如何在NX Monorepo中配置多环境.env文件（Nest.js项目）

1. 规范项目结构 #

给每个Nest.js应用创建独立的environment文件夹，存放各环境配置文件：

apps/be-license-server/
├── environment/
│   ├── local.env
│   ├── dev.env
│   └── prod.env
├── src/
├── project.json
└── webpack.config.js

2. 修改project.json配置 #

在build和serve的环境配置中指定对应env文件，同时将environment目录加入静态资源打包列表，确保运行时能读取到文件：

{
  "name": "be-license-server",
  "$schema": "../../node_modules/nx/schemas/project-schema.json",
  "sourceRoot": "apps/be-license-server/src",
  "projectType": "application",
  "targets": {
    "build": {
      "executor": "@nx/webpack:webpack",
      "outputs": ["{options.outputPath}"],
      "defaultConfiguration": "production",
      "options": {
        "target": "node",
        "compiler": "tsc",
        "outputPath": "dist/apps/be-license-server",
        "main": "apps/be-license-server/src/main.ts",
        "tsConfig": "apps/be-license-server/tsconfig.app.json",
        "assets": [
          "apps/be-license-server/src/assets",
          {
            "input": "apps/be-license-server/environment",
            "output": "./environment",
            "glob": "*.env"
          }
        ],
        "isolatedConfig": true,
        "webpackConfig": "apps/be-license-server/webpack.config.js"
      },
      "configurations": {
        "development": {
          "define": {
            "process.env.NODE_ENV": "\"development\""
          },
          "envFile": "apps/be-license-server/environment/dev.env"
        },
        "production": {
          "define": {
            "process.env.NODE_ENV": "\"production\""
          },
          "envFile": "apps/be-license-server/environment/prod.env"
        },
        "local": {
          "define": {
            "process.env.NODE_ENV": "\"local\""
          },
          "envFile": "apps/be-license-server/environment/local.env"
        }
      }
    },
    "serve": {
      "executor": "@nx/js:node",
      "defaultConfiguration": "local",
      "options": {
        "buildTarget": "be-license-server:build"
      },
      "configurations": {
        "local": {
          "buildTarget": "be-license-server:build:local",
          "envFile": "apps/be-license-server/environment/local.env"
        },
        "development": {
          "buildTarget": "be-license-server:build:development",
          "envFile": "apps/be-license-server/environment/dev.env"
        },
        "production": {
          "buildTarget": "be-license-server:build:production",
          "envFile": "apps/be-license-server/environment/prod.env"
        }
      }
    },
    "lint": {
      "executor": "@nx/linter:eslint",
      "outputs": ["{options.outputFile}"],
      "options": {
        "lintFilePatterns": ["apps/be-license-server/**/*.ts"]
      }
    }
  },
  "tags": ["prisma"]
}

3. Webpack编译时注入环境变量（可选） #

如果需要在编译阶段将env变量注入代码，使用dotenv-webpack插件：

1. 安装依赖

npm install dotenv-webpack --save-dev

2. 修改webpack.config.js

const { composePlugins, withNx } = require('@nx/webpack');
const Dotenv = require('dotenv-webpack');
const path = require('path');

module.exports = composePlugins(withNx(), (config, { options, context }) => {
  const envPath = path.resolve(__dirname, `environment/${context.configuration || 'local'}.env`);
  config.plugins.push(new Dotenv({ path: envPath }));
  return config;
});

4. Nest.js应用中读取环境变量 #

有两种读取方式：

• 编译时注入的变量直接用process.env.XXX调用
• 运行时动态加载（适合切换环境），用dotenv包：
  1. 安装依赖

  npm install dotenv
  

  2. 在main.ts中加载

  import { NestFactory } from '@nestjs/core';
  import { AppModule } from './app.module';
  import * as dotenv from 'dotenv';
  import * as path from 'path';
  
  async function bootstrap() {
    const env = process.env.NODE_ENV || 'local';
    dotenv.config({ path: path.join(__dirname, `../environment/${env}.env`) });
  
    const app = await NestFactory.create(AppModule);
    await app.listen(process.env.PORT || 3000);
  }
  bootstrap();
  

5. 运行命令示例 #

• 本地开发启动：nx serve be-license-server --configuration=local
• 开发环境构建：nx build be-license-server --configuration=development
• 生产环境启动：nx serve be-license-server --configuration=production

内容的提问来源于stack exchange，提问作者Elias Salom