Spring Boot Profiles – Detailed Explanation

Spring Boot Profiles allow you to define different configurations for different environments such as development, testing, staging, and production.

What are Spring Boot Profiles?

Profiles help you run the same codebase with different configurations without changing the application code.

• dev – Development environment
• test – Testing environment
• stage – Staging environment
• prod – Production environment

Why Do We Need Profiles?

Profiles provide clean separation, safer deployments, and easy environment switching.

How Spring Boot Profiles Work

Spring Boot loads configuration based on:

1. Active profile
2. Default profile
3. Profile-specific configuration files

Common configuration files:

    application.properties
    application-dev.properties
    application-test.properties
    application-prod.properties
    

1. Defining Profiles Using Properties Files

Default Configuration

    # application.properties
    spring.application.name=my-app
    

Development Profile

    # application-dev.properties
    server.port=8081
    spring.datasource.url=jdbc:mysql://localhost:3306/devdb
    logging.level.root=DEBUG
    

Production Profile

    # application-prod.properties
    server.port=8080
    spring.datasource.url=jdbc:mysql://prod-server:3306/proddb
    logging.level.root=ERROR
    

2. Activating a Profile

Using application.properties

    spring.profiles.active=dev
    

Using JVM Argument (Recommended for Production)

    java -jar app.jar --spring.profiles.active=prod
    

Using Environment Variable

    export SPRING_PROFILES_ACTIVE=test
    

Using IDE (VM Options)

    -Dspring.profiles.active=dev
    

3. Using @Profile Annotation

You can enable or disable beans based on active profiles.

    @Service
    @Profile("dev")
    public class DevEmailService implements EmailService {
    }
    

    @Service
    @Profile("prod")
    public class ProdEmailService implements EmailService {
    }
    

Only the bean matching the active profile will be loaded.

4. Using @Profile with Configuration Classes

    @Configuration
    @Profile("test")
    public class TestConfig {
    
        @Bean
        public DataSource dataSource() {
            return new EmbeddedDatabaseBuilder()
                    .setType(EmbeddedDatabaseType.H2)
                    .build();
        }
    }
    

5. Default Profile

If no profile is explicitly set, Spring uses the default profile.

    @Profile("default")
    @Component
    public class DefaultService {
    }
    

6. Multiple Active Profiles

Spring Boot supports activating multiple profiles at once.

    --spring.profiles.active=dev,swagger
    

Spring loads configuration files for all active profiles. The last profile overrides conflicting values.

7. Profile-Specific YAML Configuration

    spring:
      profiles:
        active: dev
    
    ---
    spring:
      config:
        activate:
          on-profile: dev
    server:
      port: 8081
    
    ---
    spring:
      config:
        activate:
          on-profile: prod
    server:
      port: 8080
    

8. Profile-Based Logging

    # application-dev.properties
    logging.level.root=DEBUG
    

    # application-prod.properties
    logging.level.root=ERROR
    

9. Profiles with Spring Boot Tests

    @SpringBootTest
    @ActiveProfiles("test")
    public class UserServiceTest {
    }
    

This loads the application-test.properties configuration.

10. Common Use Cases

• Database configurations
• Logging levels
• Security rules
• Mock vs real services
• Feature toggles

11. Best Practices

• Do not hard-code credentials
• Use environment variables in production
• Use @Profile for beans, not business logic
• Avoid too many profiles
• Prefer YAML for complex configuration

12. Interview Questions (Quick)

• Can we have multiple active profiles? Yes
• What is the default profile? default
• Can profiles control bean loading? Yes, using @Profile
• Spring vs Spring Boot profiles? Same concept, Boot simplifies usage

13. Real-World Analogy

• Same car
• Different driving modes (Eco, Sport, Test)

Summary

Spring Boot profiles are essential for managing environment-specific configurations. They make applications safer, cleaner, and easier to deploy across multiple environments.