Implement ElasticSearch search engine

* Adding indexing, searching and default translator for ElasticSearch engine
* Modifying default backend to use ES if it is enabled
* Adding configuration schema to configure ElasticSearch 3 different ways
   * Elastic.co hosted solution
   * AWS hosted ElasticSearch Service
   * Custom, using standard ElasticSearch URL and auth info
* Add and modify some of the documentation regarding search

Signed-off-by: Jussi Hallila <jussi@hallila.com>

plugins/search-backend-node/src/IndexBuilder.ts

@@ -18,13 +18,13 @@ import {
   DocumentCollator,
   DocumentDecorator,
   IndexableDocument,
+  SearchEngine,
 } from '@backstage/search-common';
 import { Logger } from 'winston';
 import { Scheduler } from './index';
 import {
   RegisterCollatorParameters,
   RegisterDecoratorParameters,
-  SearchEngine,
 } from './types';
 
 interface CollatorEnvelope {

plugins/search-backend-node/src/engines/LunrSearchEngine.test.ts

@@ -16,7 +16,7 @@
 
 import { getVoidLogger } from '@backstage/backend-common';
 import lunr from 'lunr';
-import { SearchEngine } from '../types';
+import { SearchEngine } from '@backstage/search-common';
 import { ConcreteLunrQuery, LunrSearchEngine } from './LunrSearchEngine';
 
 /**

plugins/search-backend-node/src/engines/LunrSearchEngine.ts

@@ -18,10 +18,11 @@ import {
   IndexableDocument,
   SearchQuery,
   SearchResultSet,
+  QueryTranslator,
+  SearchEngine,
 } from '@backstage/search-common';
 import lunr from 'lunr';
 import { Logger } from 'winston';
-import { QueryTranslator, SearchEngine } from '../types';
 
 export type ConcreteLunrQuery = {
   lunrQueryBuilder: lunr.Index.QueryBuilder;

plugins/search-backend-node/src/index.ts

@@ -17,4 +17,8 @@
 export { IndexBuilder } from './IndexBuilder';
 export { Scheduler } from './Scheduler';
 export { LunrSearchEngine } from './engines';
-export type { SearchEngine } from './types';
+
+/**
+ * @deprecated Import from @backstage/search-common instead
+ */
+export type { SearchEngine } from '@backstage/search-common';

plugins/search-backend-node/src/types.ts

@@ -14,13 +14,7 @@
  * limitations under the License.
  */
 
-import {
-  DocumentCollator,
-  DocumentDecorator,
-  IndexableDocument,
-  SearchQuery,
-  SearchResultSet,
-} from '@backstage/search-common';
+import { DocumentCollator, DocumentDecorator } from '@backstage/search-common';
 
 /**
  * Parameters required to register a collator.
@@ -46,31 +40,3 @@ export interface RegisterDecoratorParameters {
    */
   decorator: DocumentDecorator;
 }
-
-/**
- * A type of function responsible for translating an abstract search query into
- * a concrete query relevant to a particular search engine.
- */
-export type QueryTranslator = (query: SearchQuery) => unknown;
-
-/**
- * Interface that must be implemented by specific search engines, responsible
- * for performing indexing and querying and translating abstract queries into
- * concrete, search engine-specific queries.
- */
-export interface SearchEngine {
-  /**
-   * Override the default translator provided by the SearchEngine.
-   */
-  setTranslator(translator: QueryTranslator): void;
-
-  /**
-   * Add the given documents to the SearchEngine index of the given type.
-   */
-  index(type: string, documents: IndexableDocument[]): Promise<void>;
-
-  /**
-   * Perform a search query against the SearchEngine.
-   */
-  query(query: SearchQuery): Promise<SearchResultSet>;
-}