fix: elastic search for missing or no indexes

this occurs when the index is missing during the search for example the
TechDocs provider creates the index when initiating, but if there's no
docs to index, it removes the index but still tries to search from it.

fixes #16423

Signed-off-by: Heikki Hellgren <heikki.hellgren@op.fi>

.changeset/shaggy-crews-carry.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-search-backend-module-elasticsearch': patch
+---
+
+fix ElasticSearch throwing error when index is missing

plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchClientWrapper.test.ts

@@ -119,7 +119,12 @@ describe('ElasticSearchClientWrapper', () => {
     it('search', async () => {
       const wrapper = ElasticSearchClientWrapper.fromClientOptions(esOptions);
 
-      const searchInput = { index: 'xyz', body: { eg: 'etc' } };
+      const searchInput = {
+        index: 'xyz',
+        body: { eg: 'etc' },
+        ignore_unavailable: true,
+        allow_no_indices: true,
+      };
       const result = (await wrapper.search(searchInput)) as any;
 
       // Should call the ElasticSearch client's search with expected input.
@@ -241,7 +246,12 @@ describe('ElasticSearchClientWrapper', () => {
     it('search', async () => {
       const wrapper = ElasticSearchClientWrapper.fromClientOptions(osOptions);
 
-      const searchInput = { index: 'xyz', body: { eg: 'etc' } };
+      const searchInput = {
+        index: 'xyz',
+        body: { eg: 'etc' },
+        ignore_unavailable: true,
+        allow_no_indices: true,
+      };
       const result = (await wrapper.search(searchInput)) as any;
 
       // Should call the OpenSearch client's search with expected input.
@@ -350,7 +360,12 @@ describe('ElasticSearchClientWrapper', () => {
       const wrapper = ElasticSearchClientWrapper.fromClientOptions(osOptions);
       expect(OpenSearchClient).toHaveBeenCalledWith(osOptions);
 
-      const searchInput = { index: 'xyz', body: { eg: 'etc' } };
+      const searchInput = {
+        index: 'xyz',
+        body: { eg: 'etc' },
+        ignore_unavailable: true,
+        allow_no_indices: true,
+      };
       const result = (await wrapper.search(searchInput)) as any;
       expect(result.client).toBe('os');
       expect(result.args).toStrictEqual(searchInput);

plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchClientWrapper.ts

@@ -91,12 +91,23 @@ export class ElasticSearchClientWrapper {
   }
 
   search(options: { index: string | string[]; body: Object }) {
+    const searchOptions = {
+      ignore_unavailable: true,
+      allow_no_indices: true,
+    };
+
     if (this.openSearchClient) {
-      return this.openSearchClient.search(options);
+      return this.openSearchClient.search({
+        ...options,
+        ...searchOptions,
+      });
     }
 
     if (this.elasticSearchClient) {
-      return this.elasticSearchClient.search(options);
+      return this.elasticSearchClient.search({
+        ...options,
+        ...searchOptions,
+      });
     }
 
     throw new Error('No client defined');