Vitess v17 introduced viper, a library to provide unified configuration management, to the project.

It acts as a registry for configuration values coming from a variety of sources, including:

• Default values.
• Configuration files (JSON, YAML, TOML, and other formats supported), including optionally watching and live-reloading.
• Environment variables.
• Command-line flags, primarily from pflag.Flag types.

It is used by a wide variety of Go projects, including hugo and kops.