Managing Multiple External Configuration Files in Spring Boot: Organizing Your Application's Configuration Efficiently

 Spring Boot provides a convenient way to manage external configuration through properties files. By default, Spring Boot uses the application.properties file to load the configuration. However, you can also use multiple external configuration files to separate different configuration concerns.

To use multiple external configuration files in Spring Boot, you can follow these steps:

1. Create separate properties files for each configuration concern. For example, you might have database.properties, email.properties, and logging.properties.

2. Place these properties files in a location where Spring Boot can find them. By default, Spring Boot searches for properties files in the following locations (in the listed order):

   • The config folder in the current directory.
   • The current directory.
   • A classpath /config package.
   • The classpath root.

   You can also specify custom locations using the spring.config.location property (e.g., spring.config.location=classpath:/custom-config/).

3. In each properties file, specify the configuration properties relevant to that concern. For example, in database.properties, you might have properties like spring.datasource.url, spring.datasource.username, and spring.datasource.password.

4. When running your Spring Boot application, Spring Boot automatically loads all the properties from the relevant configuration files and applies them to your application's context.

It's important to note that Spring Boot applies properties in a specific order, and properties defined in files with higher precedence will override those defined in files with lower precedence. The precedence order, from highest to lowest, is as follows:

• Command line arguments
• SPRING_APPLICATION_JSON environment variable
• Java System properties (-D command line arguments)
• OS environment variables
• application-{profile}.properties or application-{profile}.yml
• application.properties or application.yml

By following these steps, you can effectively manage multiple external configuration files in a Spring Boot application, separating concerns and organizing your configuration more efficiently.