feat(env): support dotenv-expand to contains process env (#10370)

Author: Dunqing

packages/vite/src/node/env.ts

@@ -40,11 +40,18 @@ export function loadEnv(
   )
 
   // let environment variables use each other
-  dotenvExpand({
-    parsed,
+  const expandParsed = dotenvExpand({
+    parsed: {
+      ...(process.env as any),
+      ...parsed
+    },
     // prevent process.env mutation
     ignoreProcessEnv: true
-  } as any)
+  } as any).parsed!
+
+  Object.keys(parsed).forEach((key) => {
+    parsed[key] = expandParsed[key]
+  })
 
   // only keys that start with prefix are exposed to client
   for (const [key, value] of Object.entries(parsed)) {

playground/env/.env

@@ -1,4 +1,5 @@
 VITE_CUSTOM_ENV_VARIABLE=1
 CUSTOM_PREFIX_ENV_VARIABLE=1
 VITE_EFFECTIVE_MODE_FILE_NAME=.env
-VITE_BOOL=true
+VITE_BOOL=true
+VITE_EXPAND=$EXPAND

playground/env/__tests__/env.spec.ts

@@ -45,6 +45,10 @@ test('NODE_ENV', async () => {
   expect(await page.textContent('.node-env')).toBe(process.env.NODE_ENV)
 })
 
+test('expand', async () => {
+  expect(await page.textContent('.expand')).toBe('expand')
+})
+
 test('env object', async () => {
   const envText = await page.textContent('.env-object')
   expect(JSON.parse(envText)).toMatchObject({

playground/env/index.html

@@ -14,6 +14,7 @@ <h1>Environment Variables</h1>
 <p>import.meta.env.VITE_INLINE: <code class="inline"></code></p>
 <p>typeof import.meta.env.VITE_BOOL: <code class="bool"></code></p>
 <p>process.env.NODE_ENV: <code class="node-env"></code></p>
+<p>import.meta.env.VITE_EXPAND: <code class="expand"></code></p>
 <p>import.meta.env: <span class="pre env-object"></span></p>
 <p>import.meta.url: <span class="pre url"></span></p>
 
@@ -29,6 +30,7 @@ <h1>Environment Variables</h1>
   text('.bool', typeof import.meta.env.VITE_BOOL)
   text('.node-env', process.env.NODE_ENV)
   text('.env-object', JSON.stringify(import.meta.env, null, 2))
+  text('.expand', import.meta.env.VITE_EXPAND)
 
   function text(el, text) {
     document.querySelector(el).textContent = text

playground/env/vite.config.js

@@ -1,5 +1,7 @@
 const { defineConfig } = require('vite')
 
+process.env.EXPAND = 'expand'
+
 module.exports = defineConfig({
   base: '/env/',
   envPrefix: ['VITE_', 'CUSTOM_PREFIX_'],