go.uber.org/zap logging with timestamp

hello.go

package main

import (
	"encoding/json"

	"go.uber.org/zap"
)

func main() {
	logFilePath := "/tmp/hello.log"
	rawJSON := []byte(`{
	  "level": "debug",
	  "encoding": "json",
	  "outputPaths": ["stdout", "` + logFilePath + `"],
	  "errorOutputPaths": ["stderr", "` + logFilePath + `"],
	  "encoderConfig": {
	    "messageKey": "message",
	    "levelKey": "level",
	    "levelEncoder": "lowercase",
	    "timeKey": "ts",
	    "timeEncoder": "ISO8601"        
	  }
	}`)

	var cfg zap.Config
	if err := json.Unmarshal(rawJSON, &cfg); err != nil {
		panic(err)
	}
	logger, err := cfg.Build()
	if err != nil {
		panic(err)
	}
	defer logger.Sync()

	logger.Info("Hello World")
	//{"level":"info","ts":"2018-10-23T16:34:07.301-0700","message":"Hello World"}
}