Spring Boot Profiles - Application Configuration made easy

This guide will introduce you to profiles and help you understand how to use profiles with the various application configuration options that are present in Spring Boot.

You will learn

What is application configuration?
What is a profile?
How do you define beans for a specific profile?
How do you create application configuration for a specific profile?
How do you have different configuration for different environments?

Need for Application Configuration

Configuration for applications vary from one environment to another

You would want to connect to a different database or queues
You would want to connect with different services
You would want to configure less logging in production
You might want to have different custom configuration

Need for Profiles

Enterprise application development is complex. You have multiple environments

Dev
QA
Stage
Production

You want to have different application configuration in each of the environments.

Profiles help to have different application configuration for different environments.

Spring and Spring Boot provide features where you can specify

What is the configuration for various environments in different profiles?
Set the active profile for a specific environment.

Spring Boot would pick up the application configuration based on the active profile that is set in a specific environment.

Project Code Structure

Following screen shot shows the structure of the project we will create.

A few details:

SpringBootTutorialBasicsConfigurationApplication.java - The Spring Boot Application class generated with Spring Initializer. This class acts as the launching point for application. In this example, a few profile based beans are also created in the Application class.
pom.xml - Contains all the dependencies needed to build this project.
BasicConfiguration.java - We will use this component to define application configuration using @ConfigurationProperties
WelcomeResource.java - Example of a resource using @Value
application.properties - Configuration for application. Active profile is set in application.properties in this example
application-dev.properties - Configuration Overrides for dev profile
application-prod.properties - Configuration Overrides for prod profile

Tools you will need

Maven 3.0+ is your build tool
Your favorite IDE. We use Eclipse.
JDK 1.8+

Complete Maven Project With Code Examples

Our Github repository has all the code examples - https://github.com/in28minutes/spring-boot-examples/tree/master/spring-boot-tutorial-basics-configuration

Bootstrapping with Spring Initializr

Spring Initializr http://start.spring.io/ is great tool to bootstrap your Spring Boot projects.

As shown in the image above, following steps have to be done

Launch Spring Initializr and choose the following
- Choose com.in28minutes.springboot.tutorial.basics.application.configuration as Group
- Choose spring-boot-tutorial-basics-configuration as Artifact
- Choose following dependencies
  - Web
  - DevTools
Click Generate Project.
Import the project into Eclipse. File -> Import -> Existing Maven Project.

Set up a Quick Example to illustrate Profiles

Lets create a simple resource to expose application configuration using @Value.

@RestController
public class WelcomeResource {

	@Value("${welcome.message}")
	private String welcomeMessage;

	@GetMapping("/welcome")
	public String retrieveWelcomeMessage() {
		// Complex Method
		return welcomeMessage;
	}
}

Value for welcome message can be configured in application.properties.

welcome.message=Welcome message from property file! Welcome to in28Minutes

When you launch http://localhost:8080/welcome, you would see a page with this message

Welcome message from property file! Welcome to in28Minutes

Let’s define another simple resource specifying application configuration using @ConfigurationProperties.

@Component
@ConfigurationProperties("basic")
public class BasicConfiguration {
    private boolean value;
    private String message;
    private int number;

    //GETTERS AND SETTERS
}

We would need to use the BasicConfiguration in a service to expose the values

@Autowired
private BasicConfiguration configuration;

@RequestMapping("/dynamic-configuration")
public Map dynamicConfiguration() {
    // Not the best practice to use a map to store differnt types!
    Map map = new HashMap();
    map.put("message", configuration.getMessage());
    map.put("number", configuration.getNumber());
    map.put("key", configuration.isValue());
    return map;
}

When you browse to http://localhost:8080/dynamic-configuration, you see the following response.

{"number":100,"message":"Dynamic Message","key":true}

The above example is explained step by step in more detail in the Application Configuration article - http://www.springboottutorial.com/spring-boot-application-configuration

Using Profiles to configure environment specific configuration

Profile is nothing but a key to identify an environment.

In this example, we will use two profiles

dev
prod

The default application configuration is present in application.properties. Let’s consider an example.

application.properties

logging.level.org.springframework.web.servlet: DEBUG
app.name=in28Minutes
welcome.message=Welcome message from property file! Welcome to ${app.name}

basic.value= true
basic.message= Dynamic Message
basic.number= 100

We would want to customize the application.properties for DEV profile. We would need to create a file with name application-dev.properties and override the properties that we would want to customize.

application-dev.properties

welcome.message=Welcome message from property file! Welcome to ${app.name} in DEV

basic.message: Dynamic Message in DEV

Similarly you can configure properties for prod profile.

application-prod.properties

welcome.message=Welcome message from property file! Welcome to ${app.name} in Prod

basic.message: Dynamic Message in Prod

Setting Active Profile

Once you have profile specific configuration, you would need to set the active profile in an environment.

There are multiple ways of doing this

Using -Dspring.profiles.active=prod in VM Arguments
Use spring.profiles.active=prod in application.properties

In this example let’s set it in application.properties. Lets add another property to application.properties

spring.profiles.active=dev

When you restart the application, you would see that the dev profile is active.

otTutorialBasicsConfigurationApplication : The following profiles are active: dev

Look at the response from services

http://localhost:8080/welcome

Welcome message from property file! Welcome to in28Minutes in DEV

http://localhost:8080/dynamic-configuration

{"number":100,"message":"Dynamic Message in DEV","key":true}

You can see that the configuration for dev profile is being picked up by Spring Boot.

Configuring Profile Specific Beans

You can take this one step further and configure profile specific beans that are created only in specific profiles.

Let’s add this to SpringBootTutorialBasicsConfigurationApplication.java

	@Profile("dev")
	@Bean
	public String devBean() {
		return "dev";
	}

	@Profile("qa")
	@Bean
	public String qaBean() {
		return "qa";
	}

	@Profile("prod")
	@Bean
	public String prodBean() {
		return "prod";
	}

Using @Profile annotation we can indicate the active profile in which a specific bean should be created.

To test this let’s further enhance SpringBootTutorialBasicsConfigurationApplication.

Let’s print the name of all the beans that are loaded.

	public static void main(String[] args) {
		ApplicationContext applicationContext = SpringApplication
				.run(SpringBootTutorialBasicsConfigurationApplication.class, args);

		for (String name : applicationContext.getBeanDefinitionNames()) {
			System.out.println(name);
		}
	}

We are currently using dev profile

spring.profiles.active=dev

When you reload the application, you would see the following in the log

devBean

You would see that the devBean is created. However, the beans shown below are not created because those profiles are not active.

	@Profile("qa")
	@Bean
	public String qaBean() {
		return "qa";
	}

	@Profile("prod")
	@Bean
	public String prodBean() {
		return "prod";
	}

Complete Maven Project With Code Examples

Our Github repository has all the code examples - https://github.com/in28minutes/spring-boot-examples/tree/master/spring-boot-tutorial-basics-configuration