Add support for tsdb endpoint (#773)

Signed-off-by: Hima Varsha <hdureddy@apple.com>

api/prometheus/v1/api.go

@@ -138,6 +138,7 @@ const (
 	epConfig          = apiPrefix + "/status/config"
 	epFlags           = apiPrefix + "/status/flags"
 	epRuntimeinfo     = apiPrefix + "/status/runtimeinfo"
+	epTSDB            = apiPrefix + "/status/tsdb"
 )
 
 // AlertState models the state of an alert.
@@ -254,6 +255,8 @@ type API interface {
 	TargetsMetadata(ctx context.Context, matchTarget string, metric string, limit string) ([]MetricMetadata, error)
 	// Metadata returns metadata about metrics currently scraped by the metric name.
 	Metadata(ctx context.Context, metric string, limit string) (map[string][]Metadata, error)
+	// TSDB returns the cardinality statistics.
+	TSDB(ctx context.Context) (TSDBResult, error)
 }
 
 // AlertsResult contains the result from querying the alerts endpoint.
@@ -404,6 +407,20 @@ type queryResult struct {
 	v model.Value
 }
 
+// TSDBResult contains the result from querying the tsdb endpoint.
+type TSDBResult struct {
+	SeriesCountByMetricName     []Stat `json:"seriesCountByMetricName"`
+	LabelValueCountByLabelName  []Stat `json:"labelValueCountByLabelName"`
+	MemoryInBytesByLabelName    []Stat `json:"memoryInBytesByLabelName"`
+	SeriesCountByLabelValuePair []Stat `json:"seriesCountByLabelValuePair"`
+}
+
+// Stat models information about statistic value.
+type Stat struct {
+	Name  string `json:"name"`
+	Value uint64 `json:"value"`
+}
+
 func (rg *RuleGroup) UnmarshalJSON(b []byte) error {
 	v := struct {
 		Name     string            `json:"name"`
@@ -883,6 +900,24 @@ func (h *httpAPI) Metadata(ctx context.Context, metric string, limit string) (ma
 	return res, json.Unmarshal(body, &res)
 }
 
+func (h *httpAPI) TSDB(ctx context.Context) (TSDBResult, error) {
+	u := h.client.URL(epTSDB, nil)
+
+	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+	if err != nil {
+		return TSDBResult{}, err
+	}
+
+	_, body, _, err := h.client.Do(ctx, req)
+	if err != nil {
+		return TSDBResult{}, err
+	}
+
+	var res TSDBResult
+	return res, json.Unmarshal(body, &res)
+
+}
+
 // Warnings is an array of non critical errors
 type Warnings []string
 

api/prometheus/v1/api_test.go

@@ -216,6 +216,13 @@ func TestAPIs(t *testing.T) {
 		}
 	}
 
+	doTSDB := func() func() (interface{}, Warnings, error) {
+		return func() (interface{}, Warnings, error) {
+			v, err := promAPI.TSDB(context.Background())
+			return v, nil, err
+		}
+	}
+
 	queryTests := []apiTest{
 		{
 			do: doQuery("2", testTime),
@@ -953,6 +960,72 @@ func TestAPIs(t *testing.T) {
 			},
 			err: fmt.Errorf("some error"),
 		},
+
+		{
+			do:        doTSDB(),
+			reqMethod: "GET",
+			reqPath:   "/api/v1/status/tsdb",
+			inErr:     fmt.Errorf("some error"),
+			err:       fmt.Errorf("some error"),
+		},
+
+		{
+			do:        doTSDB(),
+			reqMethod: "GET",
+			reqPath:   "/api/v1/status/tsdb",
+			inRes: map[string]interface{}{
+				"seriesCountByMetricName": []interface{}{
+					map[string]interface{}{
+						"name":  "kubelet_http_requests_duration_seconds_bucket",
+						"value": 1000,
+					},
+				},
+				"labelValueCountByLabelName": []interface{}{
+					map[string]interface{}{
+						"name":  "__name__",
+						"value": 200,
+					},
+				},
+				"memoryInBytesByLabelName": []interface{}{
+					map[string]interface{}{
+						"name":  "id",
+						"value": 4096,
+					},
+				},
+				"seriesCountByLabelValuePair": []interface{}{
+					map[string]interface{}{
+						"name":  "job=kubelet",
+						"value": 30000,
+					},
+				},
+			},
+			res: TSDBResult{
+				SeriesCountByMetricName: []Stat{
+					{
+						Name:  "kubelet_http_requests_duration_seconds_bucket",
+						Value: 1000,
+					},
+				},
+				LabelValueCountByLabelName: []Stat{
+					{
+						Name:  "__name__",
+						Value: 200,
+					},
+				},
+				MemoryInBytesByLabelName: []Stat{
+					{
+						Name:  "id",
+						Value: 4096,
+					},
+				},
+				SeriesCountByLabelValuePair: []Stat{
+					{
+						Name:  "job=kubelet",
+						Value: 30000,
+					},
+				},
+			},
+		},
 	}
 
 	var tests []apiTest