Solon Framework Offers Six-Tier Config Loading With In-File Environment Segments

Solon, a Java application framework, provides a multi-environment configuration system built around a single property called solon.env, which determines which environment-specific config file is loaded alongside the base app.yml. Unlike Spring Boot's profiles API, Solon requires no annotations or profile scanning — just a key-value setting that can be defined in the config file, as a JVM argument, a launch argument, or an OS environment variable, with higher-priority sources overriding lower ones. The framework supports a six-tier config loading stack, ranging from bundled YAML files inside the JAR at the lowest tier to remote config centers like Nacos at the highest. A feature called solon.config.load allows developers to declare additional classpath resources with variable substitution and wildcard support, enabling config to be split by concern such as database, cache, or authentication. Solon also supports in-file environment segments within a single app.yml, a pattern that has no direct equivalent in Spring Boot.