What should be in the configuration file of a Spring Boot application?

The configuration file of a Spring Boot application (usually application.properties or application.yml) should specify the main parameters necessary for starting and configuring the application:

• Server port (server.port)
• Database connection settings (URL, username, password, driver)
• Logging configuration
• Security parameters (e.g., authentication settings)
• Caching settings, if used
• External services and API configuration

Example application.yml:

server:
  port: 8080
spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/mydb
    username: user
    password: pass
  jpa:
    hibernate:
      ddl-auto: update
logging:
  level:
    root: INFO