koanf
Simple, lightweight, extensible, configuration management library
...It is a cleaner, lighter alternative to spf13/viper with better abstractions and extensibility, and fewer dependencies. koanf comes with built-in support for reading configuration from files, command line flags, and environment variables, and can parse JSON, YAML, TOML, and Hashicorp HCL. Any external dependencies are detached from the core into sub-packages, so only the ones that are explicitly referenced get compiled into an application. Once loaded into koanf, configuration are values queried by a delimited key path syntax. eg: app.server.port. ...