zerolog是一个高性能，支持日志等级，钩子的结构化日志库。log的Print()和Printf()方法默认输出到os.Stderr，默认日志等级为debug，用法和官方log库相同。
package main
import (
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
func main(){
zerolog.TimeFieldFormat = zerolog.TimeFormatUnix
log.Print("hello world")
}
{"level":"debug","time":1576398679,"message":"hello world"}
日志等级
zerolog有下面几种日志等级，调用zerolog.SetGlobalLevel()设置日志等级。
- panic (zerolog.PanicLevel, 5)
- fatal (zerolog.FatalLevel, 4)
- error (zerolog.ErrorLevel, 3)
- warn (zerolog.WarnLevel, 2)
- info (zerolog.InfoLevel, 1)
- debug (zerolog.DebugLevel, 0)
- trace (zerolog.TraceLevel, -1)
添加数据到上下文
zerolog可以将数据以key-value对的形式添加到一条日志事件的上下文中，重复的key-value对不会删除。调用Msg方法输出日志，也可以调用Send方法输出日志，其本质是调用Msg("")。
package main
import (
"github.com/rs/zerolog/log"
)
func main(){
log.Debug().
Str("name", "xy").
Str("name", "xy").
Float64("height", 100.0).
Msg("create object")
}
{"level":"debug","name":"xy","name":"xy","height":100,"time":"2019-12-15T17:17:46+08:00","message":"create object"}
自定义字段名
package main
import (
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
func main(){
zerolog.TimestampFieldName = "t"
zerolog.LevelFieldName = "l"
zerolog.MessageFieldName = "m"
log.Debug().
Str("name", "xy").
Float64("height", 100.0).
Msg("create object")
}
{"l":"debug","name":"xy","height":100,"t":"2019-12-15T17:04:24+08:00","m":"create object"}
添加文件名和代码行
package main
import (
"github.com/rs/zerolog/log"
)
func main(){
log.Logger = log.With().Caller().Logger()
log.Info().Msg("hello world")
}
{"level":"info","time":"2019-12-15T17:13:02+08:00","caller":"C:/Users/Administrator/go/src/studygo/main.go:10","message":"hello world"}
logger
zerolog可以创建不同的logger实例来输出日志，下面代码创建了一个新的logger替换了log的logger，其中zerolog.ConsoleWriter可以使输出的日志更加友好，日志等级变为彩色的。
package main
import (
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
"os"
)
func main(){
log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr,TimeFormat: "2006-01-02 15:04:05.000"})
log.Info().Msg("hello world")
}
钩子
利用钩子可以拦截日志事件，从而实现各种扩展功能，例如将日志输出到文件。
package main
import (
"fmt"
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
type LogHook struct{}
func (hook LogHook) Run(e *zerolog.Event, level zerolog.Level, msg string) {
fmt.Println(msg)
}
func main(){
log.Logger=log.Hook(LogHook{})
log.Info().Msg("hello world")
}
hello world
{"level":"info","time":"2019-12-15T17:28:58+08:00","message":"hello world"}
