ref(nextjs): Exclude cross-platform tracing code from bundles

packages/nextjs/src/config/types.ts

@@ -42,6 +42,9 @@ export type WebpackConfigObject = {
   output: { filename: string; path: string };
   target: string;
   context: string;
+  resolve?: {
+    alias?: { [key: string]: string | boolean };
+  };
 } & {
   // other webpack options
   [key: string]: unknown;

packages/nextjs/src/config/webpack.ts

@@ -60,6 +60,24 @@ export function constructWebpackConfigFunction(
     const origEntryProperty = newConfig.entry;
     newConfig.entry = async () => addSentryToEntryProperty(origEntryProperty, buildContext);
 
+    // In webpack 5, you can get webpack to replace any module you'd like with an empty object, just by setting its
+    // `resolve.alias` value to `false`. Not much of our code is neatly separated into "things node needs" and "things
+    // the browser needs," but where it is, we can save ~1.6 kb in eventual bundle size by excluding code we know we
+    // don't need. (Normally this would only matter for the client side, but because vercel turns backend code into
+    // serverless functions, it's worthwhile to do it for both.)
+    if (buildContext.webpack.version.startsWith('5')) {
+      const excludedTracingDir = buildContext.isServer ? 'browser' : 'integrations/node';
+      newConfig.resolve = {
+        ...newConfig.resolve,
+        alias: {
+          ...newConfig.resolve?.alias,
+          [path.resolve(buildContext.dir, `./node_modules/@sentry/tracing/esm/${excludedTracingDir}`)]: false,
+          // TODO It's not clear if it will ever pull from `dist` (in testing it never does), so we may not need this.
+          [path.resolve(buildContext.dir, `./node_modules/@sentry/tracing/dist/${excludedTracingDir}`)]: false,
+        },
+      };
+    }
+
     // Enable the Sentry plugin (which uploads source maps to Sentry when not in dev) by default
     const enableWebpackPlugin = buildContext.isServer
       ? !userNextConfig.sentry?.disableServerWebpackPlugin

packages/tracing/src/integrations/index.ts

@@ -1,4 +1,4 @@
-export { Express } from './express';
-export { Postgres } from './postgres';
-export { Mysql } from './mysql';
-export { Mongo } from './mongo';
+export { Express } from './node/express';
+export { Postgres } from './node/postgres';
+export { Mysql } from './node/mysql';
+export { Mongo } from './node/mongo';

packages/tracing/test/integrations/mongo.test.ts → packages/tracing/test/integrations/node/mongo.test.ts

@@ -1,8 +1,8 @@
 /* eslint-disable @typescript-eslint/unbound-method */
 import { Hub, Scope } from '@sentry/hub';
 
-import { Mongo } from '../../src/integrations/mongo';
-import { Span } from '../../src/span';
+import { Mongo } from '../../../src/integrations/node/mongo';
+import { Span } from '../../../src/span';
 
 class Collection {
   public collectionName: string = 'mockedCollectionName';

packages/tracing/test/integrations/postgres.test.ts → packages/tracing/test/integrations/node/postgres.test.ts

@@ -1,8 +1,8 @@
 /* eslint-disable @typescript-eslint/unbound-method */
 import { Hub, Scope } from '@sentry/hub';
 
-import { Postgres } from '../../src/integrations/postgres';
-import { Span } from '../../src/span';
+import { Postgres } from '../../../src/integrations/node/postgres';
+import { Span } from '../../../src/span';
 
 class PgClient {
   // https://node-postgres.com/api/client#clientquery