pre-8.0 improvements (#1567)

src/sniffingTransport.ts

@@ -0,0 +1,54 @@
+/*
+ * 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 assert from 'assert'
+import { Transport, SniffOptions } from '@elastic/transport'
+
+export default class SniffingTransport extends Transport {
+  sniff (opts: SniffOptions): void {
+    if (this.isSniffing) return
+    this.isSniffing = true
+
+    const request = {
+      method: 'GET',
+      path: this.sniffEndpoint ?? '/_nodes/_all/http'
+    }
+
+    this.request(request, { id: opts.requestId, meta: true })
+      .then(result => {
+        assert(isObject(result.body), 'The body should be an object')
+        this.isSniffing = false
+        const protocol = result.meta.connection?.url.protocol ?? /* istanbul ignore next */ 'http:'
+        const hosts = this.connectionPool.nodesToHost(result.body.nodes, protocol)
+        this.connectionPool.update(hosts)
+
+        result.meta.sniff = { hosts, reason: opts.reason }
+        this.diagnostic.emit('sniff', null, result)
+      })
+      .catch(err => {
+        this.isSniffing = false
+        err.meta.sniff = { hosts: [], reason: opts.reason }
+        this.diagnostic.emit('sniff', err, null)
+      })
+  }
+}
+
+function isObject (obj: any): obj is Record<string, any> {
+  return typeof obj === 'object'
+}