golang[60]-viper

简单的说，viper就是 go 语言中高效解决配置信息的: https://github.com/spf13/viper

What is Viper?

Viper is a complete configuration solution for Go applications including 12-Factor apps. It is designed to work within an application, and can handle all types of configuration needs and formats. It supports:

• setting defaults
• reading from JSON, TOML, YAML, HCL, and Java properties config files
• live watching and re-reading of config files (optional)
• reading from environment variables
• reading from remote config systems (etcd or Consul), and watching changes
• reading from command line flags
• reading from buffer
• setting explicit values
• Viper can be thought of as a registry for all of your applications configuration needs.

Why Viper?

When building a modern application, you don’t want to worry about configuration file formats; you want to focus on building awesome software. Viper is here to help with that.

Viper does the following for you:

Find, load, and unmarshal a configuration file in JSON, TOML, YAML, HCL, or Java properties formats.

Provide a mechanism to set default values for your different configuration options.

Provide a mechanism to set override values for options specified through command line flags.

Provide an alias system to easily rename parameters without breaking existing code.

Make it easy to tell the difference between when a user has provided a command line or config file which is the same as the default.

Viper uses the following precedence order. Each item takes precedence over the item below it:

explicit call to Set

• flag
• env
• config
• key/value store
• default
• Viper configuration keys are case insensitive.

用例1:读取环境变量信息

绑定变量名为id，前缀spf。则环境变量中设置时必须为SPF_ID

viper.SetEnvPrefix("spf") // 前缀、will be uppercased automatically
viper.BindEnv("id")

os.Setenv("SPF_ID", "13") // typically done outside of the app  export SPF_ID=3000

id := viper.Get("id") // 13
fmt.Println(id)

自动绑定：

 viper.SetEnvPrefix(`spf`)
viper.AutomaticEnv()

id := viper.Get("id")

fmt.Println(id)

用例2:读取配置文件信息

{
  "debug": true,
  "server": {
    "address": ":9090"
  },
  "context":{
    "timeout":2
  },
  "database": {
      "host": "mysql",
      "port": "3306",
      "user": "user",
      "pass": "password",
      "name": "article"
  }

}

package main

import (
	"fmt"
	"github.com/spf13/viper"
)

func main(){

	viper.SetConfigFile(`config.json`)
	err := viper.ReadInConfig()

	if err != nil {
		panic(err)
	}

	if viper.GetBool(`debug`) {
		fmt.Println("Service RUN on DEBUG mode")
	}

	dbHost := viper.GetString(`database.host`)
	dbPort := viper.GetString(`database.port`)
	dbUser := viper.GetString(`database.user`)
	dbPass := viper.GetString(`database.pass`)
	dbName := viper.GetString(`database.name`)
	connection := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s", dbUser, dbPass, dbHost, dbPort, dbName)

	fmt.Println(connection)
}

用例3:命令行参数：

package main


import (
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
	"fmt"
)

func main(){

	pflag.Int("flagname", 1234, "help message for flagname")

	pflag.Parse()
	viper.BindPFlags(pflag.CommandLine)

	i := viper.GetInt("flagname") // retrieve values from viper instead of pflag
	fmt.Println(i)
}