Why Viper?

When building a modern application, you don’t want to worry aboutconfiguration file formats; you want to focus on building awesome software.Viper is here to help with that.

Viper does the following for you:

• Find, load, and unmarshal a configuration file in JSON, TOML, YAML, HCL, or Java properties formats.
• Provide a mechanism to set default values for your differentconfiguration options.
• Provide a mechanism to set override values for options specified throughcommand line flags.
• Provide an alias system to easily rename parameters without breaking existingcode.

• Make it easy to tell the difference between when a user has provided acommand line or config file which is the same as the default.
  Viper uses the following precedence order. Each item takes precedence over theitem below it:

• explicit call to Set

• flag
• env
• config
• key/value store
• default
  Viper configuration keys are case insensitive.