Default Configuration in Spring Boot

Introduction

Objective

Examples

Overriding

Summary

What is Default Configuration in a Spring Boot Application ?

Default configuration in Spring Boot refers to the set of configurations that Spring Boot applies to an application by default, without any additional configuration required from the developer.

It is a feature that allows developers to quickly and easily create Spring applications with minimal setup.

These default configurations are based on various factors such as the classpath, the environment, and the dependencies included in the project.

Objective:

Spring Boot follows the convention-over-configuration approach where it provides sensible default configurations for various components such as web servers, database connectivity, security, logging, etc. based on the dependencies added to the project. This means that a developer can create a fully functional application without writing much configuration code.

Examples:

Here are some examples of default configurations in Spring Boot:

• Servlet container configuration: Spring Boot configures an embedded servlet container by default, so you can run your web application without having to install and configure an external container like Tomcat or Jetty.
• Logging configuration: Spring Boot provides default logging configuration based on the Logback framework, which is included in the classpath by default. You can customize the logging configuration by providing your own logback.xml or logback-spring.xml file.
• Database configuration: If you include a database driver on the classpath, Spring Boot will attempt to configure a DataSource and JdbcTemplate automatically. You can also use Spring Data JPA or Spring Data JDBC for more advanced database operations.
• Configuration properties: Spring Boot provides a set of default configuration properties that you can use to configure your application. For example, you can use 'server.port' to configure the server port, 'spring.datasource.url' to configure the database URL, and 'logging.level' to configure the logging level.
• Spring Boot Actuator: Spring Boot includes a set of default endpoints that provide useful information about your application, such as health status, metrics, and environment information. You can customize the actuator configuration by providing your own application.yml or 'application.properties' file.

How the Default Configuration Works ?

Suppose we have a simple Spring Boot application that we want to deploy to a server. We can start by creating a new Maven project and adding the following dependencies to our 'pom.xml' file:

Adding 'spring-boot-starter-web' dependency to the project, Spring Boot will automatically configure the embedded Tomcat server, servlet container, and the dispatcher servlet.

Similarly, Adding 'spring-boot-starter-data-jpa' dependency, Spring Boot will configure the data source, transaction manager, and entity manager factory.

How to Override Default Configurations ?

We can also override the default configuration provided by Spring Boot by creating our own configuration classes and properties files. For example, we could create a 'application.properties' file in our project’s 'src/main/resources' directory and add the following property:

This would change the default port that Spring Boot uses to start the web server.

Summary:

In summary, default configuration in Spring Boot provides developers with a convenient way to quickly create and deploy Spring applications without having to configure everything manually. The framework automatically configures the application based on sensible defaults, but also allows for easy customization through the use of configuration classes and properties files.