What are the different ways to configure properties in a Spring Boot application?

Category : Interview Questions | Sub Category : Spring Boot Interview Questions | By Prasad Bonam Last updated: 2023-08-04 00:22:04 Viewed : 331

What are the different ways to configure properties in a Spring Boot application?

In a Spring Boot application, you can configure properties using various methods. Spring Boot supports different sources for externalizing configuration, allowing you to customize your applications behavior without modifying the code. Here are the different ways to configure properties in a Spring Boot application:

1. application.properties or application.yml: The most common and straightforward way to configure properties is by using the application.properties (for properties format) or application.yml (for YAML format) files. These files are typically placed in the src/main/resources folder.

   Example (application.properties):

   bashCopy code
   # Set server port
   server.port=8080
   
   # Set database connection properties
   spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase
   spring.datasource.username=root
   spring.datasource.password=secret
   

   Example (application.yml):

   yamlCopy code
   # Set server port
   server:
     port: 8080
   
   # Set database connection properties
   spring:
     datasource:
       url: jdbc:mysql://localhost:3306/mydatabase
       username: root
       password: secret# Set server port
   server:
     port: 8080
   
   # Set database connection properties
   spring:
     datasource:
       url: jdbc:mysql://localhost:3306/mydatabase
       username: root
       password: secret

2. Command-Line Arguments: You can override properties defined in the application.properties or application.yml files by passing command-line arguments when running the application. Command-line arguments have higher precedence than properties files.

   Example:

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   java -jar my-application.jar --server.port=9090
   

3. Environment Variables: Spring Boot allows you to use environment variables to configure properties. Environment variables can be set in the operating system or using container orchestration tools like Docker or Kubernetes.

   Example:

   arduinoCopy code
   export SERVER_PORT=8080
   

4. System Properties: Spring Boot automatically binds system properties to configuration properties.

   Example (as command-line argument):

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   java -jar my-application.jar -Dserver.port=9090
   

5. Properties from JNDI: If you deploy your Spring Boot application to a Java EE container, properties can be configured using Java Naming and Directory Interface (JNDI) resources.

6. Properties from Profiles: You can define different property values for different environments or profiles. For example, you can have separate application.properties files for "development" and "production" profiles.

   Example:

   • application-dev.properties:

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     server.port=8080
     spring.datasource.url=jdbc:mysql://localhost:3306/devdb
     

   • application-prod.properties:

     bashCopy code
     server.port=9090
     spring.datasource.url=jdbc:mysql://prod-db-server:3306/proddb
     

   You can activate a specific profile using the spring.profiles.active property.

These are the main ways to configure properties in a Spring Boot application. Depending on your use case and deployment environment, you can choose the most suitable method for externalizing configuration.