Elasticsearch: Run version check thorugh backend if enableElasticsearchBackendQuerying enabled (#67679)

* Elasticsearch: Run getDBversion trough resource calls

* Update

* Update

* Fix lint

* Close response body

* Fix lint

* Refactor

pkg/tsdb/elasticsearch/elasticsearch.go

@@ -1,10 +1,15 @@
 package elasticsearch
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"path"
 	"strconv"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
@@ -172,3 +177,66 @@ func (s *Service) getDSInfo(pluginCtx backend.PluginContext) (*es.DatasourceInfo
 
 	return &instance, nil
 }
+
+func (s *Service) CallResource(ctx context.Context, req *backend.CallResourceRequest, sender backend.CallResourceResponseSender) error {
+	logger := eslog.FromContext(ctx)
+	// allowed paths for resource calls:
+	// - empty string for fetching db version
+	if req.Path != "" {
+		return fmt.Errorf("invalid resource URL: %s", req.Path)
+	}
+
+	ds, err := s.getDSInfo(req.PluginContext)
+	if err != nil {
+		return err
+	}
+
+	esUrl, err := url.Parse(ds.URL)
+	if err != nil {
+		return err
+	}
+
+	resourcePath, err := url.Parse(req.Path)
+	if err != nil {
+		return err
+	}
+
+	// We take the path and the query-string only
+	esUrl.RawQuery = resourcePath.RawQuery
+	esUrl.Path = path.Join(esUrl.Path, resourcePath.Path)
+
+	request, err := http.NewRequestWithContext(ctx, req.Method, esUrl.String(), bytes.NewBuffer(req.Body))
+	if err != nil {
+		return err
+	}
+
+	response, err := ds.HTTPClient.Do(request)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		if err := response.Body.Close(); err != nil {
+			logger.Warn("Failed to close response body", "err", err)
+		}
+	}()
+
+	body, err := io.ReadAll(response.Body)
+	if err != nil {
+		return err
+	}
+
+	responseHeaders := map[string][]string{
+		"content-type": {"application/json"},
+	}
+
+	if response.Header.Get("Content-Encoding") != "" {
+		responseHeaders["content-encoding"] = []string{response.Header.Get("Content-Encoding")}
+	}
+
+	return sender.Send(&backend.CallResourceResponse{
+		Status:  response.StatusCode,
+		Headers: responseHeaders,
+		Body:    body,
+	})
+}

public/app/plugins/datasource/elasticsearch/datasource.test.ts

@@ -18,7 +18,7 @@ import {
   TimeRange,
   toUtc,
 } from '@grafana/data';
-import { BackendSrvRequest, FetchResponse, reportInteraction } from '@grafana/runtime';
+import { BackendSrvRequest, FetchResponse, reportInteraction, config } from '@grafana/runtime';
 import { backendSrv } from 'app/core/services/backend_srv'; // will use the version in __mocks__
 import { TimeSrv } from 'app/features/dashboard/services/TimeSrv';
 import { TemplateSrv } from 'app/features/templating/template_srv';
@@ -31,6 +31,8 @@ import { Filters, ElasticsearchOptions, ElasticsearchQuery } from './types';
 
 const ELASTICSEARCH_MOCK_URL = 'http://elasticsearch.local';
 
+const originalConsoleError = console.error;
+
 jest.mock('@grafana/runtime', () => ({
   ...jest.requireActual('@grafana/runtime'),
   getBackendSrv: () => backendSrv,
@@ -1291,3 +1293,37 @@ const logsResponse = {
     ],
   },
 };
+
+describe('ElasticDatasource using backend', () => {
+  beforeEach(() => {
+    console.error = jest.fn();
+    config.featureToggles.enableElasticsearchBackendQuerying = true;
+  });
+
+  afterEach(() => {
+    console.error = originalConsoleError;
+    config.featureToggles.enableElasticsearchBackendQuerying = false;
+  });
+  describe('getDatabaseVersion', () => {
+    it('should correctly get db version', async () => {
+      const { ds } = getTestContext();
+      ds.getResource = jest.fn().mockResolvedValue({ version: { number: '8.0.0' } });
+      const version = await ds.getDatabaseVersion();
+      expect(version?.raw).toBe('8.0.0');
+    });
+
+    it('should correctly return null if invalid numeric version', async () => {
+      const { ds } = getTestContext();
+      ds.getResource = jest.fn().mockResolvedValue({ version: { number: 8 } });
+      const version = await ds.getDatabaseVersion();
+      expect(version).toBe(null);
+    });
+
+    it('should correctly return null if rejected request', async () => {
+      const { ds } = getTestContext();
+      ds.getResource = jest.fn().mockRejectedValue({});
+      const version = await ds.getDatabaseVersion();
+      expect(version).toBe(null);
+    });
+  });
+});

public/app/plugins/datasource/elasticsearch/datasource.ts

@@ -1,5 +1,5 @@
 import { cloneDeep, find, first as _first, isObject, isString, map as _map } from 'lodash';
-import { generate, lastValueFrom, Observable, of } from 'rxjs';
+import { from, generate, lastValueFrom, Observable, of } from 'rxjs';
 import { catchError, first, map, mergeMap, skipWhile, throwIfEmpty, tap } from 'rxjs/operators';
 import { SemVer } from 'semver';
 
@@ -739,7 +739,11 @@ export class ElasticDatasource
 
   private getDatabaseVersionUncached(): Promise<SemVer | null> {
     // we want this function to never fail
-    return lastValueFrom(this.legacyQueryRunner.request('GET', '/')).then(
+    const getDbVersionObservable = config.featureToggles.enableElasticsearchBackendQuerying
+      ? from(this.getResource(''))
+      : this.legacyQueryRunner.request('GET', '/');
+
+    return lastValueFrom(getDbVersionObservable).then(
       (data) => {
         const versionNumber = data?.version?.number;
         if (typeof versionNumber !== 'string') {