Why deployment configuration matters in NextJS - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the deployment environment variable in Next.js.

NextJS

const environment = process.env.[1];

Drag options to blanks, or click blank then click option'

ANEXT_PUBLIC_KEY

BPORT

CAPI_URL

DNODE_ENV

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable for port or API URL instead of environment mode.

The NODE_ENV variable tells Next.js the deployment environment like development or production.

2fill in blank

medium

Complete the code to import the Next.js configuration file.

NextJS

import [1] from 'next/config';

Drag options to blanks, or click blank then click option'

AnextConfig

BgetConfig

Cconfig

DuseConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that is not a function.

The function getConfig is used to access Next.js runtime configuration.

3fill in blank

hard

Fix the error in accessing the public runtime configuration in Next.js.

NextJS

const { publicRuntimeConfig } = [1]();

Drag options to blanks, or click blank then click option'

AgetConfig

Bconfig

CuseConfig

DnextConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to destructure from a variable instead of calling the function.

You must call the getConfig function to get the runtime configuration object.

4fill in blank

hard

Fill both blanks to correctly set environment variables in Next.js deployment.

NextJS

module.exports = {
  env: {
    [1]: process.env.[2]
  }
};

Drag options to blanks, or click blank then click option'

AAPI_URL

BNEXT_PUBLIC_API_URL

CAPI_SECRET

DDATABASE_URL

Attempts:

3 left

💡 Hint

Common Mistakes

Using secret keys as public variables.

Not prefixing public variables correctly.

Public environment variables in Next.js start with NEXT_PUBLIC_. Here, NEXT_PUBLIC_API_URL is set from process.env.API_URL.

5fill in blank

hard

Fill all three blanks to create a Next.js server action that uses environment variables.

NextJS

export async function handler(req, res) {
  const apiKey = process.env.[1];
  const response = await fetch(process.env.[2] + '/data', {
    headers: { 'Authorization': `Bearer ${apiKey}` }
  });
  const data = await response.[3]();
  res.status(200).json(data);
}

Drag options to blanks, or click blank then click option'

AAPI_SECRET_KEY

BAPI_URL

Cjson

DfetchData

Attempts:

3 left

💡 Hint

Common Mistakes

Using public keys for secret data.

Calling wrong response parsing methods.

The server action reads the secret key API_SECRET_KEY and the base URL API_URL. It fetches data and parses it as JSON.

Practice

1. Why is deployment configuration important in a Next.js application?

easy

A. It disables all security features by default.

B. It changes the app's color scheme automatically.

C. It only affects the app's local development environment.

D. It controls how the app runs on the server and connects to services.

Solution

1. Step 1: Understand deployment configuration role

   Deployment configuration sets how the app behaves on the server, including connections and performance.

2. Step 2: Compare options

   Only It controls how the app runs on the server and connects to services. correctly describes deployment configuration's purpose; others are unrelated or incorrect.

3. Final Answer:

   It controls how the app runs on the server and connects to services. -> Option D

4. Quick Check:

   Deployment config = server behavior control [OK]

Hint: Think where your app runs and what config controls there [OK]

Common Mistakes:

• Confusing deployment config with UI settings
• Assuming it only affects local development
• Ignoring security and performance roles

2. Which of the following is the correct way to specify an environment variable in Next.js deployment?

easy

A. Set variables in next.config.js under env property.

B. Write variables directly inside a React component.

C. Use a CSS file to store environment variables.

D. Declare variables only in package.json scripts.

Solution

1. Step 1: Identify environment variable setup in Next.js

   Next.js uses next.config.js with an env property to define environment variables for deployment.

2. Step 2: Eliminate incorrect options

   Options A, C, and D do not follow Next.js patterns for environment variables.

3. Final Answer:

   Set variables in next.config.js under env property. -> Option A

4. Quick Check:

   Env vars in next.config.js = correct [OK]

Hint: Remember env vars go in next.config.js, not in components [OK]

Common Mistakes:

• Placing env vars inside React components
• Trying to store env vars in CSS or package.json
• Not using next.config.js for deployment env vars

3. Given this next.config.js snippet:

module.exports = {
  reactStrictMode: true,
  env: { API_URL: 'https://api.example.com' }
};

What will process.env.API_URL output in the deployed app?

medium

A. An error will occur

B. undefined

C. 'https://api.example.com'

D. 'http://localhost:3000'

Solution

1. Step 1: Check env variable definition

   API_URL is set to 'https://api.example.com' in next.config.js env property.

2. Step 2: Understand process.env usage in Next.js

   In deployment, process.env.API_URL reads the value from next.config.js env, so it outputs the URL string.

3. Final Answer:

   'https://api.example.com' -> Option C

4. Quick Check:

   process.env.API_URL = 'https://api.example.com' [OK]

Hint: Env vars in next.config.js are available via process.env [OK]

Common Mistakes:

• Expecting undefined if not set in .env files
• Confusing local and deployment values
• Assuming process.env is empty in deployment

4. You deployed a Next.js app but it crashes with an error about missing environment variables. What is the most likely cause?

medium

A. You used the wrong React version in package.json.

B. You forgot to set environment variables in the deployment platform.

C. You did not import React in your components.

D. You used CSS variables instead of JavaScript variables.

Solution

1. Step 1: Analyze error cause

   Missing environment variables error usually means deployment platform lacks required env vars.

2. Step 2: Check other options

   Options B, C, and D are unrelated to environment variable errors.

3. Final Answer:

   You forgot to set environment variables in the deployment platform. -> Option B

4. Quick Check:

   Missing env vars = not set on deployment [OK]

Hint: Check deployment platform env vars first when app crashes [OK]

Common Mistakes:

• Blaming React version for env var errors
• Forgetting to configure deployment environment
• Confusing CSS variables with env vars

5. You want to deploy a Next.js app that uses a private API key. Which deployment configuration practice best protects this key?

hard

A. Store the API key in environment variables on the deployment server and access it only in server-side code.

B. Hardcode the API key inside React components for easy access.

C. Include the API key in the public next.config.js env property so client can use it.

D. Put the API key in a CSS file to hide it from JavaScript.

Solution

1. Step 1: Understand security for API keys

   Private keys must not be exposed to client-side code to prevent leaks.

2. Step 2: Choose secure deployment config

   Storing keys in environment variables on the server and using them only server-side keeps them safe.

3. Step 3: Eliminate unsafe options

   Hardcoding or exposing keys in client-accessible config or CSS is insecure.

4. Final Answer:

   Store the API key in environment variables on the deployment server and access it only in server-side code. -> Option A

5. Quick Check:

   Private keys stay server-side only [OK]

Hint: Keep secrets server-side in env vars, never expose to client [OK]

Common Mistakes:

• Exposing API keys in client code
• Hardcoding secrets in components
• Misusing next.config.js env for private keys