Compression and security headers in NestJS - Mini Project: Build & Apply

Compression and Security Headers in NestJS

📖 Scenario: You are building a simple NestJS server for a blog website. To improve performance and security, you want to add compression and security headers to your server responses.

🎯 Goal: Set up a NestJS application that uses middleware to compress responses and add security headers using Helmet.

📋 What You'll Learn

Create a basic NestJS application with a root module

Add compression middleware to compress HTTP responses

Add Helmet middleware to set security headers

Configure the middleware in the main application bootstrap

💡 Why This Matters

🌍 Real World

Web servers often use compression to reduce response size and security headers to protect users from common web vulnerabilities.

💼 Career

Understanding how to add middleware like compression and Helmet is essential for backend developers working with Node.js frameworks like NestJS to build secure and efficient web applications.

1

Create a basic NestJS application

Create a NestJS application by importing NestFactory from @nestjs/core and the root module AppModule from ./app.module. Then create an async function bootstrap that creates the app instance using NestFactory.create(AppModule).

NestJS

import { NestFactory } from '@nestjs/core';
import { AppModule } from './app.module';

async function bootstrap() {
  // Your code here
}

bootstrap();

Hint

Use NestFactory.create(AppModule) inside the bootstrap function to create the app.

2

Add compression middleware

Import compression from the compression package. Then, inside the bootstrap function, add the compression middleware to the app by calling app.use(compression()).

NestJS

import compression from 'compression';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  // Your code here
}

bootstrap();

Hint

Use app.use(compression()) to add compression middleware.

3

Add Helmet middleware for security headers

Import helmet from the helmet package. Then, inside the bootstrap function, add the Helmet middleware to the app by calling app.use(helmet()) after adding compression.

NestJS

import helmet from 'helmet';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(compression());
  // Your code here
}

bootstrap();

Hint

Use app.use(helmet()) to add security headers middleware.

4

Start the NestJS server

Inside the bootstrap function, after adding the middleware, start the server by calling await app.listen(3000) to listen on port 3000.

NestJS

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(compression());
  app.use(helmet());
  // Your code here
}

bootstrap();

Hint

Use await app.listen(3000) to start the server on port 3000.

Practice

1. What is the main purpose of using compression middleware in a NestJS application?

easy

A. To reduce the size of response data sent to clients

B. To add security headers to HTTP responses

C. To log incoming requests for debugging

D. To handle database connections efficiently

Solution

1. Step 1: Understand what compression middleware does

   The compression middleware compresses HTTP response bodies to reduce their size.

2. Step 2: Identify the effect on client-server communication

   Smaller response sizes mean faster data transfer and improved app speed.

3. Final Answer:

   To reduce the size of response data sent to clients -> Option A

4. Quick Check:

   Compression = smaller response size [OK]

Hint: Compression shrinks data sent to users for speed [OK]

Common Mistakes:

• Confusing compression with security features
• Thinking compression logs requests
• Assuming compression manages databases

2. Which of the following is the correct way to apply helmet middleware in a NestJS main.ts file?

easy

A. app.apply(helmet);

B. app.helmet();

C. helmet(app);

D. app.use(helmet());

Solution

1. Step 1: Recall the NestJS middleware usage pattern

   Middleware is applied using app.use() with the middleware function as argument.

2. Step 2: Check the syntax for helmet middleware

   The correct syntax is app.use(helmet()); to apply helmet with default settings.

3. Final Answer:

   app.use(helmet()); -> Option D

4. Quick Check:

   Middleware applied with app.use() [OK]

Hint: Use app.use() to add middleware like helmet [OK]

Common Mistakes:

• Calling helmet as a method on app
• Passing app as argument to helmet
• Using app.apply() which is invalid

3. Given this NestJS setup in main.ts:

import * as compression from 'compression';
import * as helmet from 'helmet';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(compression());
  app.use(helmet());
  await app.listen(3000);
}

What will be the effect on HTTP responses?

medium

A. No effect; middleware is not applied correctly

B. Responses will be compressed and have security headers added

C. Responses will only have security headers, no compression

D. Responses will only be compressed, no security headers

Solution

1. Step 1: Analyze middleware usage in the code

   Both compression() and helmet() are applied using app.use(), which is correct.

2. Step 2: Understand middleware effects

   Compression middleware compresses responses; helmet adds security headers.

3. Final Answer:

   Responses will be compressed and have security headers added -> Option B

4. Quick Check:

   Both compression and helmet applied = compressed + secure headers [OK]

Hint: Both middlewares applied means both effects present [OK]

Common Mistakes:

• Thinking only one middleware works at a time
• Assuming middleware needs special chaining
• Believing middleware is ignored without extra config

4. Identify the error in this NestJS main.ts snippet:

import helmet from 'helmet';

async function bootstrap() {
  const app = await NestFactory.create(AppModule);
  app.use(helmet);
  await app.listen(3000);
}

medium

A. helmet is not called as a function before passing to app.use

B. helmet should be imported with * as helmet from 'helmet'

C. app.listen should be called before app.use

D. NestFactory.create requires an options object

Solution

1. Step 1: Check how helmet middleware is passed

   Middleware functions must be called to return a function; here helmet is passed without parentheses.

2. Step 2: Confirm correct usage

   The correct usage is app.use(helmet()); to apply helmet middleware.

3. Final Answer:

   helmet is not called as a function before passing to app.use -> Option A

4. Quick Check:

   Middleware must be called: helmet() [OK]

Hint: Always call middleware functions before app.use [OK]

Common Mistakes:

• Passing middleware reference without calling it
• Importing helmet incorrectly but that still works with default export
• Calling app.listen before middleware setup

5. You want to add compression and security headers in a NestJS app but only compress responses larger than 1KB and disable the X-Powered-By header. Which setup achieves this?

hard

A. app.use(compression({ minSize: 1024 })); app.use(helmet({ hidePoweredBy: true }));

B. app.use(compression({ threshold: 1024 })); app.use(helmet.hidePoweredBy());

C. app.use(compression({ threshold: 1024 })); app.use(helmet({ hidePoweredBy: true }));

D. app.use(compression()); app.use(helmet({ disablePoweredBy: true }));

Solution

1. Step 1: Configure compression threshold correctly

   The compression middleware option to set minimum size is threshold, so { threshold: 1024 } means compress responses over 1KB.

2. Step 2: Disable X-Powered-By header using helmet option

   Helmet's option to hide this header is hidePoweredBy: true.

3. Final Answer:

   app.use(compression({ threshold: 1024 })); app.use(helmet({ hidePoweredBy: true })); -> Option C

4. Quick Check:

   Compression threshold + hidePoweredBy option [OK]

Hint: Use compression threshold and helmet hidePoweredBy option [OK]

Common Mistakes:

• Using wrong option name like minSize or disablePoweredBy
• Calling helmet.hidePoweredBy() which does not exist
• Not setting threshold causing all responses compressed