add support for global fetch (#3258)

Author: rochdev

.github/workflows/plugins.yml

@@ -332,6 +332,23 @@ jobs:
         uses: ./.github/actions/testagent/logs
       - uses: codecov/codecov-action@v2
 
+  fetch:
+    runs-on: ubuntu-latest
+    env:
+      PLUGINS: fetch
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ./.github/actions/testagent/start
+      - uses: ./.github/actions/node/setup
+      - run: yarn install
+      - uses: ./.github/actions/node/oldest
+      - run: yarn test:plugins:ci
+      - uses: ./.github/actions/node/latest
+      - run: yarn test:plugins:ci
+      - if: always()
+        uses: ./.github/actions/testagent/logs
+      - uses: codecov/codecov-action@v2
+
   generic-pool:
     runs-on: ubuntu-latest
     env:

docs/API.md

@@ -40,6 +40,7 @@ tracer.use('pg', {
 <h5 id="generic-pool"></h5>
 <h5 id="google-cloud-pubsub"></h5>
 <h5 id="fastify"></h5>
+<h5 id="fetch"></h5>
 <h5 id="graphql"></h5>
 <h5 id="graphql-tags"></h5>
 <h5 id="graphql-config"></h5>
@@ -110,6 +111,7 @@ tracer.use('pg', {
 * [elasticsearch](./interfaces/plugins.elasticsearch.html)
 * [express](./interfaces/plugins.express.html)
 * [fastify](./interfaces/plugins.fastify.html)
+* [fetch](./interfaces/plugins.fetch.html)
 * [generic-pool](./interfaces/plugins.generic_pool.html)
 * [google-cloud-pubsub](./interfaces/plugins.google_cloud_pubsub.html)
 * [graphql](./interfaces/plugins.graphql.html)

docs/test.ts

@@ -248,6 +248,8 @@ tracer.use('express');
 tracer.use('express', httpServerOptions);
 tracer.use('fastify');
 tracer.use('fastify', httpServerOptions);
+tracer.use('fetch');
+tracer.use('fetch', httpClientOptions);
 tracer.use('generic-pool');
 tracer.use('google-cloud-pubsub');
 tracer.use('graphql');

index.d.ts

@@ -749,6 +749,7 @@ interface Plugins {
   "elasticsearch": plugins.elasticsearch;
   "express": plugins.express;
   "fastify": plugins.fastify;
+  "fetch": plugins.fetch;
   "generic-pool": plugins.generic_pool;
   "google-cloud-pubsub": plugins.google_cloud_pubsub;
   "graphql": plugins.graphql;
@@ -1092,6 +1093,12 @@ declare namespace plugins {
    */
   interface fastify extends HttpServer {}
 
+  /**
+   * This plugin automatically instruments the
+   * [fetch](https://nodejs.org/api/globals.html#fetch) global.
+   */
+  interface fetch extends HttpClient {}
+
   /**
    * This plugin patches the [generic-pool](https://github.com/coopernurse/node-pool)
    * module to bind the callbacks the the caller context.

packages/datadog-instrumentations/src/fetch.js

@@ -0,0 +1,48 @@
+'use strict'
+
+const shimmer = require('../../datadog-shimmer')
+const { channel } = require('./helpers/instrument')
+
+const startChannel = channel('apm:fetch:request:start')
+const finishChannel = channel('apm:fetch:request:finish')
+const errorChannel = channel('apm:fetch:request:error')
+
+function wrapFetch (fetch, Request) {
+  if (typeof fetch !== 'function') return fetch
+
+  return function (input, init) {
+    if (!startChannel.hasSubscribers) return fetch.apply(this, arguments)
+
+    const req = new Request(input, init)
+    const headers = req.headers
+    const message = { req, headers }
+
+    startChannel.publish(message)
+
+    // Request object is read-only so we need new objects to change headers.
+    arguments[0] = message.req
+    arguments[1] = { headers: message.headers }
+
+    return fetch.apply(this, arguments)
+      .then(
+        res => {
+          finishChannel.publish({ req, res })
+
+          return res
+        },
+        err => {
+          if (err.name !== 'AbortError') {
+            errorChannel.publish(err)
+          }
+
+          finishChannel.publish({ req })
+
+          throw err
+        }
+      )
+  }
+}
+
+if (globalThis.fetch) {
+  globalThis.fetch = shimmer.wrap(fetch, wrapFetch(fetch, globalThis.Request))
+}

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

@@ -19,6 +19,9 @@ const disabledInstrumentations = new Set(
 
 const loadChannel = channel('dd-trace:instrumentation:load')
 
+// Globals
+require('../fetch')
+
 // TODO: make this more efficient
 
 for (const packageName of names) {

packages/datadog-plugin-fetch/src/index.js

@@ -0,0 +1,36 @@
+'use strict'
+
+const HttpClientPlugin = require('../../datadog-plugin-http/src/client')
+const { HTTP_HEADERS } = require('../../../ext/formats')
+
+class FetchPlugin extends HttpClientPlugin {
+  static get id () { return 'fetch' }
+
+  addTraceSub (eventName, handler) {
+    this.addSub(`apm:${this.constructor.id}:${this.operation}:${eventName}`, handler)
+  }
+
+  start (message) {
+    const req = message.req
+    const options = new URL(req.url)
+    const headers = options.headers = Object.fromEntries(req.headers.entries())
+
+    const args = { options }
+
+    super.start({ args })
+
+    message.req = new globalThis.Request(req, { headers })
+  }
+
+  _inject (span, headers) {
+    const carrier = {}
+
+    this.tracer.inject(span, HTTP_HEADERS, carrier)
+
+    for (const name in carrier) {
+      headers.append(name, carrier[name])
+    }
+  }
+}
+
+module.exports = FetchPlugin