Add the configure ercole using TOML instead of JSON

[amreo]

Is your feature request related to a problem? Please describe.
The JSON format doesn't support comments so I want to configure ercole with TOML instead of JSON.

Describe the solution you'd like
I want that when ercole starts, it (also) reads the configuration files written in TOML

[amreo]

I tried to modify the function readConfig for adding the support to this feature but the onion and mergo are buggy, don't fit well and are incomplete...

func readConfig() config.Configuration {
	var conf config.Configuration

	layers := make([]onion.Layer, 0)
	l1, err := onion.NewFileLayer("/opt/ercole/config.json", nil)
	if err == nil {
		layers = append(layers, l1)
	}
	l2, err := onion.NewFileLayer("/usr/share/ercole/config.json", nil)
	if err == nil {
		layers = append(layers, l2)
	}
	l3, err := onion.NewFileLayer("/etc/ercole.json", nil)
	if err == nil {
		layers = append(layers, l3)
	}
	home, _ := os.UserHomeDir()
	l4, err := onion.NewFileLayer(home+"/.ercole.json", nil)
	if err == nil {
		layers = append(layers, l4)
	}
	l5, err := onion.NewFileLayer("config.json", nil)
	if err == nil {
		layers = append(layers, l5)
	}
	l6, err := onion.NewFileLayer(extraConfigFile, nil)
	if err == nil {
		layers = append(layers, l6)
	}
	l7 := onion.NewEnvLayerPrefix("_", "ERCOLE")
	layers = append(layers, l7)
	o := onion.New(layers...)

	//Onion doesn't support a getall like function, so I use this trick to decode all fields to the struct
	v := reflect.ValueOf(&conf).Elem()
	t := v.Type()
	for i := 0; i < t.NumField(); i++ {
		val, ok := o.Get(t.Field(i).Name)
		if ok {
			fmt.Println("q_ui10")
			err := mergo.Map(v.Field(i).Addr().Interface(), val, mergo.WithOverride, mergo.WithTransformers(utils.Float64toIntTransfomer{}))
			if err != nil {
				fmt.Printf("%s %T\n", v.Field(i).Type().String(), val)
				panic(err)

			}
		}
	}

	config.PatchConfiguration(&conf)

	//Return the read configuration
	return conf
}

func (t Float64toIntTransfomer) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
	if typ.Kind() == reflect.Float32 || typ.Kind() == reflect.Float64 || typ.Kind() == reflect.Int {
		return func(dst, src reflect.Value) error {
			if dst.CanSet() {
				if dst.Kind() == reflect.Int {
					dst.SetInt(int64(src.Float()))
				} else {
					dst.Set(src)
				}
			}
			return nil
		}
	}
	return nil
}

See darccio/mergo#138 and goraz/onion#18

[amreo]

I need a configuration library that

• support TOML
• support reading multiple files in the same directory (e.g /etc/sysctl.d) (Add support for reading multiple configuration files in /etc/ercole.d/ #61)
• support merging configuration between the layers
• support configuration file with different names

[cirelli94]

Hi @amreo,
https://github.com/goraz/onion that you already tried:

• support TOML
• support merging configuration between the layers

It doesn't support multiple files in the same directory, but we can merge the files easily, thanks to TOML format.

What do you mean with your last point? "Support configuration file with different names"?

[amreo]

support merging configuration between the layers

Are you sure that it support merging configuration between the layers??????

What do you mean with your last point? "Support configuration file with different names"?

I mean that different file in different directory can have different names, for example ~/.ercole.json, /etc/ercole.json, config.json

Cobra, for example, doesn't suppor this feature. See
SetConfigName and AddConfigPath