Check next.config.js settings

packages/next/build/index.ts

@@ -47,8 +47,8 @@ import loadConfig, {
 import {
   eventBuildCompleted,
   eventBuildOptimize,
+  eventCliSession,
   eventNextPlugins,
-  eventVersion,
 } from '../telemetry/events'
 import { Telemetry } from '../telemetry/storage'
 import { CompilerResult, runCompiler } from './compiler'
@@ -157,7 +157,7 @@ export default async function build(dir: string, conf = null): Promise<void> {
   let hasPublicDir = false
 
   telemetry.record(
-    eventVersion({
+    eventCliSession(PHASE_PRODUCTION_BUILD, dir, {
       cliCommand: 'build',
       isSrcDir: path.relative(dir, pagesDir!).startsWith('src'),
       hasNowJson: !!(await findUp('now.json', { cwd: dir })),

packages/next/export/index.ts

@@ -31,7 +31,7 @@ import {
 import loadConfig, {
   isTargetLikeServerless,
 } from '../next-server/server/config'
-import { eventVersion } from '../telemetry/events'
+import { eventCliSession } from '../telemetry/events'
 import { Telemetry } from '../telemetry/storage'
 
 const mkdirp = promisify(mkdirpModule)
@@ -104,7 +104,7 @@ export default async function(
 
   if (telemetry) {
     telemetry.record(
-      eventVersion({
+      eventCliSession(PHASE_EXPORT, distDir, {
         cliCommand: 'export',
         isSrcDir: null,
         hasNowJson: !!(await findUp('now.json', { cwd: dir })),

packages/next/next-server/server/config.ts

@@ -198,7 +198,7 @@ function assignDefaults(userConfig: { [key: string]: any }) {
   return result
 }
 
-function normalizeConfig(phase: string, config: any) {
+export function normalizeConfig(phase: string, config: any) {
   if (typeof config === 'function') {
     config = config(phase, { defaultConfig })
 

packages/next/server/next-dev-server.ts

@@ -1,14 +1,15 @@
 import AmpHtmlValidator from 'amphtml-validator'
+import findUp from 'find-up'
 import fs from 'fs'
 import { IncomingMessage, ServerResponse } from 'http'
 import { join, relative } from 'path'
 import React from 'react'
 import { UrlWithParsedQuery } from 'url'
 import { promisify } from 'util'
 import Watchpack from 'watchpack'
-import findUp from 'find-up'
 import { ampValidation } from '../build/output/index'
 import * as Log from '../build/output/log'
+import checkCustomRoutes from '../lib/check-custom-routes'
 import { PUBLIC_DIR_MIDDLEWARE_CONFLICT } from '../lib/constants'
 import { findPagesDir } from '../lib/find-pages-dir'
 import { verifyTypeScriptSetup } from '../lib/verifyTypeScriptSetup'
@@ -21,13 +22,12 @@ import {
 } from '../next-server/lib/router/utils'
 import Server, { ServerConstructor } from '../next-server/server/next-server'
 import { normalizePagePath } from '../next-server/server/normalize-page-path'
-import Router, { route, Params } from '../next-server/server/router'
-import { eventVersion } from '../telemetry/events'
+import Router, { Params, route } from '../next-server/server/router'
+import { eventCliSession } from '../telemetry/events'
 import { Telemetry } from '../telemetry/storage'
 import ErrorDebug from './error-debug'
 import HotReloader from './hot-reloader'
 import { findPageFile } from './lib/find-page-file'
-import checkCustomRoutes from '../lib/check-custom-routes'
 
 if (typeof React.Suspense === 'undefined') {
   throw new Error(
@@ -230,7 +230,7 @@ export default class DevServer extends Server {
 
     const telemetry = new Telemetry({ distDir: this.distDir })
     telemetry.record(
-      eventVersion({
+      eventCliSession(PHASE_DEVELOPMENT_SERVER, this.distDir, {
         cliCommand: 'dev',
         isSrcDir: relative(this.dir, this.pagesDir!).startsWith('src'),
         hasNowJson: !!(await findUp('now.json', { cwd: this.dir })),

packages/next/telemetry/events/version.ts

@@ -1,3 +1,13 @@
+import Babel from '@babel/core'
+import findUp from 'find-up'
+import {
+  CONFIG_FILE,
+  PHASE_DEVELOPMENT_SERVER,
+  PHASE_EXPORT,
+  PHASE_PRODUCTION_BUILD,
+} from '../../next-server/lib/constants'
+import { normalizeConfig } from '../../next-server/server/config'
+
 const EVENT_VERSION = 'NEXT_CLI_SESSION_STARTED'
 
 type EventCliSessionStarted = {
@@ -7,27 +17,83 @@ type EventCliSessionStarted = {
   isSrcDir: boolean | null
   hasNowJson: boolean
   isCustomServer: boolean | null
+  hasNextConfig: boolean
+  buildTarget: string
+  hasWebpackConfig: boolean
+  hasBabelConfig: boolean
+}
+
+function hasBabelConfig(dir: string): boolean {
+  try {
+    const res = Babel.loadPartialConfig({ cwd: dir }) as any
+    return res.hasFilesystemConfig()
+  } catch {
+    return false
+  }
+}
+
+type NextConfigurationPhase =
+  | typeof PHASE_DEVELOPMENT_SERVER
+  | typeof PHASE_PRODUCTION_BUILD
+  | typeof PHASE_EXPORT
+
+function getNextConfig(
+  phase: NextConfigurationPhase,
+  dir: string
+): { [key: string]: any } | null {
+  try {
+    const configurationPath = findUp.sync(CONFIG_FILE, {
+      cwd: dir,
+    })
+
+    if (configurationPath) {
+      // This should've already been loaded, and thus should be cached / won't
+      // be re-evaluated.
+      const configurationModule = require(configurationPath)
+
+      // Re-normalize the configuration.
+      return normalizeConfig(
+        phase,
+        configurationModule.default || configurationModule
+      )
+    }
+  } catch {
+    // ignored
+  }
+  return null
 }
 
-export function eventVersion(
-  event: Omit<EventCliSessionStarted, 'nextVersion' | 'nodeVersion'>
+export function eventCliSession(
+  phase: NextConfigurationPhase,
+  dir: string,
+  event: Omit<
+    EventCliSessionStarted,
+    | 'nextVersion'
+    | 'nodeVersion'
+    | 'hasNextConfig'
+    | 'buildTarget'
+    | 'hasWebpackConfig'
+    | 'hasBabelConfig'
+  >
 ): { eventName: string; payload: EventCliSessionStarted }[] {
   // This should be an invariant, if it fails our build tooling is broken.
   if (typeof process.env.__NEXT_VERSION !== 'string') {
     return []
   }
 
-  return [
-    {
-      eventName: EVENT_VERSION,
-      payload: {
-        nextVersion: process.env.__NEXT_VERSION,
-        nodeVersion: process.version,
-        cliCommand: event.cliCommand,
-        isSrcDir: event.isSrcDir,
-        hasNowJson: event.hasNowJson,
-        isCustomServer: event.isCustomServer,
-      } as EventCliSessionStarted,
-    },
-  ]
+  const userConfiguration = getNextConfig(phase, dir)
+
+  const payload: EventCliSessionStarted = {
+    nextVersion: process.env.__NEXT_VERSION,
+    nodeVersion: process.version,
+    cliCommand: event.cliCommand,
+    isSrcDir: event.isSrcDir,
+    hasNowJson: event.hasNowJson,
+    isCustomServer: event.isCustomServer,
+    hasNextConfig: !!userConfiguration,
+    buildTarget: userConfiguration?.target ?? 'default',
+    hasWebpackConfig: typeof userConfiguration?.webpack === 'function',
+    hasBabelConfig: hasBabelConfig(dir),
+  }
+  return [{ eventName: EVENT_VERSION, payload }]
 }