koanf

koanf (pronounced conf; a play on the Japanese Koan) is a library for reading configurations from different sources in different formats in Go applications. 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. Any delimiter can be chosen. Configuration from multiple sources can be loaded and merged into a koanf instance, for example, load from a file first and override certain values with flags from the command line.