Parse yaml with dynamic key name usign go.

main.go

package main

import (
	"io/ioutil"
	"log"

	"gopkg.in/yaml.v2"
)

type Config struct {
	Key string `yaml:"key"`
}

func main() {
	b, err := ioutil.ReadFile("./settings.yml")
	if err != nil {
		log.Fatal(err)
	}

	var cfg map[string]Config
	if err := yaml.Unmarshal(b, &cfg); err != nil {
		log.Fatal(err)
	}

	log.Printf("%+v", cfg)
}

settings.yml

development:
    key: arg_for_development

production:
    key: arg_for_production

env1:
    key: arg_for_env1