How to implement and package your own Spring Boot Starter to extend the application's functionality?

To create your own Spring Boot Starter, follow these steps:

1. Create a separate Maven/Gradle module with dependencies and code that extend functionality.

2. Implement auto-configuration using a class annotated with @Configuration and @ConditionalOn... for conditional inclusion.

3. Add a spring.factories file in the src/main/resources/META-INF/ folder specifying the auto-configuration class:

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.starter.YourAutoConfiguration

4. Publish the artifact to a repository (e.g., Maven Central or internal).

5. Use the Starter in other projects by adding the dependency.

Example of auto-configuration:

@Configuration
@ConditionalOnClass(SomeLibrary.class)
@EnableConfigurationProperties(YourProperties.class)
public class YourAutoConfiguration {

    @Bean
    public YourService yourService(YourProperties props) {
        return new YourService(props.getConfigValue());
    }
}

This way, Spring Boot will automatically include your Starter and configure the necessary beans when the dependency is added.