Configuring cloud-native applications using MicroProfile Config

MicroProfile Config (source code located at https://github.com/eclipse/microprofile-config) is the first specification created by the MicroProfile community. The concept of configuration has been around for a decade. You may recall in Chapter 1, Cloud-Native Application, we briefly discussed the Twelve-Factor App, in which the third factor III. Config (https://12factor.net/config) recommends that a twelve-factor app stores its configuration in an environment that is separate from the application code. This is because any configuration value update will not lead to the application code being rebuilt. But sometimes, it is not realistically possible to store all configs such as security credentials and much more in that environment. It is also common for some configuration to be stored in a database. Since the configuration could be in many different places, a mechanism for obtaining the configuration is required. Quite a...