performance: enable minification for the server bundles (#51831)

This PR makes the server code be minified.

## Why

This will improve performance of the server code because of the lesser
size, lesser time to parse and lesser code via tree sharking.

Cons: this should lead to increased build times, so a
`disableServerMinification` config was added


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link NEXT-1319

packages/next/src/build/webpack-config.ts

@@ -1766,7 +1766,11 @@ export default async function getBaseWebpackConfig(
       runtimeChunk: isClient
         ? { name: CLIENT_STATIC_FILES_RUNTIME_WEBPACK }
         : undefined,
-      minimize: !dev && (isClient || isEdgeServer),
+      minimize:
+        !dev &&
+        (isClient ||
+          isEdgeServer ||
+          (isNodeServer && config.experimental.serverMinification)),
       minimizer: [
         // Minify JavaScript
         (compiler: webpack.Compiler) => {
@@ -2724,6 +2728,7 @@ export default async function getBaseWebpackConfig(
     experimental: config.experimental,
     disableStaticImages: config.images.disableStaticImages,
     transpilePackages: config.transpilePackages,
+    serverSourceMaps: config.experimental.serverSourceMaps,
   })
 
   // @ts-ignore Cache exists

packages/next/src/build/webpack/config/blocks/base.ts

@@ -34,6 +34,7 @@ export const base = curry(function base(
   } else {
     if (
       ctx.isEdgeRuntime ||
+      (ctx.isServer && ctx.serverSourceMaps) ||
       // Enable browser sourcemaps:
       (ctx.productionBrowserSourceMaps && ctx.isClient)
     ) {

packages/next/src/build/webpack/config/index.ts

@@ -25,6 +25,7 @@ export async function buildConfiguration(
     transpilePackages,
     experimental,
     disableStaticImages,
+    serverSourceMaps,
   }: {
     hasAppDir: boolean
     supportedBrowsers: string[] | undefined
@@ -41,6 +42,7 @@ export async function buildConfiguration(
     future: NextConfigComplete['future']
     experimental: NextConfigComplete['experimental']
     disableStaticImages: NextConfigComplete['disableStaticImages']
+    serverSourceMaps: NextConfigComplete['experimental']['serverSourceMaps']
   }
 ): Promise<webpack.Configuration> {
   const ctx: ConfigurationContext = {
@@ -64,6 +66,7 @@ export async function buildConfiguration(
     transpilePackages,
     future,
     experimental,
+    serverSourceMaps: serverSourceMaps ?? false,
   }
 
   let fns = [base(ctx), css(ctx)]

packages/next/src/build/webpack/config/utils.ts

@@ -22,6 +22,7 @@ export type ConfigurationContext = {
 
   sassOptions: any
   productionBrowserSourceMaps: boolean
+  serverSourceMaps: boolean
 
   transpilePackages: NextConfigComplete['transpilePackages']
 

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

@@ -512,6 +512,12 @@ const configSchema = {
         logging: {
           type: 'string',
         },
+        serverMinification: {
+          type: 'boolean',
+        },
+        serverSourceMaps: {
+          type: 'boolean',
+        },
       },
       type: 'object',
     },

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

@@ -287,6 +287,16 @@ export interface ExperimentalConfig {
    * Allows adjusting body parser size limit for server actions.
    */
   serverActionsBodySizeLimit?: SizeLimit
+
+  /**
+   * enables the minification of server code.
+   */
+  serverMinification?: boolean
+
+  /**
+   * Enables source maps generation for the server production bundle.
+   */
+  serverSourceMaps?: boolean
 }
 
 export type ExportPathMap = {
@@ -670,6 +680,8 @@ export const defaultConfig: NextConfig = {
   output: !!process.env.NEXT_PRIVATE_STANDALONE ? 'standalone' : undefined,
   modularizeImports: undefined,
   experimental: {
+    serverMinification: false,
+    serverSourceMaps: false,
     caseSensitiveRoutes: false,
     useDeploymentId: false,
     deploymentId: undefined,