Stært

Stært is a Go library for loading and merging a program configuration structure from many sources.

Overview

Stært was born in order to merge two sources of Configuration (Flæg, Toml). We developed flaeg and staert in order to simplify configuration maintenance on traefik.

Features

Load your Configuration structure from many sources
Keep your Configuration structure values unchanged if no overwriting (support defaults values)
Two native sources :
- Flæg
- Toml
An Interface to add your own sources
Handle pointers field :
- You can give a structure of default values for pointers
- Same comportment as Flæg
Stært is Command oriented
- It use flaeg.Command
- Same comportment as Flæg commands

Getting Started

The configuration

It works on your own Configuration structure, like this one :

package example

import (
	"fmt"
	"github.com/containous/flaeg"
	"github.com/containous/staert"
	"os"
)

//Configuration is a struct which contains all differents type to field
type Configuration struct {
	IntField     int                      `description:"An integer field"`
	StringField  string                   `description:"A string field"`
	PointerField *PointerSubConfiguration `description:"A pointer field"`
}

//PointerSubConfiguration is a SubStructure Configuration
type PointerSubConfiguration struct {
	BoolField  bool    `description:"A boolean field"`
	FloatField float64 `description:"A float field"`
}

Let's initialize it:

 func main() {
	//Init with default value
	config := &Configuration{
		IntField:    1,
		StringField: "init",
		PointerField: &PointerSubConfiguration{
			FloatField: 1.1,
		},
	}
	//Set default pointers value
	defaultPointersConfig := &Configuration{
		PointerField: &PointerSubConfiguration{
			BoolField:  true,
			FloatField: 99.99,
		},
	}

The command

Stært uses flaeg.Command Structure, like this :

    //Create Command
    command:=&flaeg.Command{
        Name:"example",
        Description:"This is an example of description",
        Config:config,
        DefaultPointersConfig:defaultPointersConfig,
        Run: func() error {
            fmt.Printf("Run example with the config :\n%+v\n",config)
 			fmt.Printf("PointerField contains:%+v\n", config.PointerField)
            return nil
        }
    }

Use stært with sources

Init Stært

    s:=staert.NewStaert(command)

Init TOML source

     toml:=staert.NewTomlSource("example", []string{"./toml/", "/any/other/path"})

Init Flæg source

     f:=flaeg.New(command, os.Args[1:])

Add sources

Add TOML and flæg sources

    s.AddSource(toml)
    s.AddSource(f)

NB : You can change order, so that, flaeg configuration will overwrite toml one

Load your configuration

Just call LoadConfig function :

	loadedConfig, err := s.LoadConfig();
    if err != nil {
		//OOPS
	}
	//DO WATH YOU WANT WITH loadedConfig 
	//OR CALL RUN FUNC

You can call Run

Run function will call the func run() from the command :

    if err := s.Run(); err != nil {
		//OOPS
	}
 }

NB : If you didn't call LoadConfig() before, your func run() will use your original configuration

Let's run example

TOML file ./toml/example.toml :

IntField= 2
[PointerField]

We can run the example program using folowing CLI arguments :

$ ./example --stringfield=owerwrittenFromFlag --pointerfield.floatfield=55.55
Run example with the config :
&{IntField:2 StringField:owerwrittenFromFlag PointerField:0xc82000ec80}
PointerField contains:&{BoolField:true FloatField:55.55}

Contributing

Fork it!
Create your feature branch: git checkout -b my-new-feature
Commit your changes: git commit -am 'Add some feature'
Push to the branch: git push origin my-new-feature
Submit a pull request :D

davidbirdsong/staert