Spring Boot provides externalized configuration so that you can use the same code in different environments (for example, the local environment and the Docker environment). We are using YAML files for configuration, which is preferred over using the properties file. Then, you can make use of the @Value annotation to read properties in your code with the POST /actuator/refresh call, or use the object of the class that's annotated with @ConfigurationProperties. Spring Boot's externalized configuration resolves one problem of having different properties for different environments and allows us to use different environments without making any changes.

The next problem is how to make a change in a property on the fly while keeping all the configuration for different environments in a single place. To achieve more control over configuration management—as in what to keep, what to remove, and what to change—centralized configuration tools could be helpful. There are many tools available, such as Spring Cloud Config, Zookeeper, and Consul. We'll implement centralized configuration using Spring Cloud Config.