Loki: backend: use json-field (#48486)

* fixed strings

* loki: backend: use json-field

pkg/tsdb/loki/frame.go

@@ -1,6 +1,7 @@
 package loki
 
 import (
+	"encoding/json"
 	"fmt"
 	"hash/fnv"
 	"sort"
@@ -88,12 +89,12 @@ func adjustLogsFrame(frame *data.Frame, query *lokiQuery) error {
 	timeField := fields[1]
 	lineField := fields[2]
 
-	if (timeField.Type() != data.FieldTypeTime) || (lineField.Type() != data.FieldTypeString) || (labelsField.Type() != data.FieldTypeString) {
-		return fmt.Errorf("invalid fields in metric frame")
+	if (timeField.Type() != data.FieldTypeTime) || (lineField.Type() != data.FieldTypeString) || (labelsField.Type() != data.FieldTypeJSON) {
+		return fmt.Errorf("invalid fields in logs frame")
 	}
 
 	if (timeField.Len() != lineField.Len()) || (timeField.Len() != labelsField.Len()) {
-		return fmt.Errorf("invalid fields in metric frame")
+		return fmt.Errorf("invalid fields in logs frame")
 	}
 
 	if frame.Meta == nil {
@@ -127,8 +128,9 @@ func makeStringTimeField(timeField *data.Field) *data.Field {
 	return data.NewField("tsNs", timeField.Labels.Copy(), stringTimestamps)
 }
 
-func calculateCheckSum(time string, line string, labels string) (string, error) {
-	input := []byte(line + "_" + labels)
+func calculateCheckSum(time string, line string, labels []byte) (string, error) {
+	input := []byte(line + "_")
+	input = append(input, labels...)
 	hash := fnv.New32()
 	_, err := hash.Write(input)
 	if err != nil {
@@ -147,7 +149,7 @@ func makeIdField(stringTimeField *data.Field, lineField *data.Field, labelsField
 	for i := 0; i < length; i++ {
 		time := stringTimeField.At(i).(string)
 		line := lineField.At(i).(string)
-		labels := labelsField.At(i).(string)
+		labels := labelsField.At(i).(json.RawMessage)
 
 		sum, err := calculateCheckSum(time, line, labels)
 		if err != nil {

pkg/tsdb/loki/frame_test.go

@@ -1,6 +1,7 @@
 package loki
 
 import (
+	"encoding/json"
 	"testing"
 	"time"
 
@@ -39,11 +40,11 @@ func TestFormatName(t *testing.T) {
 func TestAdjustFrame(t *testing.T) {
 	t.Run("logs-frame metadata should be set correctly", func(t *testing.T) {
 		frame := data.NewFrame("",
-			data.NewField("labels", nil, []string{
-				`{"level":"info"}`,
-				`{"level":"error"}`,
-				`{"level":"error"}`,
-				`{"level":"info"}`,
+			data.NewField("labels", nil, []json.RawMessage{
+				json.RawMessage(`{"level":"info"}`),
+				json.RawMessage(`{"level":"error"}`),
+				json.RawMessage(`{"level":"error"}`),
+				json.RawMessage(`{"level":"info"}`),
 			}),
 			data.NewField("time", nil, []time.Time{
 				time.Date(2022, 1, 2, 3, 4, 5, 6, time.UTC),
@@ -86,7 +87,7 @@ func TestAdjustFrame(t *testing.T) {
 		require.Equal(t, "1641092765000000006_948c1a7d_A", idField.At(3))
 	})
 
-	t.Run("logs-frame id and string-time fields should be created", func(t *testing.T) {
+	t.Run("naming inside metric fields should be correct", func(t *testing.T) {
 		field1 := data.NewField("", nil, make([]time.Time, 0))
 		field2 := data.NewField("", nil, make([]float64, 0))
 		field2.Labels = data.Labels{"app": "Application", "tag2": "tag2"}

pkg/tsdb/loki/parse_response.go

@@ -1,8 +1,8 @@
 package loki
 
 import (
+	"encoding/json"
 	"fmt"
-	"sort"
 	"time"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
@@ -109,35 +109,23 @@ func lokiVectorToDataFrames(vector loghttp.Vector, query *lokiQuery, stats []dat
 }
 
 // we serialize the labels as an ordered list of pairs
-func labelsToString(labels data.Labels) (string, error) {
-	keys := make([]string, 0, len(labels))
-	for k := range labels {
-		keys = append(keys, k)
-	}
-	sort.Strings(keys)
-
-	labelArray := make([][2]string, 0, len(labels))
-
-	for _, k := range keys {
-		pair := [2]string{k, labels[k]}
-		labelArray = append(labelArray, pair)
-	}
-
-	bytes, err := jsoniter.Marshal(labelArray)
+func labelsToRawJson(labels data.Labels) (json.RawMessage, error) {
+	// data.Labels when converted to JSON keep the fields sorted
+	bytes, err := jsoniter.Marshal(labels)
 	if err != nil {
-		return "", err
+		return nil, err
 	}
 
-	return string(bytes), nil
+	return json.RawMessage(bytes), nil
 }
 
 func lokiStreamsToDataFrames(streams loghttp.Streams, query *lokiQuery, stats []data.QueryStat) (data.Frames, error) {
 	var timeVector []time.Time
 	var values []string
-	var labelsVector []string
+	var labelsVector []json.RawMessage
 
 	for _, v := range streams {
-		labelsText, err := labelsToString(v.Labels.Map())
+		labelsJson, err := labelsToRawJson(v.Labels.Map())
 		if err != nil {
 			return nil, err
 		}
@@ -145,17 +133,13 @@ func lokiStreamsToDataFrames(streams loghttp.Streams, query *lokiQuery, stats []
 		for _, k := range v.Entries {
 			timeVector = append(timeVector, k.Timestamp.UTC())
 			values = append(values, k.Line)
-			labelsVector = append(labelsVector, labelsText)
+			labelsVector = append(labelsVector, labelsJson)
 		}
 	}
 
 	timeField := data.NewField(data.TimeSeriesTimeFieldName, nil, timeVector)
 	valueField := data.NewField("Line", nil, values)
 	labelsField := data.NewField("labels", nil, labelsVector)
-	labelsField.Config = &data.FieldConfig{
-		// we should have a native json-field-type
-		Custom: map[string]interface{}{"json": true},
-	}
 
 	frame := data.NewFrame("", labelsField, timeField, valueField)
 	frame.SetMeta(&data.FrameMeta{