Merge pull request #406 from alibresco/main

Sort prometheus labels in accordance with the prometheus spec

pkg/outputs/prometheus_output/prometheus_common.go

@@ -9,10 +9,12 @@
 package prometheus_output
 
 import (
+	"cmp"
 	"errors"
 	"math"
 	"path/filepath"
 	"regexp"
+	"slices"
 	"strconv"
 	"strings"
 	"time"
@@ -152,6 +154,13 @@ func (m *MetricBuilder) TimeSeriesFromEvent(ev *formatters.EventMsg) []*NamedTim
 				Name:  labels.MetricName,
 				Value: tsName,
 			})
+
+		// The prometheus spec requires label names to be sorted
+		// https://prometheus.io/docs/concepts/remote_write_spec/
+		slices.SortFunc(tsLabelsWithName, func(a prompb.Label, b prompb.Label) int {
+			return cmp.Compare(a.Name, b.Name)
+		})
+
 		nts := &NamedTimeSeries{
 			Name: tsName,
 			TS: &prompb.TimeSeries{

pkg/outputs/prometheus_output/prometheus_common_test.go

@@ -9,10 +9,13 @@
 package prometheus_output
 
 import (
+	"cmp"
+	"slices"
 	"testing"
 
 	"github.com/openconfig/gnmic/pkg/formatters"
 	"github.com/prometheus/prometheus/model/labels"
+	"github.com/prometheus/prometheus/prompb"
 )
 
 var metricNameSet = map[string]struct {
@@ -97,6 +100,32 @@ func TestTimeSeriesFromEvent(t *testing.T) {
 	}
 }
 
+func TestTimeSeriesLabelsSorted(t *testing.T) {
+	metricBuilder := &MetricBuilder{StringsAsLabels: true}
+	event := &formatters.EventMsg{
+		Name:      "eventName",
+		Timestamp: 12345,
+		Tags: map[string]string{
+			"tagName": "tagVal",
+		},
+		Values: map[string]interface{}{
+			"strName1": "strVal1",
+			"strName2": "strVal2",
+			"intName1": 1,
+			"intName2": 2,
+		},
+		Deletes: []string{},
+	}
+	for _, nts := range metricBuilder.TimeSeriesFromEvent(event) {
+		areLabelsSorted := slices.IsSortedFunc(nts.TS.Labels, func(a prompb.Label, b prompb.Label) int {
+			return cmp.Compare(a.Name, b.Name)
+		})
+		if !areLabelsSorted {
+			t.Errorf("labels names are not sorted, got '%v'", nts.TS.Labels)
+		}
+	}
+}
+
 func TestMetricName(t *testing.T) {
 	for name, tc := range metricNameSet {
 		t.Run(name, func(t *testing.T) {