Environment variables in NestJS - Mini Project: Build & Apply

Using Environment Variables in NestJS

📖 Scenario: You are building a simple NestJS application that needs to use environment variables to configure its behavior. Environment variables help keep sensitive data like API keys or configuration settings outside your code.

🎯 Goal: Learn how to set up environment variables in a NestJS project and access them inside a service.

📋 What You'll Learn

Create a .env file with specific variables

Configure the ConfigModule to load environment variables

Inject ConfigService to read environment variables

Use environment variables inside a service method

💡 Why This Matters

🌍 Real World

Environment variables keep sensitive data and configuration outside code, making apps safer and easier to configure for different environments like development and production.

💼 Career

Knowing how to use environment variables is essential for backend developers working with NestJS or any server-side framework to manage configuration securely and flexibly.

1

Create a .env file with variables

Create a file named .env in the root folder with these exact lines:
API_KEY=12345
PORT=3000

NestJS

# Create a .env file with API_KEY=12345 and PORT=3000

Need a hint?

The .env file should be plain text with key=value pairs, no quotes.

2

Configure ConfigModule to load .env

In app.module.ts, import ConfigModule from @nestjs/config and add ConfigModule.forRoot() to the imports array inside @Module.

NestJS

import { Module } from '@nestjs/common';
// Import ConfigModule here

@Module({
  imports: [
    // Add ConfigModule.forRoot() here
  ],
})
export class AppModule {}

Need a hint?

ConfigModule.forRoot() loads environment variables automatically.

3

Inject ConfigService in a service

Create a service named AppService with a constructor that injects ConfigService from @nestjs/config. Store it in a private readonly variable called configService.

NestJS

import { Injectable } from '@nestjs/common';
// Import ConfigService here

@Injectable()
export class AppService {
  // Inject ConfigService in constructor
  constructor() {
    // Your code here
  }
}

Need a hint?

Use dependency injection to get ConfigService instance.

4

Use environment variables inside a method

Add a method getApiKey() inside AppService that returns the value of the environment variable API_KEY using this.configService.get('API_KEY').

NestJS

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

@Injectable()
export class AppService {
  constructor(private readonly configService: ConfigService) {}

  // Add getApiKey method here
}

Need a hint?

Use ConfigService's get method to read environment variables.