Spring Boot Externalized Configuration and Profiles 3

Question 1

What happens if you set spring.profiles.active=dev,test simultaneously?

Accepted Answer

Both profiles are activated and their configs merged

Answer

Multiple profiles can be active at once; Spring Boot loads all matching profile-specific files and merges them.

Question 2

Which Spring Boot class provides programmatic access to which profiles are currently active?

Accepted Answer

Environment

Answer

The Environment interface exposes getActiveProfiles() and getDefaultProfiles() methods for programmatic profile inspection.

Question 3

What is the purpose of spring.profiles.default?

Accepted Answer

It specifies profiles activated when no active profiles are set

Answer

spring.profiles.default specifies which profiles are active when no profiles are explicitly activated.

Question 4

Which YAML structure activates a properties block only for the 'prod' profile in a single application.yml?

Accepted Answer

spring:
  config:
    activate:
      on-profile: prod

Answer

In Spring Boot 2.4+, spring.config.activate.on-profile within a YAML document block restricts that block to a specific profile.

Question 5

How does @ConfigurationProperties differ from @Value for configuration binding?

Accepted Answer

@ConfigurationProperties binds an entire prefix to a POJO; @Value injects a single property

Answer

@ConfigurationProperties maps all properties under a prefix to fields in a class, whereas @Value injects individual property values.

Spring Boot Practice Test