Expose dotenv loading under separate package

.eslintignore

@@ -13,3 +13,4 @@ packages/next-codemod/transforms/__testfixtures__/**/*
 packages/next-codemod/transforms/__tests__/**/*
 packages/next-codemod/**/*.js
 packages/next-codemod/**/*.d.ts
+packages/next-env/**/*.d.ts

.prettierignore

@@ -13,3 +13,4 @@ packages/next-codemod/transforms/__testfixtures__/**/*
 packages/next-codemod/transforms/__tests__/**/*
 packages/next-codemod/**/*.js
 packages/next-codemod/**/*.d.ts
+packages/next-env/**/*.d.ts

packages/next-env/.gitignore

@@ -0,0 +1 @@
+types

packages/next-env/README.md

@@ -0,0 +1,3 @@
+# `@next/env`
+
+Next.js' util for loading dotenv files in with the proper priorities

packages/next/lib/load-env-config.ts → packages/next-env/index.ts

@@ -1,8 +1,8 @@
-import fs from 'fs'
-import path from 'path'
-import * as log from '../build/output/log'
-import dotenvExpand from 'next/dist/compiled/dotenv-expand'
-import dotenv, { DotenvConfigOutput } from 'next/dist/compiled/dotenv'
+/* eslint-disable import/no-extraneous-dependencies */
+import * as fs from 'fs'
+import * as path from 'path'
+import * as dotenv from 'dotenv'
+import dotenvExpand from 'dotenv-expand'
 
 export type Env = { [key: string]: string }
 export type LoadedEnvFiles = Array<{
@@ -13,14 +13,19 @@ export type LoadedEnvFiles = Array<{
 let combinedEnv: Env | undefined = undefined
 let cachedLoadedEnvFiles: LoadedEnvFiles = []
 
-export function processEnv(loadedEnvFiles: LoadedEnvFiles, dir?: string) {
+type Log = {
+  info: (...args: any[]) => void
+  error: (...args: any[]) => void
+}
+
+export function processEnv(
+  loadedEnvFiles: LoadedEnvFiles,
+  dir?: string,
+  log: Log = console
+) {
   // don't reload env if we already have since this breaks escaped
   // environment values e.g. \$ENV_FILE_KEY
-  if (
-    combinedEnv ||
-    process.env.__NEXT_PROCESSED_ENV ||
-    !loadedEnvFiles.length
-  ) {
+  if (process.env.__NEXT_PROCESSED_ENV || loadedEnvFiles.length === 0) {
     return process.env as Env
   }
   // flag that we processed the environment values in case a serverless
@@ -32,7 +37,7 @@ export function processEnv(loadedEnvFiles: LoadedEnvFiles, dir?: string) {
 
   for (const envFile of loadedEnvFiles) {
     try {
-      let result: DotenvConfigOutput = {}
+      let result: dotenv.DotenvConfigOutput = {}
       result.parsed = dotenv.parse(envFile.contents)
 
       result = dotenvExpand(result)
@@ -62,7 +67,8 @@ export function processEnv(loadedEnvFiles: LoadedEnvFiles, dir?: string) {
 
 export function loadEnvConfig(
   dir: string,
-  dev?: boolean
+  dev?: boolean,
+  log: Log = console
 ): {
   combinedEnv: Env
   loadedEnvFiles: LoadedEnvFiles

packages/next-env/package.json

@@ -0,0 +1,37 @@
+{
+  "name": "@next/env",
+  "version": "9.5.4-canary.21",
+  "keywords": [
+    "react",
+    "next",
+    "next.js",
+    "dotenv"
+  ],
+  "description": "Next.js dotenv file loading",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/vercel/next.js",
+    "directory": "packages/next-env"
+  },
+  "author": "Next.js Team <support@vercel.com>",
+  "license": "MIT",
+  "main": "dist/index.js",
+  "types": "types/index.d.ts",
+  "files": [
+    "dist",
+    "types"
+  ],
+  "scripts": {
+    "build": "ncc build ./index.ts -w -o dist/",
+    "prerelease": "rimraf ./dist/",
+    "types": "tsc index.ts --declaration --emitDeclarationOnly --declarationDir types --esModuleInterop",
+    "release": "ncc build ./index.ts -o ./dist/ --minify --no-cache --no-source-map-register",
+    "prepublish": "yarn release && yarn types"
+  },
+  "devDependencies": {
+    "@types/dotenv": "8.2.0",
+    "@zeit/ncc": "^0.20.4",
+    "dotenv": "8.2.0",
+    "dotenv-expand": "5.1.0"
+  }
+}

packages/next-env/tsconfig.json

@@ -0,0 +1,10 @@
+{
+  "compilerOptions": {
+    "target": "es2015",
+    "moduleResolution": "node",
+    "strict": true,
+    "resolveJsonModule": true,
+    "esModuleInterop": true,
+    "skipLibCheck": false
+  }
+}

packages/next/build/entries.ts

@@ -8,7 +8,7 @@ import { normalizePagePath } from '../next-server/server/normalize-page-path'
 import { warn } from './output/log'
 import { ClientPagesLoaderOptions } from './webpack/loaders/next-client-pages-loader'
 import { ServerlessLoaderQuery } from './webpack/loaders/next-serverless-loader'
-import { LoadedEnvFiles } from '../lib/load-env-config'
+import { LoadedEnvFiles } from '@next/env'
 
 type PagesMapping = {
   [page: string]: string

packages/next/build/index.ts

@@ -21,7 +21,7 @@ import loadCustomRoutes, {
   Redirect,
   RouteType,
 } from '../lib/load-custom-routes'
-import { loadEnvConfig } from '../lib/load-env-config'
+import { loadEnvConfig } from '@next/env'
 import { recursiveDelete } from '../lib/recursive-delete'
 import { verifyTypeScriptSetup } from '../lib/verifyTypeScriptSetup'
 import {
@@ -112,7 +112,7 @@ export default async function build(
   }
 
   // attempt to load global env values so they are available in next.config.js
-  const { loadedEnvFiles } = loadEnvConfig(dir)
+  const { loadedEnvFiles } = loadEnvConfig(dir, false, Log)
 
   const config = loadConfig(PHASE_PRODUCTION_BUILD, dir, conf)
   const { target } = config

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

@@ -117,7 +117,7 @@ const nextServerlessLoader: loader.Loader = function () {
     `
     : ''
   const envLoading = `
-    const { processEnv } = require('next/dist/lib/load-env-config')
+    const { processEnv } = require('@next/env')
     processEnv(${Buffer.from(loadedEnvFiles, 'base64').toString()})
   `