[file upload] use index exists API for /internal/file_upload/index_exists route (#98471)

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

x-pack/plugins/file_upload/server/routes.ts

@@ -185,7 +185,7 @@ export function fileUploadRoutes(coreSetup: CoreSetup<StartDeps, unknown>, logge
   /**
    * @apiGroup FileDataVisualizer
    *
-   * @api {post} /internal/file_upload/index_exists ES Field caps wrapper checks if index exists
+   * @api {post} /internal/file_upload/index_exists ES indices exists wrapper checks if index exists
    * @apiName IndexExists
    */
   router.post(
@@ -200,20 +200,10 @@ export function fileUploadRoutes(coreSetup: CoreSetup<StartDeps, unknown>, logge
     },
     async (context, request, response) => {
       try {
-        const { index } = request.body;
-
-        const options = {
-          index: [index],
-          fields: ['*'],
-          ignore_unavailable: true,
-          allow_no_indices: true,
-        };
-
-        const { body } = await context.core.elasticsearch.client.asCurrentUser.fieldCaps(options);
-        const exists = Array.isArray(body.indices) && body.indices.length !== 0;
-        return response.ok({
-          body: { exists },
-        });
+        const {
+          body: indexExists,
+        } = await context.core.elasticsearch.client.asCurrentUser.indices.exists(request.body);
+        return response.ok({ body: { exists: indexExists } });
       } catch (e) {
         return response.customError(wrapError(e));
       }

x-pack/test/api_integration/apis/file_upload/index.ts

@@ -10,5 +10,6 @@ import { FtrProviderContext } from '../../ftr_provider_context';
 export default function ({ loadTestFile }: FtrProviderContext) {
   describe('File upload', function () {
     loadTestFile(require.resolve('./has_import_permission'));
+    loadTestFile(require.resolve('./index_exists'));
   });
 }

x-pack/test/api_integration/apis/file_upload/index_exists.ts

@@ -0,0 +1,48 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import expect from '@kbn/expect';
+import { FtrProviderContext } from '../../ftr_provider_context';
+
+export default ({ getService }: FtrProviderContext) => {
+  const esArchiver = getService('esArchiver');
+  const supertest = getService('supertest');
+
+  describe('POST /internal/file_upload/index_exists', () => {
+    before(async () => {
+      await esArchiver.loadIfNeeded('logstash_functional');
+    });
+
+    after(async () => {
+      await esArchiver.unload('logstash_functional');
+    });
+
+    it('should return true when index exists', async () => {
+      const resp = await supertest
+        .post(`/internal/file_upload/index_exists`)
+        .set('kbn-xsrf', 'kibana')
+        .send({
+          index: 'logstash-2015.09.22',
+        })
+        .expect(200);
+
+      expect(resp.body.exists).to.be(true);
+    });
+
+    it('should return false when index does not exists', async () => {
+      const resp = await supertest
+        .post(`/internal/file_upload/index_exists`)
+        .set('kbn-xsrf', 'kibana')
+        .send({
+          index: 'myNewIndex',
+        })
+        .expect(200);
+
+      expect(resp.body.exists).to.be(false);
+    });
+  });
+};