Prometheus: Fix some of the alerting queries that use reduce/math operation (#44380)

* Prometheus: Dont fill response with nulls for alerting queries

* Refactor based on reviews

pkg/tsdb/prometheus/framing_test.go

@@ -132,5 +132,5 @@ func runQuery(response []byte, query PrometheusQuery) (*backend.QueryDataRespons
 	}
 
 	s := Service{tracer: tracer}
-	return s.runQueries(context.Background(), api, []*PrometheusQuery{&query})
+	return s.runQueries(context.Background(), api, []*PrometheusQuery{&query}, true)
 }

pkg/tsdb/prometheus/prometeus_bench_test.go

@@ -28,7 +28,7 @@ func BenchmarkJson(b *testing.B) {
 
 	b.ResetTimer()
 	for n := 0; n < b.N; n++ {
-		_, _ = s.runQueries(context.Background(), api, []*PrometheusQuery{&query})
+		_, _ = s.runQueries(context.Background(), api, []*PrometheusQuery{&query}, true)
 	}
 }
 

pkg/tsdb/prometheus/time_series_query.go

@@ -47,7 +47,7 @@ const (
 	ExemplarQueryType TimeSeriesQueryType = "exemplar"
 )
 
-func (s *Service) runQueries(ctx context.Context, client apiv1.API, queries []*PrometheusQuery) (*backend.QueryDataResponse, error) {
+func (s *Service) runQueries(ctx context.Context, client apiv1.API, queries []*PrometheusQuery, fillNulls bool) (*backend.QueryDataResponse, error) {
 	result := backend.QueryDataResponse{
 		Responses: backend.Responses{},
 	}
@@ -101,7 +101,7 @@ func (s *Service) runQueries(ctx context.Context, client apiv1.API, queries []*P
 			}
 		}
 
-		frames, err := parseTimeSeriesResponse(response, query)
+		frames, err := parseTimeSeriesResponse(response, query, fillNulls)
 		if err != nil {
 			return &result, err
 		}
@@ -128,7 +128,12 @@ func (s *Service) executeTimeSeriesQuery(ctx context.Context, req *backend.Query
 		return &result, err
 	}
 
-	return s.runQueries(ctx, client, queries)
+	fillNulls := true
+	if req.Headers["FromAlert"] == "true" {
+		fillNulls = false
+	}
+
+	return s.runQueries(ctx, client, queries, fillNulls)
 }
 
 func formatLegend(metric model.Metric, query *PrometheusQuery) string {
@@ -202,7 +207,7 @@ func (s *Service) parseTimeSeriesQuery(queryContext *backend.QueryDataRequest, d
 	return qs, nil
 }
 
-func parseTimeSeriesResponse(value map[TimeSeriesQueryType]interface{}, query *PrometheusQuery) (data.Frames, error) {
+func parseTimeSeriesResponse(value map[TimeSeriesQueryType]interface{}, query *PrometheusQuery, fillNulls bool) (data.Frames, error) {
 	var (
 		frames     = data.Frames{}
 		nextFrames = data.Frames{}
@@ -214,7 +219,11 @@ func parseTimeSeriesResponse(value map[TimeSeriesQueryType]interface{}, query *P
 
 		switch v := value.(type) {
 		case model.Matrix:
-			nextFrames = matrixToDataFrames(v, query, nextFrames)
+			if fillNulls {
+				nextFrames = matrixToDataFramesWithNullFill(v, query, nextFrames)
+			} else {
+				nextFrames = matrixToDataFrames(v, query, nextFrames)
+			}
 		case model.Vector:
 			nextFrames = vectorToDataFrames(v, query, nextFrames)
 		case *model.Scalar:
@@ -308,7 +317,7 @@ func interpolateVariables(model *QueryModel, interval time.Duration, timeRange t
 	return expr
 }
 
-func matrixToDataFrames(matrix model.Matrix, query *PrometheusQuery, frames data.Frames) data.Frames {
+func matrixToDataFramesWithNullFill(matrix model.Matrix, query *PrometheusQuery, frames data.Frames) data.Frames {
 	for _, v := range matrix {
 		tags := make(map[string]string, len(v.Metric))
 		for k, v := range v.Metric {
@@ -358,6 +367,35 @@ func matrixToDataFrames(matrix model.Matrix, query *PrometheusQuery, frames data
 	return frames
 }
 
+func matrixToDataFrames(matrix model.Matrix, query *PrometheusQuery, frames data.Frames) data.Frames {
+	for _, v := range matrix {
+		tags := make(map[string]string, len(v.Metric))
+		for k, v := range v.Metric {
+			tags[string(k)] = string(v)
+		}
+		timeField := data.NewFieldFromFieldType(data.FieldTypeTime, len(v.Values))
+		valueField := data.NewFieldFromFieldType(data.FieldTypeNullableFloat64, len(v.Values))
+
+		for i, k := range v.Values {
+			timeField.Set(i, time.Unix(k.Timestamp.Unix(), 0).UTC())
+			value := float64(k.Value)
+
+			if !math.IsNaN(value) {
+				valueField.Set(i, &value)
+			}
+		}
+
+		name := formatLegend(v.Metric, query)
+		timeField.Name = data.TimeSeriesTimeFieldName
+		valueField.Name = data.TimeSeriesValueFieldName
+		valueField.Config = &data.FieldConfig{DisplayNameFromDS: name}
+		valueField.Labels = tags
+		frames = append(frames, newDataFrame(name, "matrix", timeField, valueField))
+	}
+
+	return frames
+}
+
 func scalarToDataFrames(scalar *model.Scalar, query *PrometheusQuery, frames data.Frames) data.Frames {
 	timeVector := []time.Time{time.Unix(scalar.Timestamp.Unix(), 0).UTC()}
 	values := []float64{float64(scalar.Value)}

pkg/tsdb/prometheus/time_series_query_test.go

@@ -556,7 +556,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 		query := &PrometheusQuery{
 			LegendFormat: "legend {{app}}",
 		}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 		require.NoError(t, err)
 
 		// Test fields
@@ -594,7 +594,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 			End:          time.Unix(5, 0).UTC(),
 			UtcOffsetSec: 0,
 		}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 		require.NoError(t, err)
 
 		require.Len(t, res, 1)
@@ -631,7 +631,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 			End:          time.Unix(4, 0).UTC(),
 			UtcOffsetSec: 0,
 		}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 
 		require.NoError(t, err)
 		require.Len(t, res, 1)
@@ -643,6 +643,39 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 		require.Nil(t, res[0].Fields[1].At(2))
 	})
 
+	t.Run("matrix response with from alerting missed data points should be parsed correctly", func(t *testing.T) {
+		values := []p.SamplePair{
+			{Value: 1, Timestamp: 1000},
+			{Value: 4, Timestamp: 4000},
+		}
+		value := make(map[TimeSeriesQueryType]interface{})
+		value[RangeQueryType] = p.Matrix{
+			&p.SampleStream{
+				Metric: p.Metric{"app": "Application", "tag2": "tag2"},
+				Values: values,
+			},
+		}
+		query := &PrometheusQuery{
+			LegendFormat: "",
+			Step:         1 * time.Second,
+			Start:        time.Unix(1, 0).UTC(),
+			End:          time.Unix(4, 0).UTC(),
+			UtcOffsetSec: 0,
+		}
+		res, err := parseTimeSeriesResponse(value, query, false)
+
+		require.NoError(t, err)
+		require.Len(t, res, 1)
+		require.Equal(t, res[0].Name, "{app=\"Application\", tag2=\"tag2\"}")
+		require.Len(t, res[0].Fields, 2)
+		require.Len(t, res[0].Fields[0].Labels, 0)
+		require.Equal(t, res[0].Fields[0].Name, "Time")
+		require.Len(t, res[0].Fields[1].Labels, 2)
+		require.Equal(t, res[0].Fields[1].Labels.String(), "app=Application, tag2=tag2")
+		require.Equal(t, res[0].Fields[1].Name, "Value")
+		require.Equal(t, res[0].Fields[1].Config.DisplayNameFromDS, "{app=\"Application\", tag2=\"tag2\"}")
+	})
+
 	t.Run("matrix response with NaN value should be changed to null", func(t *testing.T) {
 		value := make(map[TimeSeriesQueryType]interface{})
 		value[RangeQueryType] = p.Matrix{
@@ -660,7 +693,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 			End:          time.Unix(4, 0).UTC(),
 			UtcOffsetSec: 0,
 		}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 		require.NoError(t, err)
 
 		var nilPointer *float64
@@ -680,7 +713,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 		query := &PrometheusQuery{
 			LegendFormat: "legend {{app}}",
 		}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 		require.NoError(t, err)
 
 		require.Len(t, res, 1)
@@ -707,7 +740,7 @@ func TestPrometheus_parseTimeSeriesResponse(t *testing.T) {
 		}
 
 		query := &PrometheusQuery{}
-		res, err := parseTimeSeriesResponse(value, query)
+		res, err := parseTimeSeriesResponse(value, query, true)
 		require.NoError(t, err)
 
 		require.Len(t, res, 1)