Here’s an example of how auto-configuration works in Spring Boot with the JDBC (Java Database Connectivity) starter:

When you include the “spring-boot-starter-jdbc” dependency in your Spring Boot application, Spring Boot automatically scans the classpath and detects the presence of the JDBC driver for your database, such as MySQL or PostgreSQL.

If JDBC drive is present then Spring Boot can also automatically configures a DataSource bean with default settings, such as connection pool properties, database URL, username, and password. It also configures a JdbcTemplate bean for simplified database operations.

Spring Boot provides default configuration properties for the DataSource bean, such as “spring.datasource.url”, “spring.datasource.username”, and “spring.datasource.password”. These properties can be specified in the application.properties or application.yml file, and Spring Boot automatically binds them to the corresponding DataSource bean.

If you need to customize the default settings, you can specify your own configuration properties or provide custom configuration classes. For example, you can override the default DataSource settings with your own database properties, or you can provide a custom DataSource bean with specific configuration settings.

Similarly, auto-configuration works with other components in Spring Boot, such as Kafka and Microservices. For example, when you include the “spring-kafka” starter, Spring Boot automatically configures Kafka-related beans, such as KafkaTemplate and KafkaListenerContainer, based on the presence of the Kafka client library.

Similarly, when you include the “spring-cloud-starter-netflix-eureka-client” starter for building Microservices with Eureka, Spring Boot automatically configures a EurekaClient bean for service discovery and registration with Eureka server.

Overall, auto-configuration in Spring Boot simplifies the configuration process for various components, reduces boilerplate code, and allows developers to quickly set up fully functional applications with sensible default settings.