Cloud-Native Applications in Java

Externalizing configuration

Configuration can be any property that is likely to differ between environments or production deployments. Typical examples are queue and topic names, ports, URLs, connection and pool properties, and so on.

A deployable should not have configuration in it. A configuration should be injected from outside. This makes the deployable unit immutable as it goes through the various stages of the life cycle, such as Dev, QA, and UAT.

Let's assume we have to run our product service in different environments, where the URL differentiates the environment. Therefore, the small change we make in the request mapping is as follows:

@RequestMapping("/${env}product/{id}")Product getProduct(@PathVariable("id") int id) {

We can inject ...