jeyjeyemem

You can still strictly adhere to section III if you choose to - by only loading the environment variables, but Externalized Properties allows more than that if needed.

By using ExternalizedProperties instead of direct System.getenv() you get other useful features such as automatic conversions, variable expansion, and processing (e.g. automatic decryption/automatic base64 decode, etc)

Definitely! There's no limit on what configuration formats Externalized Properties can support as you can implement custom `Resolver`s to retrieve from any source and format e.g.

    public class PklResolver implements Resolver {
        public Optional<String> resolve(InvocationContext context, String propertyName) {
            return getFromPklConfig(propertyName);
        }
    }


    // Register custom resolver when building ExternalizedProperties

    ExternalizedProperties externalizedProperties = ExternalizedProperties.builder()
        .resolvers(new PklResolver(...))
        .build();

    AppProperties appProperties = externalizedProperties.initialize(AppProperties.class);

    // Resolves config from PklResolver

    String myConfig = appProperties.myConfig();

Externalized Properties was inspired by the The Twelve Factor Methodology's section III. Config.

The goal of this library is to make it easy for applications to implement configuration best practices by providing easy-to-use APIs as well as providing the flexibility to choose where to store their configurations/properties.

Externalized Properties takes full advantage of Java's Dynamic Proxies.

Why Dynamic Proxies?

* Dependency Injection Friendly

Since Externalized Properties works with interfaces, it makes it easy to integrate with dependency injection (DI) frameworks. it's as simple as building ExternalizedProperties, initializing a dynamic proxy from an interface, and registering the proxy interface to your chosen DI framework.

* Testing Friendly

Another side-effect of being dependency injection friendly is that it also makes it easy to mock/stub out configurations/properties on unit tests. It's as simple as creating a stub implementation of the proxy interface or using mocking frameworks to mock the proxy interface.

Yes, I am the author. I didn't know that, I'll give it a try. Thank you for the tip!