HTTP request logger in Go

log.go

package __package__

import (
	"net/http"
	"time"
)

type responseLogger struct {
	w      http.ResponseWriter
	status int
	size   int
}

func (r *responseLogger) Header() http.Header {
	return r.w.Header()
}

func (r *responseLogger) Write(b []byte) (int, error) {
	if r.status == 0 {
		// Status will be StatusOK if WriteHeader not called yet
		r.status = http.StatusOK
	}
	size, err := r.w.Write(b)
	r.size += size
	return size, err
}

func (r *responseLogger) WriteHeader(s int) {
	r.w.WriteHeader(s)
	r.status = s
}

func (r *responseLogger) Status() int {
	return r.status
}

func (r *responseLogger) Size() int {
	return r.size
}

// LogRequest logs starting and ending messages for HTTP request with duration
func LogRequest(h http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		rw := &responseLogger{w: w}
		raddr := r.Header.Get("X-Forwarded-For")
		if raddr == "" {
			raddr = r.RemoteAddr
		}
		Infof("Started %s %s for %s", r.Method, r.URL.Path, raddr)
		h.ServeHTTP(rw, r)
		Infof("Completed %v %s in %v",
			rw.Status(),
			http.StatusText(rw.Status()),
			time.Since(start))
	})
}

// LogRequestHandler return a LogRequest handler
func LogRequestHandler(f http.HandlerFunc) http.Handler {
	return LogRequest(http.HandlerFunc(f))
}