Adding .env & ConfigModule — Teaching Your App to Read Sticky Notes 📝

So, you’ve got secrets to tell your app — like database passwords, API keys, and the name of your favorite pizza topping 🍕. But hardcoding them? That’s a one-way ticket to 💥 chaos.

Enter the .env file: the Post-it note of your application's memory.

🧙‍♂️ Step 1: Install the Magic Tools

NestJS doesn’t come with config powers out-of-the-box, so let’s install the helpers:

npm install --save @nestjs/config

if you're one of those yarn people 🧶)

yarn add @nestjs/config

📁 Step 2: Create Your .env File

In the root of your project, whisper your secrets:

PORT=3000
DATABASE_URL=postgres://your_db_user:your_db_pass@localhost:5432/mydb
JWT_SECRET=shhh_dont_tell_anyone

Yes, it’s basically your app’s diary 📖. Keep it out of Git with:

echo ".env" >> .gitignore

🧩 Step 3: Load Config in AppModule

Time to let NestJS read those sticky notes:

// app.module.ts
import { Module } from "@nestjs/common";
import { ConfigModule } from "@nestjs/config";

@Module({
  imports: [
    ConfigModule.forRoot({
      isGlobal: true, // so you don’t have to import it everywhere
    }),
  ],
})
export class AppModule {}

And poof 💨 — your app can now whisper its own secrets!

📚 Step 4: Use It Anywhere (Like a Pro)

// any.service.ts
import { Injectable } from "@nestjs/common";
import { ConfigService } from "@nestjs/config";

@Injectable()
export class AnyService {
  constructor(private configService: ConfigService) {
    const dbUrl = this.configService.get<string>("DATABASE_URL");
    console.log(`Connecting to: ${dbUrl}`);
  }
}

Like magic 🪄, your app now reads .env without spilling the beans.

🛑 Bonus Tip: Validate Your Env Vars Like a Strict Teacher ✍️

You can even use a schema validator like Joi to say:

"Hey app, I dare you to run without a JWT_SECRET!"

But we’ll save that for the "Advanced Config" chapter.

💡 TL;DR

Task	Command/Code
Install config	npm install @nestjs/config
Add .env file	PORT=3000, etc.
Load globally	ConfigModule.forRoot({ isGlobal: true })
Use anywhere	configService.get('KEY')