Prometheus: Various buffered and streaming parsing fixes (#55941)

pkg/tsdb/prometheus/querydata/framing_test.go

@@ -32,13 +32,14 @@ func TestMatrixResponses(t *testing.T) {
 		{name: "parse a simple matrix response with value missing steps", filepath: "range_missing"},
 		{name: "parse a response with Infinity", filepath: "range_infinity"},
 		{name: "parse a response with NaN", filepath: "range_nan"},
+		{name: "parse a response with legendFormat __auto", filepath: "range_auto"},
 	}
 
 	for _, test := range tt {
 		enableWideSeries := false
 		queryFileName := filepath.Join("../testdata", test.filepath+".query.json")
 		responseFileName := filepath.Join("../testdata", test.filepath+".result.json")
-		goldenFileName := test.filepath + ".result.streaming.golden"
+		goldenFileName := test.filepath + ".result.golden"
 		t.Run(test.name, goldenScenario(test.name, queryFileName, responseFileName, goldenFileName, enableWideSeries))
 		enableWideSeries = true
 		goldenFileName = test.filepath + ".result.streaming-wide.golden"
@@ -71,12 +72,13 @@ func goldenScenario(name, queryFileName, responseFileName, goldenFileName string
 // struct here, because it has `time.time` and `time.duration` fields that
 // cannot be unmarshalled from JSON automatically.
 type storedPrometheusQuery struct {
-	RefId      string
-	RangeQuery bool
-	Start      int64
-	End        int64
-	Step       int64
-	Expr       string
+	RefId        string
+	RangeQuery   bool
+	Start        int64
+	End          int64
+	Step         int64
+	Expr         string
+	LegendFormat string
 }
 
 func loadStoredQuery(fileName string) (*backend.QueryDataRequest, error) {
@@ -94,10 +96,11 @@ func loadStoredQuery(fileName string) (*backend.QueryDataRequest, error) {
 	}
 
 	qm := models.QueryModel{
-		RangeQuery: sq.RangeQuery,
-		Expr:       sq.Expr,
-		Interval:   fmt.Sprintf("%ds", sq.Step),
-		IntervalMS: sq.Step * 1000,
+		RangeQuery:   sq.RangeQuery,
+		Expr:         sq.Expr,
+		Interval:     fmt.Sprintf("%ds", sq.Step),
+		IntervalMS:   sq.Step * 1000,
+		LegendFormat: sq.LegendFormat,
 	}
 
 	data, err := json.Marshal(&qm)

pkg/tsdb/prometheus/querydata/response.go

@@ -108,11 +108,11 @@ func getName(q *models.Query, field *data.Field) string {
 	labels := field.Labels
 	legend := metricNameFromLabels(field)
 
-	if q.LegendFormat == legendFormatAuto && len(labels) > 0 {
-		return ""
-	}
-
-	if q.LegendFormat != "" {
+	if q.LegendFormat == legendFormatAuto {
+		if len(labels) > 0 {
+			legend = ""
+		}
+	} else if q.LegendFormat != "" {
 		result := legendFormatRegexp.ReplaceAllFunc([]byte(q.LegendFormat), func(in []byte) []byte {
 			labelName := strings.Replace(string(in), "{{", "", 1)
 			labelName = strings.Replace(labelName, "}}", "", 1)