Relax error requirement of ECONNREFUSED (#63835) (#63851)

Also added a test for the different errors that could occur
at a lower network level.

src/plugins/console/server/__tests__/proxy_route/proxy_fallback.test.ts

@@ -0,0 +1,64 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { duration } from 'moment';
+import { getProxyRouteHandlerDeps } from './mocks';
+
+import { kibanaResponseFactory } from '../../../../../core/server';
+import { createHandler } from '../../routes/api/console/proxy/create_handler';
+import * as requestModule from '../../lib/proxy_request';
+
+describe('Console Proxy Route', () => {
+  afterEach(async () => {
+    jest.resetAllMocks();
+  });
+
+  describe('fallback behaviour', () => {
+    it('falls back to all configured endpoints regardless of error', async () => {
+      // Describe a situation where all three configured nodes reject
+      (requestModule.proxyRequest as jest.Mock).mockRejectedValueOnce(new Error('ECONNREFUSED'));
+      (requestModule.proxyRequest as jest.Mock).mockRejectedValueOnce(new Error('EHOSTUNREACH'));
+      (requestModule.proxyRequest as jest.Mock).mockRejectedValueOnce(new Error('ESOCKETTIMEDOUT'));
+
+      const handler = createHandler(
+        getProxyRouteHandlerDeps({
+          readLegacyESConfig: () => ({
+            requestTimeout: duration(30000),
+            customHeaders: {},
+            requestHeadersWhitelist: [],
+            hosts: ['http://localhost:9201', 'http://localhost:9202', 'http://localhost:9203'],
+          }),
+        })
+      );
+
+      const response = await handler(
+        {} as any,
+        {
+          headers: {},
+          query: { method: 'get', path: 'test' },
+        } as any,
+        kibanaResponseFactory
+      );
+
+      expect(response.status).toBe(502);
+      // Return the message from the ES node we attempted last.
+      expect(response.payload.message).toBe('ESOCKETTIMEDOUT');
+    });
+  });
+});

src/plugins/console/server/routes/api/console/proxy/create_handler.ts

@@ -175,10 +175,9 @@ export const createHandler = ({
 
       break;
     } catch (e) {
+      // If we reached here it means we hit a lower level network issue than just, for e.g., a 500.
+      // We try contacting another node in that case.
       log.error(e);
-      if (e.code !== 'ECONNREFUSED') {
-        return response.internalError(e);
-      }
       if (idx === hosts.length - 1) {
         log.warn(`Could not connect to any configured ES node [${hosts.join(', ')}]`);
         return response.customError({