api/internal/config/config.go

package config

import (
	"encoding/json"
	"errors"
	"log"
	"os"
	"sync"
)

var globalMutex sync.Mutex
var global *Config

// Config is configuration
type Config struct {
	Space struct {
		Host      string `json:"host"`
		AccessKey string `json:"accessKey"`
		SecretKey string `json:"secretKey"`
		Bucket    string `json:"bucket"`
		MaxSize   int64  `json:"maxSize"`
		Root      string `json:"root"`
	} `json:"space"`

	Database struct {
		Host      string `json:"host"`
		Port      int    `json:"port"`
		Db        string `json:"db"`
		Username  string `json:"username"`
		Password  string `json:"password"`
		Mechanism string `json:"mechanism"`
	} `json:"database"`

	Wiki struct {
		URL string `json:"url"`
	} `json:"wiki"`
}

// Load loads config stuff
func (config *Config) Load(filename string) error {
	file, err := os.Open(filename)
	if err != nil {
		return err
	}

	return json.NewDecoder(file).Decode(config)
}

// LoadAny loads the first of these files it can find
func (config *Config) LoadAny(filenames ...string) error {
	for _, filename := range filenames {
		if err := config.Load(filename); err == nil {
			return nil
		}

		*config = Config{}
	}

	return errors.New("Failed to load configuration files")
}

// Global gets the global configuration, loading it if this is the first caller
func Global() Config {
	globalMutex.Lock()
	if global == nil {
		global = &Config{}
		err := global.LoadAny("/etc/aiterp/rpdata.json", "./config.json")
		if err != nil {
			log.Fatalln(err)
		}
	}
	globalMutex.Unlock()

	return *global
}