Golang请求日志收集实现详解

func LoggingMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        start := time.Now()

        // 记录客户端IP
        clientIP := r.RemoteAddr
        if ip := r.Header.Get("X-Real-IP"); ip != "" {
            clientIP = ip
        } else if ip = r.Header.Get("X-Forwarded-For"); ip != "" {
            clientIP = strings.Split(ip, ",")[0]
        }

        // 包装ResponseWriter以捕获状态码
        rw := &responseWriter{ResponseWriter: w, statusCode: http.StatusOK}

        // 调用下一个处理器
        next.ServeHTTP(rw, r)

        // 日志输出
        log.Printf(
            "%s %s %s %d %v",
            r.Method,
            r.URL.Path,
            clientIP,
            rw.statusCode,
            time.Since(start),
        )
    })
}

type responseWriter struct {
    http.ResponseWriter
    statusCode int
}

func (rw *responseWriter) WriteHeader(code int) {
    rw.statusCode = code
    rw.ResponseWriter.WriteHeader(code)
}

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprintf(w, "Hello, World!")
    })

    // 使用中间件包裹处理器
    loggedMux := LoggingMiddleware(mux)

    log.Println("Server starting on :8080")
    http.ListenAndServe(":8080", loggedMux)
}

GET / 127.0.0.1:54321 200 123.456µs

logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
logger.Info("request",
    "method", r.Method,
    "path", r.URL.Path,
    "ip", clientIP,
    "status", rw.statusCode,
    "duration_ms", time.Since(start).Milliseconds(),
)