key_reader.go

package string_utils

import (
	"os"
	"strings"
)

//KeyReader is an interface to read string "<key>":"<value>" pairs
//which is common to read from the environment
//it is abstracted so the same interface can be implemented for
//reading for example from REDIS and other sources
type KeyReader interface {
	Keys(prefix string) []string
	GetString(key string) (value string, ok bool)
}

func EnvironmentKeyReader() KeyReader {
	return envKeyReader{}
}

type envKeyReader struct{}

func (envKeyReader) GetString(key string) (value string, ok bool) {
	value = os.Getenv(key)
	if value == "" {
		return "", false
	}
	return value, true
}

func (envKeyReader) Keys(prefix string) []string {
	keys := []string{}
	for _, env := range os.Environ() {
		if strings.HasPrefix(env, prefix) {
			keys = append(keys, strings.SplitN(env, "=", 2)[0])
		}
	}
	return keys
}