esbuild: graceful continue when bundling dead code (#3215)

- previously, when encountering a dead code path that requires a not-installed instrumented package, build would fail
  - this would happen when, say, `knex` requires the `tedious` library for an app that is only making use of `pg`
  - without `dd-trace/esbuild`, a user simply adds `tedious` to their `external` list and goes on with their day
  - or in other words, vanilla esbuild doesn't really care when it encounters these missing modules
  - with `dd-trace/esbuild`, we would throw an error and the build fails
- one solution would be to not instrument external packages but many users expect this behavior to work
  - in fact, we've been telling users to do just this before we supported a plugin
- now, with this change, the `require('unused-module')` call remains in the output code
  - print a warning when this happens (at build time), regardless of debug level, since it might not be intentional

Author: tlhunter

LICENSE-3rdparty.csv

@@ -51,6 +51,7 @@ dev,glob,ISC,Copyright Isaac Z. Schlueter and Contributors
 dev,graphql,MIT,Copyright 2015 Facebook Inc.
 dev,int64-buffer,MIT,Copyright 2015-2016 Yusuke Kawasaki
 dev,jszip,MIT,Copyright 2015-2016 Stuart Knightley and contributors
+dev,knex,MIT,Copyright (c) 2013-present Tim Griesser
 dev,mkdirp,MIT,Copyright 2010 James Halliday
 dev,mocha,MIT,Copyright 2011-2018 JS Foundation and contributors https://js.foundation
 dev,multer,MIT,Copyright 2014 Hage Yaapa

integration-tests/esbuild/basic-test.js

@@ -11,6 +11,7 @@ const tracer = require('../../').init() // dd-trace
 const assert = require('assert')
 const express = require('express')
 const http = require('http')
+require('knex') // has dead code paths for multiple instrumented packages
 
 const app = express()
 const PORT = 31415

integration-tests/esbuild/build.js

@@ -9,7 +9,18 @@ esbuild.build({
   outfile: 'out.js',
   plugins: [ddPlugin],
   platform: 'node',
-  target: ['node16']
+  target: ['node16'],
+  external: [
+    // dead code paths introduced by knex
+    'pg',
+    'mysql2',
+    'better-sqlite3',
+    'sqlite3',
+    'mysql',
+    'oracledb',
+    'pg-query-stream',
+    'tedious'
+  ]
 }).catch((err) => {
   console.error(err) // eslint-disable-line no-console
   process.exit(1)

integration-tests/esbuild/package.json

@@ -19,6 +19,7 @@
   "license": "ISC",
   "dependencies": {
     "esbuild": "0.16.12",
-    "express": "^4.16.2"
+    "express": "^4.16.2",
+    "knex": "^2.4.2"
   }
 }

package.json

@@ -120,6 +120,7 @@
     "graphql": "0.13.2",
     "int64-buffer": "^0.1.9",
     "jszip": "^3.5.0",
+    "knex": "^2.4.2",
     "mkdirp": "^0.5.1",
     "mocha": "8",
     "msgpack-lite": "^0.1.26",

packages/datadog-esbuild/index.js

@@ -39,7 +39,19 @@ module.exports.setup = function (build) {
 
     if (args.namespace === 'file' && packagesOfInterest.has(packageName)) {
       // The file namespace is used when requiring files from disk in userland
-      const pathToPackageJson = require.resolve(`${packageName}/package.json`, { paths: [ args.resolveDir ] })
+
+      let pathToPackageJson
+      try {
+        pathToPackageJson = require.resolve(`${packageName}/package.json`, { paths: [ args.resolveDir ] })
+      } catch (err) {
+        if (err.code === 'MODULE_NOT_FOUND') {
+          console.warn(`Unable to open "${packageName}/package.json". Is the "${packageName}" package dead code?`)
+          return
+        } else {
+          throw err
+        }
+      }
+
       const pkg = require(pathToPackageJson)
 
       if (DEBUG) {