Update to only apply experimental process.env stub in development

packages/next/build/webpack-config.ts

@@ -867,15 +867,10 @@ export default async function getBaseWebpackConfig(
             }
           : undefined),
         // stub process.env with proxy to warn a missing value is
-        // being accessed
-        ...(config.experimental.pageEnv
+        // being accessed in development mode
+        ...(config.experimental.pageEnv && process.env.NODE_ENV !== 'production'
           ? {
-              'process.env':
-                process.env.NODE_ENV === 'production'
-                  ? isServer
-                    ? 'process.env'
-                    : '{}'
-                  : `
+              'process.env': `
             new Proxy(${isServer ? 'process.env' : '{}'}, {
               get(target, prop) {
                 if (typeof target[prop] === 'undefined') {

test/integration/process-env-stub/components/hello.js

@@ -0,0 +1,11 @@
+import { PHASE_PRODUCTION_BUILD } from 'next/constants'
+
+const { NODE_ENV } = process.env
+const { NEXT_PHASE } = process.env
+const SENTRY_DSN = process.env.NEXT_PUBLIC_SENTRY_DSN
+
+if (NODE_ENV !== 'development' && NEXT_PHASE !== PHASE_PRODUCTION_BUILD) {
+  console.log('next start', SENTRY_DSN)
+}
+
+export default () => process.env.HELLO || 'hi'

test/integration/process-env-stub/pages/missing.js

@@ -1,4 +1,15 @@
+import dynamic from 'next/dynamic'
+
+const Hello = dynamic(() => import('../components/hello'), { ssr: true })
+
 export default () => {
-  console.log(process.env.hi)
-  return <p>hi there 👋</p>
+  // make sure we handle this syntax correctly
+  const { hi } = process.env
+  console.log(hi)
+  return (
+    <>
+      <p>hi there 👋</p>
+      <Hello />
+    </>
+  )
 }

test/integration/process-env-stub/test/index.test.js

@@ -6,6 +6,8 @@ import {
   launchApp,
   renderViaHTTP,
   waitFor,
+  nextBuild,
+  nextStart,
 } from 'next-test-utils'
 import { join } from 'path'
 import webdriver from 'next-webdriver'
@@ -54,57 +56,113 @@ const checkMissingClient = async (pathname, prop, shouldWarn = false) => {
 }
 
 describe('process.env stubbing', () => {
-  beforeAll(async () => {
-    appPort = await findPort()
-    app = await launchApp(appDir, appPort, {
-      env: {
-        NEXT_PUBLIC_HI: 'hi',
-        I_SHOULD_BE_HERE: 'hello',
-      },
-      onStderr(msg) {
-        stderr += msg || ''
-      },
+  describe('dev mode', () => {
+    beforeAll(async () => {
+      appPort = await findPort()
+      app = await launchApp(appDir, appPort, {
+        env: {
+          NEXT_PUBLIC_HI: 'hi',
+          I_SHOULD_BE_HERE: 'hello',
+        },
+        onStderr(msg) {
+          stderr += msg || ''
+        },
+      })
     })
-  })
-  afterAll(() => killApp(app))
+    afterAll(() => killApp(app))
 
-  describe('server side', () => {
-    it('should not show missing env value when its not missing public', async () => {
-      await checkMissing('/not-missing', 'NEXT_PUBLIC_HI')
-    })
+    describe('server side', () => {
+      it('should not show missing env value when its not missing public', async () => {
+        await checkMissing('/not-missing', 'NEXT_PUBLIC_HI')
+      })
 
-    it('should not show missing env value when its not missing runtime', async () => {
-      await checkMissing('/also-not-missing', 'I_SHOULD_BE_HERE')
-    })
+      it('should not show missing env value when its not missing runtime', async () => {
+        await checkMissing('/also-not-missing', 'I_SHOULD_BE_HERE')
+      })
 
-    it('should show missing env value when its missing normal', async () => {
-      await checkMissing('/missing', 'hi', true)
-    })
+      it('should show missing env value when its missing normal', async () => {
+        await checkMissing('/missing', 'hi', true)
+      })
 
-    it('should show missing env value when its missing GSP', async () => {
-      await checkMissing('/missing-gsp', 'SECRET', true)
-    })
+      it('should show missing env value when its missing GSP', async () => {
+        await checkMissing('/missing-gsp', 'SECRET', true)
+      })
+
+      it('should show missing env value when its missing GSSP', async () => {
+        await checkMissing('/missing-gssp', 'SECRET', true)
+      })
 
-    it('should show missing env value when its missing GSSP', async () => {
-      await checkMissing('/missing-gssp', 'SECRET', true)
+      it('should show missing env value when its missing API', async () => {
+        await checkMissing('/api/hi', 'where_is_it', true)
+      })
     })
 
-    it('should show missing env value when its missing API', async () => {
-      await checkMissing('/api/hi', 'where_is_it', true)
+    describe('client side', () => {
+      it('should not show missing env value when its not missing public', async () => {
+        await checkMissingClient('/not-missing', 'NEXT_PUBLIC_HI')
+      })
+
+      it('should show missing env value when its missing runtime', async () => {
+        await checkMissingClient('/also-not-missing', 'I_SHOULD_BE_HERE', true)
+      })
+
+      it('should show missing env value when its missing normal', async () => {
+        await checkMissingClient('/missing', 'hi', true)
+      })
     })
   })
 
-  describe('client side', () => {
-    it('should not show missing env value when its not missing public', async () => {
-      await checkMissingClient('/not-missing', 'NEXT_PUBLIC_HI')
+  describe('production mode', () => {
+    beforeAll(async () => {
+      const { code } = await nextBuild(appDir)
+      if (code !== 0) throw new Error(`build failed with code ${code}`)
+      appPort = await findPort()
+      app = await nextStart(appDir, appPort, {
+        onStderr(msg) {
+          stderr += msg || ''
+        },
+      })
     })
+    afterAll(() => killApp(app))
 
-    it('should show missing env value when its missing runtime', async () => {
-      await checkMissingClient('/also-not-missing', 'I_SHOULD_BE_HERE', true)
+    describe('server side', () => {
+      it('should not show missing env value when its not missing public', async () => {
+        await checkMissing('/not-missing', 'NEXT_PUBLIC_HI')
+      })
+
+      it('should not show missing env value when its not missing runtime', async () => {
+        await checkMissing('/also-not-missing', 'I_SHOULD_BE_HERE')
+      })
+
+      it('should not show missing env value when its missing normal', async () => {
+        await checkMissing('/missing', 'hi')
+      })
+
+      it('should not show missing env value when its missing GSP', async () => {
+        await checkMissing('/missing-gsp', 'SECRET')
+      })
+
+      it('should not show missing env value when its missing GSSP', async () => {
+        await checkMissing('/missing-gssp', 'SECRET')
+      })
+
+      it('should not show missing env value when its missing API', async () => {
+        await checkMissing('/api/hi', 'where_is_it')
+      })
     })
 
-    it('should show missing env value when its missing normal', async () => {
-      await checkMissingClient('/missing', 'hi', true)
+    describe('client side', () => {
+      it('should not show missing env value when its not missing public', async () => {
+        await checkMissingClient('/not-missing', 'NEXT_PUBLIC_HI')
+      })
+
+      it('should not show missing env value when its missing runtime', async () => {
+        await checkMissingClient('/also-not-missing', 'I_SHOULD_BE_HERE')
+      })
+
+      it('should not show missing env value when its missing normal', async () => {
+        await checkMissingClient('/missing', 'hi')
+      })
     })
   })
 })