go get -u github.com/derekparker/delve/cmd/dlv

func main(){
 http.HandleFunc("/test",func(writer http.ResponseWriter,req *http.Request){
 //TODO
 })
 log.Fatal(http.ListenAndServe("127.0.0.1:8080",nil))
}

dlv debug test.go

package mylog
import (
    "log"
    "os"
)
var (
    Debug *log.Logger
    Info *log.Logger
    Error *log.Logger
)
func init() {
    log.Println("init ...")
    Debug = log.New(os.Stdout, "[DEBUG] ", log.Ldate|log.Ltime|log.Lshortfile)
    Info = log.New(os.Stdout, "[INFO] ", log.Ldate|log.Ltime|log.Lshortfile)
    Error = log.New(os.Stderr, "[ERROR] ", log.Ldate|log.Ltime|log.Lshortfile)
}
package main
import "mylog"
func main(){
  mylog.Debug.Println("good");
  mylog.Info.Println("good");
  mylog.Error.Println("good");
}