X-Opaque-Id support (#997)

* Added X-Opaque-Id support

* Updated type definitions

* Updated test

* Updated docs

Author: delvedor

docs/configuration.asciidoc

@@ -173,6 +173,11 @@ function generateRequestId (params, options) {
 |`string` - The name to identify the client instance in the events. +
 _Default:_ `elasticsearch-js`
 
+|`opaqueIdPrefix`
+|`string` - A string that will be use to prefix any `X-Opaque-Id` header. +
+See https://www.elastic.co/guide/en/elasticsearch/client/javascript-api/current/observability.html#_x-opaque-id_support[`X-Opaque-Id` support] for more details. +
+_Default:_ `null`
+
 |`headers`
 |`object` - A set of custom headers to send in every request. +
 _Default:_ `{}`

docs/observability.asciidoc

@@ -248,3 +248,46 @@ child.search({
   if (err) console.log(err)
 })
 ----
+
+=== X-Opaque-Id support
+To improve the overall observability, the client offers an easy way to configure the `X-Opaque-Id` header. If you set the `X-Opaque-Id` in a specific request, this will allow you to discover this identifier in the https://www.elastic.co/guide/en/elasticsearch/reference/master/logging.html#deprecation-logging[deprecation logs], help you with https://www.elastic.co/guide/en/elasticsearch/reference/master/index-modules-slowlog.html#_identifying_search_slow_log_origin[identifying search slow log origin] as well as https://www.elastic.co/guide/en/elasticsearch/reference/master/tasks.html#_identifying_running_tasks[identifying running tasks].
+
+The `X-Opaque-Id` should be configured in each request, for doing that you can use the `opaqueId` option, as you can see in the following example. +
+The resulting header will be `{ 'X-Opaque-Id': 'my-search' }`.
+
+[source,js]
+----
+const { Client } = require('@elastic/elasticsearch')
+const client = new Client({
+  node: 'http://localhost:9200'
+})
+
+client.search({
+  index: 'my-index',
+  body: { foo: 'bar' }
+}, {
+  opaqueId: 'my-search'
+}, (err, result) => {
+  if (err) console.log(err)
+})
+----
+
+Sometimes it may be useful to prefix all the `X-Opaque-Id` headers with a specific string, in case you need to identify a specific client or server. For doing this, the client offers a top-level configuration option: `opaqueIdPrefix`. +
+In the following example, the resulting header will be `{ 'X-Opaque-Id': 'proxy-client::my-search' }`.
+[source,js]
+----
+const { Client } = require('@elastic/elasticsearch')
+const client = new Client({
+  node: 'http://localhost:9200',
+  opaqueIdPrefix: 'proxy-client::'
+})
+
+client.search({
+  index: 'my-index',
+  body: { foo: 'bar' }
+}, {
+  opaqueId: 'my-search'
+}, (err, result) => {
+  if (err) console.log(err)
+})
+----

index.d.ts

@@ -94,6 +94,7 @@ interface ClientOptions {
   nodeFilter?: nodeFilterFn;
   nodeSelector?: nodeSelectorFn | string;
   headers?: anyObject;
+  opaqueIdPrefix?: string;
   generateRequestId?: generateRequestIdFn;
   name?: string;
   auth?: BasicAuth | ApiKeyAuth;

index.js

@@ -79,7 +79,8 @@ class Client extends EventEmitter {
       nodeSelector: 'round-robin',
       generateRequestId: null,
       name: 'elasticsearch-js',
-      auth: null
+      auth: null,
+      opaqueIdPrefix: null
     }, opts)
 
     this[kInitialOptions] = options
@@ -121,7 +122,8 @@ class Client extends EventEmitter {
       nodeFilter: options.nodeFilter,
       nodeSelector: options.nodeSelector,
       generateRequestId: options.generateRequestId,
-      name: options.name
+      name: options.name,
+      opaqueIdPrefix: options.opaqueIdPrefix
     })
 
     const apis = buildApi({

lib/Transport.d.ts

@@ -38,6 +38,7 @@ interface TransportOptions {
   headers?: anyObject;
   generateRequestId?: generateRequestIdFn;
   name: string;
+  opaqueIdPrefix?: string;
 }
 
 export interface RequestEvent<T = any, C = any> {
@@ -90,6 +91,7 @@ export interface TransportRequestOptions {
   id?: any;
   context?: any;
   warnings?: [string];
+  opaqueId?: string;
 }
 
 export interface TransportRequestCallback {
@@ -121,6 +123,7 @@ export default class Transport {
   compression: 'gzip' | false;
   sniffInterval: number;
   sniffOnConnectionFault: boolean;
+  opaqueIdPrefix: string | null;
   sniffEndpoint: string;
   _sniffEnabled: boolean;
   _nextSniff: number;

lib/Transport.js

@@ -41,6 +41,7 @@ class Transport {
     this.sniffEndpoint = opts.sniffEndpoint
     this.generateRequestId = opts.generateRequestId || generateRequestId()
     this.name = opts.name
+    this.opaqueIdPrefix = opts.opaqueIdPrefix
 
     this.nodeFilter = opts.nodeFilter || defaultNodeFilter
     if (typeof opts.nodeSelector === 'function') {
@@ -114,6 +115,12 @@ class Transport {
       // TODO: make this assignment FAST
       const headers = Object.assign({}, this.headers, options.headers)
 
+      if (options.opaqueId !== undefined) {
+        headers['X-Opaque-Id'] = this.opaqueIdPrefix !== null
+          ? this.opaqueIdPrefix + options.opaqueId
+          : options.opaqueId
+      }
+
       // handle json body
       if (params.body != null) {
         if (shouldSerialize(params.body) === true) {

test/unit/client.test.js

@@ -851,3 +851,87 @@ test('Elastic cloud config', t => {
 
   t.end()
 })
+
+test('Opaque Id support', t => {
+  t.test('No opaqueId', t => {
+    t.plan(3)
+
+    function handler (req, res) {
+      t.strictEqual(req.headers['x-opaque-id'], undefined)
+      res.setHeader('Content-Type', 'application/json;utf=8')
+      res.end(JSON.stringify({ hello: 'world' }))
+    }
+
+    buildServer(handler, ({ port }, server) => {
+      const client = new Client({
+        node: `http://localhost:${port}`
+      })
+
+      client.search({
+        index: 'test',
+        q: 'foo:bar'
+      }, (err, { body }) => {
+        t.error(err)
+        t.deepEqual(body, { hello: 'world' })
+        server.stop()
+      })
+    })
+  })
+
+  t.test('No prefix', t => {
+    t.plan(3)
+
+    function handler (req, res) {
+      t.strictEqual(req.headers['x-opaque-id'], 'bar')
+      res.setHeader('Content-Type', 'application/json;utf=8')
+      res.end(JSON.stringify({ hello: 'world' }))
+    }
+
+    buildServer(handler, ({ port }, server) => {
+      const client = new Client({
+        node: `http://localhost:${port}`
+      })
+
+      client.search({
+        index: 'test',
+        q: 'foo:bar'
+      }, {
+        opaqueId: 'bar'
+      }, (err, { body }) => {
+        t.error(err)
+        t.deepEqual(body, { hello: 'world' })
+        server.stop()
+      })
+    })
+  })
+
+  t.test('With prefix', t => {
+    t.plan(3)
+
+    function handler (req, res) {
+      t.strictEqual(req.headers['x-opaque-id'], 'foo-bar')
+      res.setHeader('Content-Type', 'application/json;utf=8')
+      res.end(JSON.stringify({ hello: 'world' }))
+    }
+
+    buildServer(handler, ({ port }, server) => {
+      const client = new Client({
+        node: `http://localhost:${port}`,
+        opaqueIdPrefix: 'foo-'
+      })
+
+      client.search({
+        index: 'test',
+        q: 'foo:bar'
+      }, {
+        opaqueId: 'bar'
+      }, (err, { body }) => {
+        t.error(err)
+        t.deepEqual(body, { hello: 'world' })
+        server.stop()
+      })
+    })
+  })
+
+  t.end()
+})