Elasticsearch: Add word highlighting to search results (#30293)

* Elasticsearch: Add word highlighting to logs

* Remove unused deps; refactor matching code to remove matchAll

* Adding searchWords test

* Adding two matches for highlighting

* Adding code comments

* formatting comments

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

@@ -18,6 +18,8 @@ import {
 import { describeMetric } from './utils';
 import { metricAggregationConfig } from './components/QueryEditor/MetricAggregationsEditor/utils';
 
+const HIGHLIGHT_TAGS_EXP = `${queryDef.highlightTags.pre}([^@]+)${queryDef.highlightTags.post}`;
+
 export class ElasticResponse {
   constructor(private targets: ElasticsearchQuery[], private response: any) {
     this.targets = targets;
@@ -373,6 +375,7 @@ export class ElasticResponse {
         _type: hit._type,
         _index: hit._index,
         sort: hit.sort,
+        highlight: hit.highlight,
       };
 
       if (hit._source) {
@@ -438,7 +441,6 @@ export class ElasticResponse {
     logLevelField?: string
   ): DataQueryResponse {
     const dataFrame: DataFrame[] = [];
-
     for (let n = 0; n < this.response.responses.length; n++) {
       const response = this.response.responses[n];
       if (response.error) {
@@ -459,11 +461,41 @@ export class ElasticResponse {
           // Add a row for each document
           for (const doc of docs) {
             if (logLevelField) {
-              // Remap level field based on the datasource config. This field is then used in explore to figure out the
-              // log level. We may rewrite some actual data in the level field if they are different.
+              // Remap level field based on the datasource config. This field is
+              // then used in explore to figure out the log level. We may rewrite
+              // some actual data in the level field if they are different.
               doc['level'] = doc[logLevelField];
             }
-
+            // When highlighting exists, we need to collect all the highlighted
+            // phrases and add them to the DataFrame's meta.searchWords array.
+            if (doc.highlight) {
+              // There might be multiple words so we need two versions of the
+              // regular expression. One to match gobally, when used with part.match,
+              // it returns and array of matches. The second one is used to capture the
+              // values between the tags.
+              const globalHighlightWordRegex = new RegExp(HIGHLIGHT_TAGS_EXP, 'g');
+              const highlightWordRegex = new RegExp(HIGHLIGHT_TAGS_EXP);
+              const newSearchWords = Object.keys(doc.highlight)
+                .flatMap((key) => {
+                  return doc.highlight[key].flatMap((line: string) => {
+                    const matchedPhrases = line.match(globalHighlightWordRegex);
+                    if (!matchedPhrases) {
+                      return [];
+                    }
+                    return matchedPhrases.map((part) => {
+                      const matches = part.match(highlightWordRegex);
+                      return (matches && matches[1]) || null;
+                    });
+                  });
+                })
+                .filter(_.identity);
+              // If meta and searchWords already exists, add the words and
+              // deduplicate otherwise create a new set of search words.
+              const searchWords = series.meta?.searchWords
+                ? _.uniq([...series.meta.searchWords, ...newSearchWords])
+                : [...newSearchWords];
+              series.meta = series.meta ? { ...series.meta, searchWords } : { searchWords };
+            }
             series.add(doc);
           }
           if (isLogsRequest) {
@@ -554,6 +586,7 @@ type Doc = {
   _index: string;
   _source?: any;
   sort?: Array<string | number>;
+  highlight?: Record<string, string[]>;
 };
 
 /**
@@ -575,6 +608,7 @@ const flattenHits = (hits: Doc[]): { docs: Array<Record<string, any>>; propNames
       _type: hit._type,
       _index: hit._index,
       sort: hit.sort,
+      highlight: hit.highlight,
       _source: { ...flattened },
       ...flattened,
     };

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

@@ -10,7 +10,7 @@ import {
   isPipelineAggregation,
   isPipelineAggregationWithMultipleBucketPaths,
 } from './components/QueryEditor/MetricAggregationsEditor/aggregations';
-import { defaultBucketAgg, defaultMetricAgg, findMetricById } from './query_def';
+import { defaultBucketAgg, defaultMetricAgg, findMetricById, highlightTags } from './query_def';
 import { ElasticsearchQuery } from './types';
 import { convertOrderByToMetricId } from './utils';
 
@@ -436,6 +436,14 @@ export class ElasticQueryBuilder {
     return {
       ...query,
       aggs: this.build(target, null, querystring).aggs,
+      highlight: {
+        fields: {
+          '*': {},
+        },
+        pre_tags: [highlightTags.pre],
+        post_tags: [highlightTags.post],
+        fragment_size: 2147483647,
+      },
     };
   }
 }

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

@@ -26,6 +26,11 @@ export const movingAvgModelOptions: MovingAverageModelOption[] = [
   { label: 'Holt Winters', value: 'holt_winters' },
 ];
 
+export const highlightTags = {
+  pre: '@HIGHLIGHT@',
+  post: '@/HIGHLIGHT@',
+};
+
 export function defaultMetricAgg(id = '1'): MetricAggregation {
   return { type: 'count', id };
 }

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

@@ -2,6 +2,7 @@ import { DataFrameView, FieldCache, KeyValue, MutableDataFrame } from '@grafana/
 import { ElasticResponse } from '../elastic_response';
 import flatten from 'app/core/utils/flatten';
 import { ElasticsearchQuery } from '../types';
+import { highlightTags } from '../query_def';
 
 describe('ElasticResponse', () => {
   let targets: ElasticsearchQuery[];
@@ -1218,7 +1219,7 @@ describe('ElasticResponse', () => {
         key: 'Q-1561369883389-0.7611823271062786-0',
         liveStreaming: false,
         maxDataPoints: 1620,
-        query: '',
+        query: 'hello AND message',
         timeField: '@timestamp',
       },
     ];
@@ -1254,6 +1255,11 @@ describe('ElasticResponse', () => {
                     lvl: 'debug',
                   },
                 },
+                highlight: {
+                  message: [
+                    `${highlightTags.pre}hello${highlightTags.post}, i am a ${highlightTags.pre}message${highlightTags.post}`,
+                  ],
+                },
               },
               {
                 _id: 'kdospaidopa',
@@ -1268,6 +1274,11 @@ describe('ElasticResponse', () => {
                     lvl: 'info',
                   },
                 },
+                highlight: {
+                  message: [
+                    `${highlightTags.pre}hello${highlightTags.post}, i am a ${highlightTags.pre}message${highlightTags.post}`,
+                  ],
+                },
               },
             ],
           },
@@ -1279,6 +1290,12 @@ describe('ElasticResponse', () => {
       const result = new ElasticResponse(targets, response).getLogs();
       expect(result.data.length).toBe(2);
       const logResults = result.data[0] as MutableDataFrame;
+      expect(logResults).toHaveProperty('meta');
+      expect(logResults.meta).toEqual({
+        searchWords: ['hello', 'message'],
+        preferredVisualisationType: 'logs',
+      });
+
       const fields = logResults.fields.map((f) => {
         return {
           name: f.name,