMetrics converts pmetric.Metrics to prometheus remote write format.
@@ -51,6 +52,7 @@ func FromMetrics(md pmetric.Metrics, settings Settings) (tsMap map[string]*promp
 				}
 
 				// handle individual metric based on type
+				//exhaustive:enforce
 				switch metric.Type() {
 				case pmetric.MetricTypeGauge:
 					dataPoints := metric.Gauge().DataPoints()
@@ -81,7 +83,7 @@ func FromMetrics(md pmetric.Metrics, settings Settings) (tsMap map[string]*promp
 					if dataPoints.Len() == 0 {
 						errs = multierr.Append(errs, fmt.Errorf("empty data points. %s is dropped", metric.Name()))
 					}
-					name := prometheustranslator.BuildPromCompliantName(metric, settings.Namespace)
+					name := prometheustranslator.BuildCompliantName(metric, settings.Namespace, settings.AddMetricSuffixes)
 					for x := 0; x < dataPoints.Len(); x++ {
 						errs = multierr.Append(
 							errs,

storage/remote/otlptranslator/prometheusremotewrite/number_data_points.go

@@ -27,7 +27,7 @@ func addSingleGaugeNumberDataPoint(
 	settings Settings,
 	series map[string]*prompb.TimeSeries,
 ) {
-	name := prometheustranslator.BuildPromCompliantName(metric, settings.Namespace)
+	name := prometheustranslator.BuildCompliantName(metric, settings.Namespace, settings.AddMetricSuffixes)
 	labels := createAttributes(
 		resource,
 		pt.Attributes(),
@@ -60,7 +60,7 @@ func addSingleSumNumberDataPoint(
 	settings Settings,
 	series map[string]*prompb.TimeSeries,
 ) {
-	name := prometheustranslator.BuildPromCompliantName(metric, settings.Namespace)
+	name := prometheustranslator.BuildCompliantName(metric, settings.Namespace, settings.AddMetricSuffixes)
 	labels := createAttributes(
 		resource,
 		pt.Attributes(),

storage/remote/otlptranslator/update-copy.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-OTEL_VERSION=v0.81.0
+OTEL_VERSION=v0.88.0
 
 git clone https://github.com/open-telemetry/opentelemetry-collector-contrib ./tmp
 cd ./tmp
@@ -8,7 +8,8 @@ git checkout $OTEL_VERSION
 cd ..
 rm -rf ./prometheusremotewrite/*
 cp -r ./tmp/pkg/translator/prometheusremotewrite/*.go ./prometheusremotewrite
-rm -rf ./prometheusremotewrite/*_test.go
+cp -r ./tmp/pkg/translator/prometheus/*.go ./prometheus
+rm -rf ./prometheus/*_test.go
 rm -rf ./tmp
 
 sed -i '' 's#github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/prometheus#github.com/prometheus/prometheus/storage/remote/otlptranslator/prometheus#g' ./prometheusremotewrite/*.go