Elasticsearch: Add Top Metrics Aggregation and X-Pack support (#33041)

* Elasticsearch: Add Top Metrics Aggregation

* Adding support for non-timeseries visualizations

* removing console.logs

* restoring loadOptions type

* Honor xpack setting

* Adding test for elastic_response

* adding test for query builder

* Adding support of alerting

* Fixing separator spelling

* Fixing linting issues

* attempting to reduce cyclomatic complexity

* Adding elastic77 Docker block

* Update public/app/plugins/datasource/elasticsearch/components/QueryEditor/MetricAggregationsEditor/MetricEditor.test.tsx

Co-authored-by: Giordano Ricci <grdnricci@gmail.com>

* refactoring MetricsEditor tests

* Fixing typo

* Change getFields type & move TopMetrics to a separate component

* Fix SegmentAsync styles in TopMetrics Settings

* Fix field types for TopMetrics

* WIP

* Refactoring client side to support multiple top metrics

* Adding tests and finishing go implimentation

* removing fmt lib from debugging

* fixing tests

* reducing the cyclomatic complexity

* Update public/app/plugins/datasource/elasticsearch/elastic_response.ts

Co-authored-by: Giordano Ricci <grdnricci@gmail.com>

* Update public/app/plugins/datasource/elasticsearch/hooks/useFields.ts

Co-authored-by: Giordano Ricci <grdnricci@gmail.com>

* Checking for possible nil value

* Fixing types

* fix fake-data-gen param

* fix useFields hook

* Removing aggregateBy and size

* Fixing go tests

* Fixing TS tests

* fixing tests

* Fixes

* Remove date from top_metrics fields

* Restore previous formatting

* Update pkg/tsdb/elasticsearch/client/models.go

Co-authored-by: Dimitris Sotirakis <dimitrios.sotirakis@grafana.com>

* Update pkg/tsdb/elasticsearch/client/models.go

Co-authored-by: Dimitris Sotirakis <dimitrios.sotirakis@grafana.com>

* Fix code review comments on processTopMetricValue

* Remove underscore from variable names

* Remove intermediate array definition

* Refactor test to use testify

Co-authored-by: Giordano Ricci <grdnricci@gmail.com>
Co-authored-by: Elfo404 <me@giordanoricci.com>
Co-authored-by: Dimitris Sotirakis <dimitrios.sotirakis@grafana.com>

pkg/tsdb/elasticsearch/client/client.go

@@ -53,6 +53,8 @@ func coerceVersion(v *simplejson.Json) (*semver.Version, error) {
 			return nil, err
 		}
 
+		// Legacy version numbers (before Grafana 8)
+		// valid values were 2,5,56,60,70
 		switch versionNumber {
 		case 2:
 			return semver.NewVersion("2.0.0")

pkg/tsdb/elasticsearch/client/models.go

@@ -274,12 +274,41 @@ type GeoHashGridAggregation struct {
 
 // MetricAggregation represents a metric aggregation
 type MetricAggregation struct {
+	Type     string
 	Field    string
 	Settings map[string]interface{}
 }
 
 // MarshalJSON returns the JSON encoding of the metric aggregation
 func (a *MetricAggregation) MarshalJSON() ([]byte, error) {
+	if a.Type == "top_metrics" {
+		root := map[string]interface{}{}
+		var rootMetrics []map[string]string
+
+		order, hasOrder := a.Settings["order"]
+		orderBy, hasOrderBy := a.Settings["orderBy"]
+
+		root["size"] = "1"
+
+		metrics, hasMetrics := a.Settings["metrics"].([]interface{})
+		if hasMetrics {
+			for _, v := range metrics {
+				metricValue := map[string]string{"field": v.(string)}
+				rootMetrics = append(rootMetrics, metricValue)
+			}
+			root["metrics"] = rootMetrics
+		}
+
+		if hasOrderBy && hasOrder {
+			root["sort"] = []map[string]interface{}{
+				{
+					orderBy.(string): order,
+				},
+			}
+		}
+
+		return json.Marshal(root)
+	}
 	root := map[string]interface{}{}
 
 	if a.Field != "" {

pkg/tsdb/elasticsearch/client/search_request.go

@@ -419,9 +419,11 @@ func (b *aggBuilderImpl) GeoHashGrid(key, field string, fn func(a *GeoHashGridAg
 
 func (b *aggBuilderImpl) Metric(key, metricType, field string, fn func(a *MetricAggregation)) AggBuilder {
 	innerAgg := &MetricAggregation{
+		Type:     metricType,
 		Field:    field,
 		Settings: make(map[string]interface{}),
 	}
+
 	aggDef := newAggDef(key, &aggContainer{
 		Type:        metricType,
 		Aggregation: innerAgg,