model/labels: Add Label.Identifying field

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

model/labels/labels.go

@@ -412,8 +412,12 @@ func (b *ScratchBuilder) Reset() {
 
 // Add a name/value pair.
 // Note if you Add the same name twice you will get a duplicate label, which is invalid.
-func (b *ScratchBuilder) Add(name, value string) {
-	b.add = append(b.add, Label{Name: name, Value: value})
+func (b *ScratchBuilder) Add(name, value string, identifyingLabels ...string) {
+	identifying := false
+	if len(identifyingLabels) > 0 && slices.Contains(identifyingLabels, name) {
+		identifying = true
+	}
+	b.add = append(b.add, Label{Name: name, Value: value, Identifying: identifying})
 }
 
 // Add a name/value pair, using []byte instead of string.

model/labels/labels_common.go

@@ -16,6 +16,7 @@ package labels
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"strconv"
 
 	"github.com/prometheus/common/model"
@@ -36,6 +37,13 @@ var seps = []byte{'\xff'}
 // Label is a key/value pair of strings.
 type Label struct {
 	Name, Value string
+	// Identifying signifies whether this is an identifying label for an info metric.
+	Identifying bool
+}
+
+// String returns l's string representation.
+func (l Label) String() string {
+	return fmt.Sprintf("%s=%s", l.Name, l.Value)
 }
 
 func (ls Labels) String() string {

model/labels/labels_stringlabels.go

@@ -620,8 +620,12 @@ func (b *ScratchBuilder) Reset() {
 
 // Add a name/value pair.
 // Note if you Add the same name twice you will get a duplicate label, which is invalid.
-func (b *ScratchBuilder) Add(name, value string) {
-	b.add = append(b.add, Label{Name: name, Value: value})
+func (b *ScratchBuilder) Add(name, value string, identifyingLabels ...string) {
+	identifying := false
+	if len(identifyingLabels) > 0 && slices.Contains(identifyingLabels, name) {
+		identifying = true
+	}
+	b.add = append(b.add, Label{Name: name, Value: value, Identifying: identifying})
 }
 
 // Add a name/value pair, using []byte instead of string to reduce memory allocations.

model/labels/labels_test.go

@@ -582,7 +582,7 @@ func TestBuilder(t *testing.T) {
 		},
 		{
 			base: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
-			set:  []Label{{"aaa", "444"}, {"bbb", "555"}, {"ccc", "666"}},
+			set:  []Label{{Name: "aaa", Value: "444"}, {Name: "bbb", Value: "555"}, {Name: "ccc", Value: "666"}},
 			want: FromStrings("aaa", "444", "bbb", "555", "ccc", "666"),
 		},
 		{
@@ -591,24 +591,24 @@ func TestBuilder(t *testing.T) {
 			want: FromStrings("aaa", "111", "ccc", "333"),
 		},
 		{
-			set:  []Label{{"aaa", "111"}, {"bbb", "222"}, {"ccc", "333"}},
+			set:  []Label{{Name: "aaa", Value: "111"}, {Name: "bbb", Value: "222"}, {Name: "ccc", Value: "333"}},
 			del:  []string{"bbb"},
 			want: FromStrings("aaa", "111", "ccc", "333"),
 		},
 		{
 			base: FromStrings("aaa", "111"),
-			set:  []Label{{"bbb", "222"}},
+			set:  []Label{{Name: "bbb", Value: "222"}},
 			want: FromStrings("aaa", "111", "bbb", "222"),
 		},
 		{
 			base: FromStrings("aaa", "111"),
-			set:  []Label{{"bbb", "222"}, {"bbb", "333"}},
+			set:  []Label{{Name: "bbb", Value: "222"}, {Name: "bbb", Value: "333"}},
 			want: FromStrings("aaa", "111", "bbb", "333"),
 		},
 		{
 			base: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
 			del:  []string{"bbb"},
-			set:  []Label{{"ddd", "444"}},
+			set:  []Label{{Name: "ddd", Value: "444"}},
 			want: FromStrings("aaa", "111", "ccc", "333", "ddd", "444"),
 		},
 		{ // Blank value is interpreted as delete.
@@ -617,7 +617,7 @@ func TestBuilder(t *testing.T) {
 		},
 		{
 			base: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
-			set:  []Label{{"bbb", ""}},
+			set:  []Label{{Name: "bbb", Value: ""}},
 			want: FromStrings("aaa", "111", "ccc", "333"),
 		},
 		{
@@ -633,7 +633,7 @@ func TestBuilder(t *testing.T) {
 		{
 			base: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
 			del:  []string{"bbb"},
-			set:  []Label{{"ddd", "444"}},
+			set:  []Label{{Name: "ddd", Value: "444"}},
 			keep: []string{"aaa", "ddd"},
 			want: FromStrings("aaa", "111", "ddd", "444"),
 		},
@@ -677,19 +677,19 @@ func TestScratchBuilder(t *testing.T) {
 			want: EmptyLabels(),
 		},
 		{
-			add:  []Label{{"aaa", "111"}},
+			add:  []Label{{Name: "aaa", Value: "111"}},
 			want: FromStrings("aaa", "111"),
 		},
 		{
-			add:  []Label{{"aaa", "111"}, {"bbb", "222"}, {"ccc", "333"}},
+			add:  []Label{{Name: "aaa", Value: "111"}, {Name: "bbb", Value: "222"}, {Name: "ccc", Value: "333"}},
 			want: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
 		},
 		{
-			add:  []Label{{"bbb", "222"}, {"aaa", "111"}, {"ccc", "333"}},
+			add:  []Label{{Name: "bbb", Value: "222"}, {Name: "aaa", Value: "111"}, {Name: "ccc", Value: "333"}},
 			want: FromStrings("aaa", "111", "bbb", "222", "ccc", "333"),
 		},
 		{
-			add:  []Label{{"ddd", "444"}},
+			add:  []Label{{Name: "ddd", Value: "444"}},
 			want: FromStrings("ddd", "444"),
 		},
 	} {
@@ -769,15 +769,15 @@ func BenchmarkLabels_Hash(b *testing.B) {
 
 func BenchmarkBuilder(b *testing.B) {
 	m := []Label{
-		{"job", "node"},
-		{"instance", "123.123.1.211:9090"},
-		{"path", "/api/v1/namespaces/<namespace>/deployments/<name>"},
-		{"method", "GET"},
-		{"namespace", "system"},
-		{"status", "500"},
-		{"prometheus", "prometheus-core-1"},
-		{"datacenter", "eu-west-1"},
-		{"pod_name", "abcdef-99999-defee"},
+		{Name: "job", Value: "node"},
+		{Name: "instance", Value: "123.123.1.211:9090"},
+		{Name: "path", Value: "/api/v1/namespaces/<namespace>/deployments/<name>"},
+		{Name: "method", Value: "GET"},
+		{Name: "namespace", Value: "system"},
+		{Name: "status", Value: "500"},
+		{Name: "prometheus", Value: "prometheus-core-1"},
+		{Name: "datacenter", Value: "eu-west-1"},
+		{Name: "pod_name", Value: "abcdef-99999-defee"},
 	}
 
 	var l Labels

storage/remote/codec.go

@@ -760,10 +760,10 @@ func LabelProtosToMetric(labelPairs []*prompb.Label) model.Metric {
 	return metric
 }
 
-func labelProtosToLabels(labelPairs []prompb.Label) labels.Labels {
+func labelProtosToLabels(labelPairs []prompb.Label, identifyingLabels ...string) labels.Labels {
 	b := labels.ScratchBuilder{}
 	for _, l := range labelPairs {
-		b.Add(l.Name, l.Value)
+		b.Add(l.Name, l.Value, identifyingLabels...)
 	}
 	b.Sort()
 	return b.Labels()

storage/remote/otlptranslator/prometheusremotewrite/helper.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"log"
 	"math"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -86,9 +87,10 @@ func addSample(tsMap map[string]*prompb.TimeSeries, sample *prompb.Sample, label
 		var identifyingLabels []string
 		if isTargetMetric {
 			identifyingLabels = []string{
-				model.JobLabel,
 				model.InstanceLabel,
+				model.JobLabel,
 			}
+			slices.Sort(identifyingLabels)
 		}
 		newTs := &prompb.TimeSeries{
 			Labels:            labels,

storage/remote/write_handler.go

@@ -114,14 +114,16 @@ func (h *writeHandler) write(ctx context.Context, req *prompb.WriteRequest) (err
 
 	var exemplarErr error
 	for _, ts := range req.Timeseries {
-		labels := labelProtosToLabels(ts.Labels)
+		labels := labelProtosToLabels(ts.Labels, ts.IdentifyingLabels...)
 		if !labels.IsValid() {
 			level.Warn(h.logger).Log("msg", "Invalid metric names or labels", "got", labels.String())
 			samplesWithInvalidLabels++
 			continue
 		}
 		var ref storage.SeriesRef
 		for _, s := range ts.Samples {
+			// When recording a sample for an info type metric with identifying labels,
+			// make sure also to persist which of the labels are identifying
 			ref, err = app.Append(ref, labels, s.Timestamp, s.Value)
 			if err != nil {
 				unwrappedErr := errors.Unwrap(err)
@@ -225,7 +227,6 @@ func (h *otlpWriteHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 
 	prwMetrics := make([]prompb.TimeSeries, 0, len(prwMetricsMap))
-
 	for _, ts := range prwMetricsMap {
 		prwMetrics = append(prwMetrics, *ts)
 	}