Fix encoding for env files in serverless mode (#14750)

This makes sure to base64 encode the `.env*` file contents before passing them in the URL for the serverless-loader since `!` is a special character in this case which can cause webpack to fail to build

Closes: https://github.com/vercel/next.js/issues/14749

packages/next/build/entries.ts

@@ -92,7 +92,10 @@ export function createEntrypoints(
         })
       : '',
     previewProps: JSON.stringify(previewMode),
-    loadedEnvFiles: JSON.stringify(loadedEnvFiles),
+    // base64 encode to make sure contents don't break webpack URL loading
+    loadedEnvFiles: Buffer.from(JSON.stringify(loadedEnvFiles)).toString(
+      'base64'
+    ),
   }
 
   Object.keys(pages).forEach((page) => {

packages/next/build/webpack/loaders/next-serverless-loader.ts

@@ -90,7 +90,7 @@ const nextServerlessLoader: loader.Loader = function () {
     : ''
   const envLoading = `
     const { processEnv } = require('next/dist/lib/load-env-config')
-    processEnv(${loadedEnvFiles})
+    processEnv(${Buffer.from(loadedEnvFiles, 'base64').toString()})
   `
 
   const runtimeConfigImports = runtimeConfig

test/integration/env-config/app/.env

-PROCESS_ENV_KEY=env
+PROCESS_ENV_KEY="env"
 ENV_FILE_KEY=env
 ENV_FILE_LOCAL_OVERRIDE_TEST=env
 ENV_FILE_DEVELOPMENT_OVERRIDE_TEST=env
@@ -10,4 +10,5 @@ ENV_FILE_TEST_LOCAL_OVERRIDEOVERRIDE_TEST=env
 NEXT_PUBLIC_TEST_DEST=another
 ENV_FILE_EXPANDED=$ENV_FILE_KEY
 ENV_FILE_EXPANDED_CONCAT=hello-${ENV_FILE_KEY}
-ENV_FILE_EXPANDED_ESCAPED=\$ENV_FILE_KEY
\ No newline at end of file
+ENV_FILE_EXPANDED_ESCAPED=\$ENV_FILE_KEY
+ENV_FILE_KEY_EXCLAMATION="hello!"
\ No newline at end of file

test/integration/env-config/app/pages/api/all.js

@@ -18,6 +18,7 @@ const variables = [
   'ENV_FILE_EXPANDED',
   'ENV_FILE_EXPANDED_CONCAT',
   'ENV_FILE_EXPANDED_ESCAPED',
+  'ENV_FILE_KEY_EXCLAMATION',
 ]
 
 const items = {}

test/integration/env-config/app/pages/index.js

@@ -18,6 +18,7 @@ const variables = [
   'ENV_FILE_EXPANDED',
   'ENV_FILE_EXPANDED_CONCAT',
   'ENV_FILE_EXPANDED_ESCAPED',
+  'ENV_FILE_KEY_EXCLAMATION',
 ]
 
 export async function getStaticProps() {

test/integration/env-config/app/pages/some-ssg.js

@@ -18,6 +18,7 @@ const variables = [
   'ENV_FILE_EXPANDED',
   'ENV_FILE_EXPANDED_CONCAT',
   'ENV_FILE_EXPANDED_ESCAPED',
+  'ENV_FILE_KEY_EXCLAMATION',
 ]
 
 export async function getStaticProps() {

test/integration/env-config/app/pages/some-ssp.js

@@ -18,6 +18,7 @@ const variables = [
   'ENV_FILE_EXPANDED',
   'ENV_FILE_EXPANDED_CONCAT',
   'ENV_FILE_EXPANDED_ESCAPED',
+  'ENV_FILE_KEY_EXCLAMATION',
 ]
 
 export async function getServerSideProps() {

test/integration/env-config/test/index.test.js

@@ -50,6 +50,7 @@ const runTests = (mode = 'dev') => {
     expect(data.ENV_FILE_EXPANDED).toBe('env')
     expect(data.ENV_FILE_EXPANDED_CONCAT).toBe('hello-env')
     expect(data.ENV_FILE_EXPANDED_ESCAPED).toBe('$ENV_FILE_KEY')
+    expect(data.ENV_FILE_KEY_EXCLAMATION).toBe('hello!')
   }
 
   it('should have process environment override .env', async () => {