Elasticsearch: Fix pre-v7.0 and alerting error (#16904)

This fixes a regression introduced in #16646 where using Elasticsearch 
pre-v7.0 and alerting resulted in an error when trying to deserialize the 
response of total number of hits.
Total number of hits is not in use by the backend so we're removing it 
for now to make ES 6 and 7 being able to deserialize search responses 
without errors.

Closes #15622

pkg/tsdb/elasticsearch/client/client_test.go

@@ -118,247 +118,250 @@ func TestClient(t *testing.T) {
 			})
 		})
 
-		Convey("Given a fake http client", func() {
-			var responseBuffer *bytes.Buffer
-			var req *http.Request
-			ts := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
-				req = r
-				buf, err := ioutil.ReadAll(r.Body)
-				if err != nil {
-					t.Fatalf("Failed to read response body, err=%v", err)
-				}
-				responseBuffer = bytes.NewBuffer(buf)
-			}))
-
-			currentNewDatasourceHttpClient := newDatasourceHttpClient
-
-			newDatasourceHttpClient = func(ds *models.DataSource) (*http.Client, error) {
-				return ts.Client(), nil
-			}
-
-			from := time.Date(2018, 5, 15, 17, 50, 0, 0, time.UTC)
-			to := time.Date(2018, 5, 15, 17, 55, 0, 0, time.UTC)
-			fromStr := fmt.Sprintf("%d", from.UnixNano()/int64(time.Millisecond))
-			toStr := fmt.Sprintf("%d", to.UnixNano()/int64(time.Millisecond))
-			timeRange := tsdb.NewTimeRange(fromStr, toStr)
-
-			Convey("and a v2.x client", func() {
-				ds := models.DataSource{
-					Database: "[metrics-]YYYY.MM.DD",
-					Url:      ts.URL,
-					JsonData: simplejson.NewFromAny(map[string]interface{}{
-						"esVersion": 2,
-						"timeField": "@timestamp",
-						"interval":  "Daily",
-					}),
-				}
-
-				c, err := NewClient(context.Background(), &ds, timeRange)
+		httpClientScenario(t, "Given a fake http client and a v2.x client with response", &models.DataSource{
+			Database: "[metrics-]YYYY.MM.DD",
+			JsonData: simplejson.NewFromAny(map[string]interface{}{
+				"esVersion": 2,
+				"timeField": "@timestamp",
+				"interval":  "Daily",
+			}),
+		}, func(sc *scenarioContext) {
+			sc.responseBody = `{
+				"responses": [
+					{
+						"hits": {	"hits": [], "max_score": 0,	"total": 4656	},
+						"status": 200
+					}
+				]
+			}`
+
+			Convey("When executing multi search", func() {
+				ms, err := createMultisearchForTest(sc.client)
+				So(err, ShouldBeNil)
+				res, err := sc.client.ExecuteMultisearch(ms)
 				So(err, ShouldBeNil)
-				So(c, ShouldNotBeNil)
-
-				Convey("When executing multi search", func() {
-					ms, err := createMultisearchForTest(c)
-					So(err, ShouldBeNil)
-					c.ExecuteMultisearch(ms)
 
-					Convey("Should send correct request and payload", func() {
-						So(req, ShouldNotBeNil)
-						So(req.Method, ShouldEqual, http.MethodPost)
-						So(req.URL.Path, ShouldEqual, "/_msearch")
+				Convey("Should send correct request and payload", func() {
+					So(sc.request, ShouldNotBeNil)
+					So(sc.request.Method, ShouldEqual, http.MethodPost)
+					So(sc.request.URL.Path, ShouldEqual, "/_msearch")
 
-						So(responseBuffer, ShouldNotBeNil)
+					So(sc.requestBody, ShouldNotBeNil)
 
-						headerBytes, err := responseBuffer.ReadBytes('\n')
-						So(err, ShouldBeNil)
-						bodyBytes := responseBuffer.Bytes()
+					headerBytes, err := sc.requestBody.ReadBytes('\n')
+					So(err, ShouldBeNil)
+					bodyBytes := sc.requestBody.Bytes()
 
-						jHeader, err := simplejson.NewJson(headerBytes)
-						So(err, ShouldBeNil)
+					jHeader, err := simplejson.NewJson(headerBytes)
+					So(err, ShouldBeNil)
 
-						jBody, err := simplejson.NewJson(bodyBytes)
-						So(err, ShouldBeNil)
+					jBody, err := simplejson.NewJson(bodyBytes)
+					So(err, ShouldBeNil)
 
-						So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
-						So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
-						So(jHeader.Get("search_type").MustString(), ShouldEqual, "count")
-						So(jHeader.Get("max_concurrent_shard_requests").MustInt(10), ShouldEqual, 10)
+					So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
+					So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
+					So(jHeader.Get("search_type").MustString(), ShouldEqual, "count")
+					So(jHeader.Get("max_concurrent_shard_requests").MustInt(10), ShouldEqual, 10)
 
-						Convey("and replace $__interval variable", func() {
-							So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
-						})
+					Convey("and replace $__interval variable", func() {
+						So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
+					})
 
-						Convey("and replace $__interval_ms variable", func() {
-							So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
-						})
+					Convey("and replace $__interval_ms variable", func() {
+						So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
 					})
 				})
-			})
 
-			Convey("and a v5.x client", func() {
-				ds := models.DataSource{
-					Database: "[metrics-]YYYY.MM.DD",
-					Url:      ts.URL,
-					JsonData: simplejson.NewFromAny(map[string]interface{}{
-						"esVersion":                  5,
-						"maxConcurrentShardRequests": 100,
-						"timeField":                  "@timestamp",
-						"interval":                   "Daily",
-					}),
-				}
+				Convey("Should parse response", func() {
+					So(res.Status, ShouldEqual, 200)
+					So(res.Responses, ShouldHaveLength, 1)
+				})
+			})
+		})
 
-				c, err := NewClient(context.Background(), &ds, timeRange)
+		httpClientScenario(t, "Given a fake http client and a v5.x client with response", &models.DataSource{
+			Database: "[metrics-]YYYY.MM.DD",
+			JsonData: simplejson.NewFromAny(map[string]interface{}{
+				"esVersion":                  5,
+				"maxConcurrentShardRequests": 100,
+				"timeField":                  "@timestamp",
+				"interval":                   "Daily",
+			}),
+		}, func(sc *scenarioContext) {
+			sc.responseBody = `{
+				"responses": [
+					{
+						"hits": {	"hits": [], "max_score": 0,	"total": 4656	},
+						"status": 200
+					}
+				]
+			}`
+
+			Convey("When executing multi search", func() {
+				ms, err := createMultisearchForTest(sc.client)
+				So(err, ShouldBeNil)
+				res, err := sc.client.ExecuteMultisearch(ms)
 				So(err, ShouldBeNil)
-				So(c, ShouldNotBeNil)
-
-				Convey("When executing multi search", func() {
-					ms, err := createMultisearchForTest(c)
-					So(err, ShouldBeNil)
-					c.ExecuteMultisearch(ms)
 
-					Convey("Should send correct request and payload", func() {
-						So(req, ShouldNotBeNil)
-						So(req.Method, ShouldEqual, http.MethodPost)
-						So(req.URL.Path, ShouldEqual, "/_msearch")
+				Convey("Should send correct request and payload", func() {
+					So(sc.request, ShouldNotBeNil)
+					So(sc.request.Method, ShouldEqual, http.MethodPost)
+					So(sc.request.URL.Path, ShouldEqual, "/_msearch")
 
-						So(responseBuffer, ShouldNotBeNil)
+					So(sc.requestBody, ShouldNotBeNil)
 
-						headerBytes, err := responseBuffer.ReadBytes('\n')
-						So(err, ShouldBeNil)
-						bodyBytes := responseBuffer.Bytes()
+					headerBytes, err := sc.requestBody.ReadBytes('\n')
+					So(err, ShouldBeNil)
+					bodyBytes := sc.requestBody.Bytes()
 
-						jHeader, err := simplejson.NewJson(headerBytes)
-						So(err, ShouldBeNil)
+					jHeader, err := simplejson.NewJson(headerBytes)
+					So(err, ShouldBeNil)
 
-						jBody, err := simplejson.NewJson(bodyBytes)
-						So(err, ShouldBeNil)
+					jBody, err := simplejson.NewJson(bodyBytes)
+					So(err, ShouldBeNil)
 
-						So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
-						So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
-						So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
-						So(jHeader.Get("max_concurrent_shard_requests").MustInt(10), ShouldEqual, 10)
+					So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
+					So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
+					So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
+					So(jHeader.Get("max_concurrent_shard_requests").MustInt(10), ShouldEqual, 10)
 
-						Convey("and replace $__interval variable", func() {
-							So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
-						})
+					Convey("and replace $__interval variable", func() {
+						So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
+					})
 
-						Convey("and replace $__interval_ms variable", func() {
-							So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
-						})
+					Convey("and replace $__interval_ms variable", func() {
+						So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
 					})
 				})
-			})
 
-			Convey("and a v5.6 client", func() {
-				ds := models.DataSource{
-					Database: "[metrics-]YYYY.MM.DD",
-					Url:      ts.URL,
-					JsonData: simplejson.NewFromAny(map[string]interface{}{
-						"esVersion":                  56,
-						"maxConcurrentShardRequests": 100,
-						"timeField":                  "@timestamp",
-						"interval":                   "Daily",
-					}),
-				}
+				Convey("Should parse response", func() {
+					So(res.Status, ShouldEqual, 200)
+					So(res.Responses, ShouldHaveLength, 1)
+				})
+			})
+		})
 
-				c, err := NewClient(context.Background(), &ds, timeRange)
+		httpClientScenario(t, "Given a fake http client and a v5.6 client with response", &models.DataSource{
+			Database: "[metrics-]YYYY.MM.DD",
+			JsonData: simplejson.NewFromAny(map[string]interface{}{
+				"esVersion":                  56,
+				"maxConcurrentShardRequests": 100,
+				"timeField":                  "@timestamp",
+				"interval":                   "Daily",
+			}),
+		}, func(sc *scenarioContext) {
+			sc.responseBody = `{
+				"responses": [
+					{
+						"hits": {	"hits": [], "max_score": 0,	"total": 4656	},
+						"status": 200
+					}
+				]
+			}`
+
+			Convey("When executing multi search", func() {
+				ms, err := createMultisearchForTest(sc.client)
+				So(err, ShouldBeNil)
+				res, err := sc.client.ExecuteMultisearch(ms)
 				So(err, ShouldBeNil)
-				So(c, ShouldNotBeNil)
-
-				Convey("When executing multi search", func() {
-					ms, err := createMultisearchForTest(c)
-					So(err, ShouldBeNil)
-					c.ExecuteMultisearch(ms)
 
-					Convey("Should send correct request and payload", func() {
-						So(req, ShouldNotBeNil)
-						So(req.Method, ShouldEqual, http.MethodPost)
-						So(req.URL.Path, ShouldEqual, "/_msearch")
+				Convey("Should send correct request and payload", func() {
+					So(sc.request, ShouldNotBeNil)
+					So(sc.request.Method, ShouldEqual, http.MethodPost)
+					So(sc.request.URL.Path, ShouldEqual, "/_msearch")
 
-						So(responseBuffer, ShouldNotBeNil)
+					So(sc.requestBody, ShouldNotBeNil)
 
-						headerBytes, err := responseBuffer.ReadBytes('\n')
-						So(err, ShouldBeNil)
-						bodyBytes := responseBuffer.Bytes()
+					headerBytes, err := sc.requestBody.ReadBytes('\n')
+					So(err, ShouldBeNil)
+					bodyBytes := sc.requestBody.Bytes()
 
-						jHeader, err := simplejson.NewJson(headerBytes)
-						So(err, ShouldBeNil)
+					jHeader, err := simplejson.NewJson(headerBytes)
+					So(err, ShouldBeNil)
 
-						jBody, err := simplejson.NewJson(bodyBytes)
-						So(err, ShouldBeNil)
+					jBody, err := simplejson.NewJson(bodyBytes)
+					So(err, ShouldBeNil)
 
-						So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
-						So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
-						So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
-						So(jHeader.Get("max_concurrent_shard_requests").MustInt(), ShouldEqual, 100)
+					So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
+					So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
+					So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
+					So(jHeader.Get("max_concurrent_shard_requests").MustInt(), ShouldEqual, 100)
 
-						Convey("and replace $__interval variable", func() {
-							So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
-						})
+					Convey("and replace $__interval variable", func() {
+						So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
+					})
 
-						Convey("and replace $__interval_ms variable", func() {
-							So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
-						})
+					Convey("and replace $__interval_ms variable", func() {
+						So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
 					})
 				})
-			})
 
-			Convey("and a v7.0 client", func() {
-				ds := models.DataSource{
-					Database: "[metrics-]YYYY.MM.DD",
-					Url:      ts.URL,
-					JsonData: simplejson.NewFromAny(map[string]interface{}{
-						"esVersion":                  70,
-						"maxConcurrentShardRequests": 6,
-						"timeField":                  "@timestamp",
-						"interval":                   "Daily",
-					}),
-				}
+				Convey("Should parse response", func() {
+					So(res.Status, ShouldEqual, 200)
+					So(res.Responses, ShouldHaveLength, 1)
+				})
+			})
+		})
 
-				c, err := NewClient(context.Background(), &ds, timeRange)
+		httpClientScenario(t, "Given a fake http client and a v7.0 client with response", &models.DataSource{
+			Database: "[metrics-]YYYY.MM.DD",
+			JsonData: simplejson.NewFromAny(map[string]interface{}{
+				"esVersion":                  70,
+				"maxConcurrentShardRequests": 6,
+				"timeField":                  "@timestamp",
+				"interval":                   "Daily",
+			}),
+		}, func(sc *scenarioContext) {
+			sc.responseBody = `{
+				"responses": [
+					{
+						"hits": {	"hits": [], "max_score": 0,	"total": { "value": 4656, "relation": "eq"}	},
+						"status": 200
+					}
+				]
+			}`
+
+			Convey("When executing multi search", func() {
+				ms, err := createMultisearchForTest(sc.client)
+				So(err, ShouldBeNil)
+				res, err := sc.client.ExecuteMultisearch(ms)
 				So(err, ShouldBeNil)
-				So(c, ShouldNotBeNil)
-
-				Convey("When executing multi search", func() {
-					ms, err := createMultisearchForTest(c)
-					So(err, ShouldBeNil)
-					c.ExecuteMultisearch(ms)
 
-					Convey("Should send correct request and payload", func() {
-						So(req, ShouldNotBeNil)
-						So(req.Method, ShouldEqual, http.MethodPost)
-						So(req.URL.Path, ShouldEqual, "/_msearch")
-						So(req.URL.RawQuery, ShouldEqual, "max_concurrent_shard_requests=6")
+				Convey("Should send correct request and payload", func() {
+					So(sc.request, ShouldNotBeNil)
+					So(sc.request.Method, ShouldEqual, http.MethodPost)
+					So(sc.request.URL.Path, ShouldEqual, "/_msearch")
+					So(sc.request.URL.RawQuery, ShouldEqual, "max_concurrent_shard_requests=6")
 
-						So(responseBuffer, ShouldNotBeNil)
+					So(sc.requestBody, ShouldNotBeNil)
 
-						headerBytes, err := responseBuffer.ReadBytes('\n')
-						So(err, ShouldBeNil)
-						bodyBytes := responseBuffer.Bytes()
+					headerBytes, err := sc.requestBody.ReadBytes('\n')
+					So(err, ShouldBeNil)
+					bodyBytes := sc.requestBody.Bytes()
 
-						jHeader, err := simplejson.NewJson(headerBytes)
-						So(err, ShouldBeNil)
+					jHeader, err := simplejson.NewJson(headerBytes)
+					So(err, ShouldBeNil)
 
-						jBody, err := simplejson.NewJson(bodyBytes)
-						So(err, ShouldBeNil)
+					jBody, err := simplejson.NewJson(bodyBytes)
+					So(err, ShouldBeNil)
 
-						So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
-						So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
-						So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
+					So(jHeader.Get("index").MustString(), ShouldEqual, "metrics-2018.05.15")
+					So(jHeader.Get("ignore_unavailable").MustBool(false), ShouldEqual, true)
+					So(jHeader.Get("search_type").MustString(), ShouldEqual, "query_then_fetch")
 
-						Convey("and replace $__interval variable", func() {
-							So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
-						})
+					Convey("and replace $__interval variable", func() {
+						So(jBody.GetPath("aggs", "2", "aggs", "1", "avg", "script").MustString(), ShouldEqual, "15000*@hostname")
+					})
 
-						Convey("and replace $__interval_ms variable", func() {
-							So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
-						})
+					Convey("and replace $__interval_ms variable", func() {
+						So(jBody.GetPath("aggs", "2", "date_histogram", "interval").MustString(), ShouldEqual, "15s")
 					})
 				})
-			})
 
-			Reset(func() {
-				newDatasourceHttpClient = currentNewDatasourceHttpClient
+				Convey("Should parse response", func() {
+					So(res.Status, ShouldEqual, 200)
+					So(res.Responses, ShouldHaveLength, 1)
+				})
 			})
 		})
 	})
@@ -376,3 +379,61 @@ func createMultisearchForTest(c Client) (*MultiSearchRequest, error) {
 	})
 	return msb.Build()
 }
+
+type scenarioContext struct {
+	client         Client
+	request        *http.Request
+	requestBody    *bytes.Buffer
+	responseStatus int
+	responseBody   string
+}
+
+type scenarioFunc func(*scenarioContext)
+
+func httpClientScenario(t *testing.T, desc string, ds *models.DataSource, fn scenarioFunc) {
+	t.Helper()
+
+	Convey(desc, func() {
+		sc := &scenarioContext{
+			responseStatus: 200,
+			responseBody:   `{ "responses": [] }`,
+		}
+		ts := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+			sc.request = r
+			buf, err := ioutil.ReadAll(r.Body)
+			if err != nil {
+				t.Fatalf("Failed to read request body, err=%v", err)
+			}
+			sc.requestBody = bytes.NewBuffer(buf)
+
+			rw.Header().Add("Content-Type", "application/json")
+			rw.Write([]byte(sc.responseBody))
+			rw.WriteHeader(sc.responseStatus)
+		}))
+		ds.Url = ts.URL
+
+		from := time.Date(2018, 5, 15, 17, 50, 0, 0, time.UTC)
+		to := time.Date(2018, 5, 15, 17, 55, 0, 0, time.UTC)
+		fromStr := fmt.Sprintf("%d", from.UnixNano()/int64(time.Millisecond))
+		toStr := fmt.Sprintf("%d", to.UnixNano()/int64(time.Millisecond))
+		timeRange := tsdb.NewTimeRange(fromStr, toStr)
+
+		c, err := NewClient(context.Background(), ds, timeRange)
+		So(err, ShouldBeNil)
+		So(c, ShouldNotBeNil)
+		sc.client = c
+
+		currentNewDatasourceHttpClient := newDatasourceHttpClient
+
+		newDatasourceHttpClient = func(ds *models.DataSource) (*http.Client, error) {
+			return ts.Client(), nil
+		}
+
+		defer func() {
+			ts.Close()
+			newDatasourceHttpClient = currentNewDatasourceHttpClient
+		}()
+
+		fn(sc)
+	})
+}

pkg/tsdb/elasticsearch/client/models.go

@@ -41,8 +41,7 @@ func (r *SearchRequest) MarshalJSON() ([]byte, error) {
 
 // SearchResponseHits represents search response hits
 type SearchResponseHits struct {
-	Hits  []map[string]interface{}
-	Total map[string]interface{}
+	Hits []map[string]interface{}
 }
 
 // SearchResponse represents a search response
@@ -52,21 +51,6 @@ type SearchResponse struct {
 	Hits         *SearchResponseHits    `json:"hits"`
 }
 
-// func (r *Response) getErrMsg() string {
-// 	var msg bytes.Buffer
-// 	errJson := simplejson.NewFromAny(r.Err)
-// 	errType, err := errJson.Get("type").String()
-// 	if err == nil {
-// 		msg.WriteString(fmt.Sprintf("type:%s", errType))
-// 	}
-
-// 	reason, err := errJson.Get("type").String()
-// 	if err == nil {
-// 		msg.WriteString(fmt.Sprintf("reason:%s", reason))
-// 	}
-// 	return msg.String()
-// }
-
 // MultiSearchRequest represents a multi search request
 type MultiSearchRequest struct {
 	Requests []*SearchRequest