Profile-based configuration in Spring Boot - Mini Project: Build & Apply

Profile-based configuration in Spring Boot

📖 Scenario: You are building a Spring Boot application that needs to behave differently in development and production environments. You want to use profile-based configuration to switch settings easily.

🎯 Goal: Create a Spring Boot application that uses application-dev.properties and application-prod.properties files to load different greeting messages based on the active profile.

📋 What You'll Learn

Create a base application.properties file

Create application-dev.properties with a greeting message

Create application-prod.properties with a different greeting message

Create a Spring Boot main class that reads the greeting message from properties

Use the @Value annotation to inject the greeting message

Use spring.profiles.active to switch between profiles

💡 Why This Matters

🌍 Real World

Profile-based configuration is used to manage different settings for development, testing, and production environments without changing code.

💼 Career

Understanding profile-based configuration is essential for backend developers working with Spring Boot to deploy applications safely and efficiently.

1

Create base application.properties and dev profile properties

Create a file named application.properties with no content. Then create application-dev.properties containing the line app.greeting=Hello from Development!.

Spring Boot

# Create application.properties (empty) and application-dev.properties with app.greeting=Hello from Development!

Need a hint?

The application.properties file can be empty. The application-dev.properties file must contain the exact line app.greeting=Hello from Development!.

2

Create prod profile properties with a different greeting

Create application-prod.properties containing the line app.greeting=Hello from Production!.

Spring Boot

# Add application-prod.properties with app.greeting=Hello from Production!

Need a hint?

Make sure the application-prod.properties file contains the exact line app.greeting=Hello from Production!.

3

Create Spring Boot main class with greeting injection

Create a Spring Boot main class named ProfileDemoApplication in package com.example.demo. Use @Value("${app.greeting}") to inject the greeting into a String greeting field. Add a @RestController with a @GetMapping("/") method that returns the greeting string.

Spring Boot

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class ProfileDemoApplication {

    // Your code here
}

Need a hint?

Use @Value("${app.greeting}") to inject the greeting. Create a nested @RestController class with a @GetMapping("/") method returning the greeting.

4

Set active profile and run the application

In application.properties, add the line spring.profiles.active=dev to activate the dev profile. This will make the application use the dev greeting message when running.

Spring Boot

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class ProfileDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(ProfileDemoApplication.class, args);
    }

    @RestController
    class GreetingController {

        @Value("${app.greeting}")
        private String greeting;

        @GetMapping("/")
        public String greet() {
            return greeting;
        }
    }
}

# Add spring.profiles.active=dev to application.properties

Need a hint?

Add the exact line spring.profiles.active=dev to application.properties to activate the dev profile.