[Backport 7.x] Added x-elastic-client-meta header (#1377)

Co-authored-by: Tomas Della Vedova <delvedor@users.noreply.github.com>

lib/Helpers.js

@@ -28,12 +28,14 @@ const { ResponseError, ConfigurationError } = require('./errors')
 const pImmediate = promisify(setImmediate)
 const sleep = promisify(setTimeout)
 const kClient = Symbol('elasticsearch-client')
+const kMetaHeader = Symbol('meta header')
 /* istanbul ignore next */
 const noop = () => {}
 
 class Helpers {
   constructor (opts) {
     this[kClient] = opts.client
+    this[kMetaHeader] = opts.metaHeader
     this.maxRetries = opts.maxRetries
   }
 
@@ -71,6 +73,10 @@ class Helpers {
    * @return {iterator} the async iterator
    */
   async * scrollSearch (params, options = {}) {
+    if (this[kMetaHeader] !== null) {
+      options.headers = options.headers || {}
+      options.headers['x-elastic-client-meta'] = this[kMetaHeader] + ',h=s'
+    }
     // TODO: study scroll search slices
     const wait = options.wait || 5000
     const maxRetries = options.maxRetries || this.maxRetries
@@ -99,7 +105,7 @@ class Helpers {
       stop = true
       await this[kClient].clearScroll(
         { body: { scroll_id } },
-        { ignore: [400] }
+        { ignore: [400], ...options }
       )
     }
 
@@ -414,6 +420,7 @@ class Helpers {
   bulk (options) {
     const client = this[kClient]
     const { serialize, deserialize } = client.serializer
+    const reqOptions = this[kMetaHeader] !== null ? { headers: { 'x-elastic-client-meta': this[kMetaHeader] + ',h=bp' } } : {}
     const {
       datasource,
       onDocument,
@@ -676,7 +683,7 @@ class Helpers {
 
       function tryBulk (bulkBody, callback) {
         if (shouldAbort === true) return callback(null, [])
-        client.bulk(Object.assign({}, bulkOptions, { body: bulkBody }), (err, { body }) => {
+        client.bulk(Object.assign({}, bulkOptions, { body: bulkBody }), reqOptions, (err, { body }) => {
           if (err) return callback(err, null)
           if (body.errors === false) {
             stats.successful += body.items.length