Spring Boot Application Properties and YAML Configuration

In a Spring Boot application, you can configure various settings using either application.properties or application.yml files. These files allow you to specify application-wide settings such as database configurations, server settings, and custom properties.

1. Application Properties

The application.properties file uses simple key-value pairs, which is easy to read and widely used in Spring Boot.

Example: application.properties

server.port=8080

spring.datasource.url=jdbc:mysql://localhost:3306/mydb

spring.datasource.username=root

spring.datasource.password=rootpassword

logging.level.org.springframework.web=DEBUG

In this example:

server.port sets the server port to 8080.

spring.datasource.url, spring.datasource.username, and spring.datasource.password define the database connection properties.

logging.level.org.springframework.web sets the log level for web-related components.

2. Application YAML (YAML Configuration)

The application.yml file is a more structured configuration format that uses indentation to represent hierarchy.

Example: application.yml

server:

  port: 8080

spring:

  datasource:

    url: jdbc:mysql://localhost:3306/mydb

    username: root

    password: rootpassword

logging:

  level:

    org.springframework.web: DEBUG

In this example:

The structure is similar to the application.properties file, but YAML uses indentation to define nested properties.

The server.port and spring.datasource sections are nested under their respective keys.

Which to Use?

application.properties is simpler and better for quick configurations.

application.yml is more structured, better for complex configurations, and more readable when dealing with nested properties.

Both formats work the same way in Spring Boot, and you can choose whichever one suits your needs better.

Simple Example: Database Configuration

Let's say you want to configure a database connection.

Using application.properties:

spring.datasource.url=jdbc:mysql://localhost:3306/mydb

spring.datasource.username=root

spring.datasource.password=rootpassword

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

Using application.yml:

spring:

  datasource:

    url: jdbc:mysql://localhost:3306/mydb

    username: root

    password: rootpassword

    driver-class-name: com.mysql.cj.jdbc.Driver

Both configurations are equivalent. You can pick the one that best fits your team's preferences or project requirements.