How to concat strings in application.yaml?

Question

I want to add two lines in a yaml file, or rather, I want the instance-id field to contain the result of adding the values of the port and name fields I tried using +, tried through various tags that I saw in similar questions, like !join, !concat (java says they don't exist). But nothing worked in the end. Is there a solution?

Example yaml (Sorry, i dont know how to load yaml here):

server:
  port: &port 62000
spring:
  application:
    name: &appname 'appname'
eureka:
  client:
    service-url:
      defaultZone: 'http://localhost:8081/eureka/'
  instance:
    instance-id: here should be *appname + ":" + *port (result appname:62000)

Answer 1

This won't work for YAML in general, but it will work in Spring Boot, since you can use Property Placeholders, and thus reference other properties from within a property value:

server:
  port: 62000
spring:
  application:
    name: 'appname'
eureka:
  client:
    service-url:
      defaultZone: 'http://localhost:8081/eureka/'
  instance:
    instance-id: ${spring.application.name}:${server.port}

This also works with environment variables, btw.

Answer 2

i can provide my application.yml file config for flyway, i think that, based on this code, you can achieve what you want

  flyway:
    url: jdbc:postgresql://${DATABASE_HOST}:${DATABASE_PORT}/${DATABASE_NAME}
    user: ${DATABASE_USER}
    password: ${DATABASE_PASSWORD}
    driver-class-name: org.postgresql.Driver
    baseline-on-migrate: true
    enabled: true
    validate-on-migrate: true
    baseline-version: 0
    default-schema: ${DATABASE_SCHEMA}

and you should remember, that this values must been provided by you, while running application, put them in a environment variables see a link!, or if you run integration tests, you can use @DynamicPropertySource public static void setUpDynamicPropertyValues(DynamicPropertyRegistry registry) { // registry.add("eureka.instance.instance-id", () -> "your instance-id here");

Answer 3

typically we don't have direct string concatenation or arithmetic operations like in some other languages. However, you can use YAML anchors and aliases to achieve something similar.