go viper包

什么是viper

viper大神spf13编写的开源配置解决方案，viper拥有以下功能以及特性：

1、设置默认值

2、从json、toml yaml、hci和java属性配置文件

3、从环境变量env读取值

4、远程读取配置文件

5、key不区分大小写

举例说明：

1、配置文件如下：

statetransfer:

    # Should a replica attempt to fix damaged blocks?

    # In general, this should be set to true, setting to false will cause

    # the replica to panic, and require a human's intervention to intervene

    # and fix the corruption

    recoverdamage: true

    # The number of blocks to retrieve per sync request

    blocksperrequest: 20    # The maximum number of state deltas to attempt to retrieve

    # If more than this number of deltas is required to play the state up to date

    # then instead the state will be flagged as invalid, and a full copy of the state

    # will be retrieved instead

    maxdeltas: 200    # Timeouts

    timeout:

        # How long may returning a single block take

        singleblock: 2s

        # How long may returning a single state delta take

        singlestatedelta: 2s

        # How long may transferring the complete state take

        fullstate: 60s

peer:

    abcd:  3322d

代码如下：

viper.SetConfigName(cmdRoot)

viper.AddConfigPath("./")

err := viper.ReadInConfig()

if err != nil {

fmt.Println(fmt.Errorf("Fatal error when reading %s config file: %s\n", cmdRoot, err))

}

environment := viper.GetBool("security.enabled")

fmt.Println("environment:", environment)

fullstate := viper.GetString("statetransfer.timeout.fullstate")

fmt.Println("fullstate:", fullstate)

abcValue := viper.GetString("peer.abcd")

fmt.Println("abcdValuea is :", abcValue)

上面介绍了以下viper的简单功能，下面写个稍微复杂的实例。

1、首先，定义个配置文件对应的结构体：

type Configstruct {

        PostgreSQL struct {

            DSNstring `mapstructure:"dsn"`

            Automigrate bool

            DB    string

       }    `mapstructure:"postgresql"`

      Redis struct {

            URLstring `mapstructure:"url"`

            Pool *redis.Pool

      }

}

2、利用viper的SetDefault方法设置变量

viper.SetDefault("postgresql.dsn", "postgres://localhost/loraserver_as?sslmode=disable")

viper.SetDefault("postgresql.automigrate", true)

viper.SetDefault("redis.url", "redis://localhost:6379")

3、解析viper数据到上述结构体中

var config Config

viper.Unmarshal(&config)

这样，就可以将步骤2中设置的默认配置映射到Config结构体对应的变量中了。

具体流程，首先viper的SetDefault方法，用“.”作为分隔符key，然后将其存储到map[string]interface{}结构内。下面在做viper.Unmarshal(&config)时，根据Config结构体中定义的mapstructure的tag值进行解析（其中mapstructure是个第三方包）。