only load fetch plugin when fetch is used (#5272)

Author: rochdev

packages/datadog-instrumentations/src/fetch.js

@@ -1,12 +1,14 @@
 'use strict'
 
 const shimmer = require('../../datadog-shimmer')
-const { tracingChannel } = require('dc-polyfill')
+const { channel, tracingChannel } = require('dc-polyfill')
 const { createWrapFetch } = require('./helpers/fetch')
 
 if (globalThis.fetch) {
   const ch = tracingChannel('apm:fetch:request')
-  const wrapFetch = createWrapFetch(globalThis.Request, ch)
+  const wrapFetch = createWrapFetch(globalThis.Request, ch, () => {
+    channel('dd-trace:instrumentation:load').publish({ name: 'fetch' })
+  })
 
   globalThis.fetch = shimmer.wrapFunction(fetch, fetch => wrapFetch(fetch))
 }

packages/datadog-instrumentations/src/helpers/fetch.js

@@ -1,10 +1,15 @@
 'use strict'
 
-exports.createWrapFetch = function createWrapFetch (Request, ch) {
+exports.createWrapFetch = function createWrapFetch (Request, ch, onLoad) {
   return function wrapFetch (fetch) {
     if (typeof fetch !== 'function') return fetch
 
     return function (input, init) {
+      if (onLoad) {
+        onLoad()
+        onLoad = undefined
+      }
+
       if (!ch.start.hasSubscribers) return fetch.apply(this, arguments)
 
       if (input instanceof Request) {

packages/dd-trace/src/plugin_manager.js

@@ -28,9 +28,6 @@ loadChannel.subscribe(({ name }) => {
   maybeEnable(plugins[name])
 })
 
-// Globals
-maybeEnable(require('../../datadog-plugin-fetch/src'))
-
 // Always enabled
 maybeEnable(require('../../datadog-plugin-dd-trace-api/src'))
 
@@ -106,6 +103,10 @@ module.exports = class PluginManager {
     this._tracerConfig = config
     this._tracer._nomenclature.configure(config)
 
+    if (!config._isInServerlessEnvironment?.()) {
+      maybeEnable(require('../../datadog-plugin-fetch/src'))
+    }
+
     for (const name in pluginClasses) {
       this.loadPlugin(name)
     }