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go-http-middleware

A middleware library for go standard net/http library.
Designed to introduce middleware for net/http with small code modification.

Features

• no more third-party libraries required.
• core code are easy to learn and understand.
• fully compatible with the net/http library.

Quick Start

package main

import (
	"log"
	"net/http"
	"os"

	"github.com/AlpsMonaco/go-http-middleware/middleware"
)

var logger = log.New(os.Stdout, "", log.LstdFlags)

func HttpHandleHello(w http.ResponseWriter, r *http.Request) {
	logger.Println("Hello")
	w.Write([]byte("Hello"))
}

func HttpHandleWorld(w http.ResponseWriter, r *http.Request) {
	logger.Println("World")
	w.Write([]byte("World"))
}

func LogMiddleware1(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		logger.Println("log middleware 1 in")
		next(w, r)
		logger.Println("log middleware 1 out")
	}
}

func LogMiddleware2(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		logger.Println("log middleware 2 in")
		next(w, r)
		logger.Println("log middleware 2 out")
	}
}

func main() {
	http := middleware.DefaultHTTPBuilder()
	http.With(LogMiddleware1, LogMiddleware2)
	http.HandleFunc("/hello", HttpHandleHello)
	http.HandleFunc("/world", HttpHandleWorld)
	http.ListenAndServe(":33333", nil)
}

Write your own middleware and add the following two lines of code before registering the HTTP handler in your code.

http := middleware.DefaultHTTPBuilder()
http.With(LogMiddleware1, LogMiddleware2)

No further modifications are needed.

Test

curl http://127.0.0.1:33333/hello

the console will output

2024/02/02 14:00:54 log middleware 1 in
2024/02/02 14:00:54 log middleware 2 in
2024/02/02 14:00:54 Hello
2024/02/02 14:00:54 log middleware 2 out
2024/02/02 14:00:54 log middleware 1 out

Middleware Practice

Logger Middleware

log client addr and request path.

func LogMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		fmt.Printf("%s %s\n", r.RemoteAddr, r.RequestURI)
		next(w, r)
	}
}

Timer Middleware

func TimerMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		st := time.Now()
		next(w, r)
		fmt.Printf("time elapsed:%d\nms",time.Now().Sub(st).Milliseconds())
	}
}

Recovery Middleware

recover if panic

func RecoverMiddleware(next http.HandlerFunc) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		defer func() {
			err := recover()
			if err != nil {
				w.WriteHeader(500)
				fmt.Println(err)
			}
		}()
		next(w, r)
	}
}

Advance

Use middleware.NewBuilder if you use your own mux instead of default mux of net/http.

...
b := middleware.NewBuilder(&http.ServeMux{})
b.With(LogMiddleware1, LogMiddleware2)
b.HandleFunc("/hello", HttpHandleHello)
b.HandleFunc("/world", HttpHandleWorld)
b.ListenAndServe(":33333", nil)