Yml config files "Inheritance" with Spring boot

Here is my solution.

Assume application.yml:

spring:
  profiles: default-server-config

server:
  port: 9801
  servlet:
    context-path: '/ctp'

If I want use default-server-config profile, and use port 8080 in my application-dev.yml

application-dev.yml:

spring:
  profiles:
    include:
      - default-server-config
      - dev-config

---
spring:
  profiles: dev-config
  
server:
  port: 8080

Then -Dspring.profiles.active=dev

Yes, application.yml file has higher precedence over any application-{profile}.yml file. Properties from profile specific yml file will override values from the default application.yml file and properties that do not exist in profile specific yml file will be loaded from the default one. It applies to .properties files as well as to bootstrap.yml or bootstrap.properties.

Spring Boot documentation mentions it in 72.7 Change configuration depending on the environment paragraph:

In this example the default port is 9000, but if the Spring profile ‘development’ is active then the port is 9001, and if ‘production’ is active then it is 0.

The YAML documents are merged in the order they are encountered (so later values override earlier ones).

To do the same thing with properties files you can use application-${profile}.properties to specify profile-specific values.