ergagnon/gocmder

Go Cmder is a library to create go cli with Cobra and Viper.

Go CMDER

Go Cmder combine Cobra and Viper to auto generate command-line tool where the user can control configuration in a precedence order: flags > environment variables > configuration files and the defaults defined by the config.

This library was inspired by Sting of the viper article from Carolyn Van Slyck.

Install

go get github.com/ergagnon/gocmder

How to use

Create the config struct with tags

Supported tags:

1. desc: used for the Flag description.
2. default: default value used in Flag and Viper config. Supported value type: string, int, float32, bool
3. required: set a required Flag.
4. hidden: don't create a Flag when hidden is true.

Example:

type AppConfig struct {
    Directory string `desc:"Directory to browse" default:"."`
    Server ServerConfig // support multi-level config          
}

type ServerConfig struct {
    Url string `desc:"Server url" default:"localhost"`
    Port int `desc:"Username" default:"8080"`
}

Create a Go CMDER with the config and options

Call the function

func NewCmder(cfg any, onFinalize OnFinalizeFunc, opts ...CmderOption) (*Cmder, error)

cli, err := gocmder.NewCmder(AppConfig{}, func(cfg any) error {
    // At this step, the config object has been filled
    // with all the values. 
    // You can use it in your application.
    return nil
})

This will auto-generate

Flags:

Usage:
   [flags]

Flags:
      --directory string    Directory to browse (default ".")
  -h, --help                help for this command
      --server-port int     Username (default 8080)
      --server-url string   Server url (default "localhost")

Environment Variable

DIRECTORY
SERVER_PORT
SERVER_URL

Config file (optional)
Configuration will use Viper defaults.

reading from JSON, TOML, YAML, HCL, envfile and Java properties config files

Yaml example:

directory: "my_dir"
server:
  url: "127.0.0.1"
  port: 8080