Solon Framework Uses a Six-Layer Config Model to Simplify Multi-Environment Apps

Solon, a Java application framework, addresses configuration management across dev, staging, and production environments through a layered override system. The base configuration lives in a resources/app.yml file, with environment-specific files such as app-dev.yml or app-pro.yml loaded based on the solon.env variable. Developers can set the active environment via the config file itself, a JVM system property, a startup argument, or a container environment variable, with each method carrying progressively higher priority. For complex applications, Solon supports splitting configuration across multiple files using solon.config.load, with path expressions that dynamically resolve to the active environment. A defined six-layer hierarchy — from static internal files up to cloud config providers like Nacos — determines which value wins when the same key appears in multiple sources.