koanf

koanf is a library for reading configuration from different sources in different formats in Go applications. It is a cleaner, lighter alternative to spf13/viper with better abstractions and extensibility and far fewer dependencies. koanf v2 has modules (Providers) for reading configuration from a variety of sources such as files, command line flags, environment variables, Vault, and S3 and for parsing (Parsers) formats such as JSON, YAML, TOML, Hashicorp HCL.