Read values from consul while bootstrap spring boot

I have question is there any way to retrieve certain values and inject them to bootstrap.yml while application is coming up.

I have configuration file like this:

spring:
  application:
    name: myApp

  cloud:
    consul:
      enabled: true
      host: localhost
      port: 8500
      config:
        enabled: true

  datasource:
    url: jdbc:oracle:thin:@localhost:1111:XXXX
    username: ${nameOfVariable1}
    password: ${nameOfVariable1}
    driver-class-name: oracle.jdbc.OracleDriver

For example, I need to configure embedded tomcat port, or DB credentials, I don't want to put it hardcoded in .yml properties file, instead I want to put some variable name in .yml so Spring will go and bring value from Consul. Is it possible?

You can use Spring Cloud Consul Config project that helps to load configuration into the Spring Environment during the special "bootstrap" phase.

3 steps:

1. add pom dependency: spring-cloud-starter-consul-config
2. enable consul config: spring.cloud.consul.config.enabled=true
3. add some config in consul kv in specific folder, such as key: config/testConsulApp/server.port, value:8081

and then start the sample web app, it will listen 8081.

more detail at spring cloud consul doc.

and demo code here