Graphite: Convert tag values returned as numbers to strings (#37882)

* Convert tag values returned as numbers to string

This is a bug in Graphite <= 1.1.7. Since 1.1.8 all values are converted to strings.

* Simplify type conversions

* Fix linting errors

pkg/tsdb/graphite/graphite.go

@@ -10,6 +10,7 @@ import (
 	"net/url"
 	"path"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -248,15 +249,25 @@ func (s *Service) toDataFrames(response *http.Response) (frames data.Frames, err
 			values = append(values, value)
 		}
 
+		tags := make(map[string]string)
+		for name, value := range series.Tags {
+			switch value := value.(type) {
+			case string:
+				tags[name] = value
+			case float64:
+				tags[name] = strconv.FormatFloat(value, 'f', -1, 64)
+			}
+		}
+
 		frames = append(frames, data.NewFrame(name,
 			data.NewField("time", nil, timeVector),
-			data.NewField("value", series.Tags, values).SetConfig(&data.FieldConfig{DisplayNameFromDS: name})))
+			data.NewField("value", tags, values).SetConfig(&data.FieldConfig{DisplayNameFromDS: name})))
 
 		if setting.Env == setting.Dev {
 			s.logger.Debug("Graphite response", "target", series.Target, "datapoints", len(series.DataPoints))
 		}
 	}
-	return
+	return frames, nil
 }
 
 func (s *Service) createRequest(dsInfo *datasourceInfo, data url.Values) (*http.Request, error) {

pkg/tsdb/graphite/graphite_test.go

@@ -52,12 +52,39 @@ func TestFixIntervalFormat(t *testing.T) {
 
 	service := &Service{logger: log.New("tsdb.graphite")}
 
-	t.Run("Converts response to data frames", func(*testing.T) {
+	t.Run("Converts response without tags to data frames", func(*testing.T) {
 		body := `
 		[
 			{
 				"target": "target",
-				"tags": { "fooTag": "fooValue", "barTag": "barValue" },
+				"datapoints": [[50, 1], [null, 2], [100, 3]]
+			}
+		]`
+		a := 50.0
+		b := 100.0
+		expectedFrame := data.NewFrame("target",
+			data.NewField("time", nil, []time.Time{time.Unix(1, 0).UTC(), time.Unix(2, 0).UTC(), time.Unix(3, 0).UTC()}),
+			data.NewField("value", data.Labels{}, []*float64{&a, nil, &b}).SetConfig(&data.FieldConfig{DisplayNameFromDS: "target"}),
+		)
+		expectedFrames := data.Frames{expectedFrame}
+
+		httpResponse := &http.Response{StatusCode: 200, Body: ioutil.NopCloser(strings.NewReader(body))}
+		dataFrames, err := service.toDataFrames(httpResponse)
+
+		require.NoError(t, err)
+		if !reflect.DeepEqual(expectedFrames, dataFrames) {
+			expectedFramesJSON, _ := json.Marshal(expectedFrames)
+			dataFramesJSON, _ := json.Marshal(dataFrames)
+			t.Errorf("Data frames should have been equal but was, expected:\n%s\nactual:\n%s", expectedFramesJSON, dataFramesJSON)
+		}
+	})
+
+	t.Run("Converts response with tags to data frames", func(*testing.T) {
+		body := `
+		[
+			{
+				"target": "target",
+				"tags": { "fooTag": "fooValue", "barTag": "barValue", "int": 100, "float": 3.14 },
 				"datapoints": [[50, 1], [null, 2], [100, 3]]
 			}
 		]`
@@ -68,6 +95,8 @@ func TestFixIntervalFormat(t *testing.T) {
 			data.NewField("value", data.Labels{
 				"fooTag": "fooValue",
 				"barTag": "barValue",
+				"int":    "100",
+				"float":  "3.14",
 			}, []*float64{&a, nil, &b}).SetConfig(&data.FieldConfig{DisplayNameFromDS: "target"}),
 		)
 		expectedFrames := data.Frames{expectedFrame}

pkg/tsdb/graphite/types.go

@@ -5,5 +5,6 @@ import "github.com/grafana/grafana/pkg/plugins"
 type TargetResponseDTO struct {
 	Target     string                       `json:"target"`
 	DataPoints plugins.DataTimeSeriesPoints `json:"datapoints"`
-	Tags       map[string]string            `json:"tags"`
+	// Graphite <=1.1.7 may return some tags as numbers requiring extra conversion. See https://github.com/grafana/grafana/issues/37614
+	Tags map[string]interface{} `json:"tags"`
 }