Go HTTP Middleware

package middleware

import (
	"log"
	"net/http"
	"time"
)

// Logger logs method, path, status, and duration.
func Logger(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		start := time.Now()
		rw := &responseWriter{w, http.StatusOK}
		next.ServeHTTP(rw, r)
		log.Printf("%s %s %d %s", r.Method, r.URL.Path, rw.status, time.Since(start))
	})
}

// CORS adds permissive CORS headers.
func CORS(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Access-Control-Allow-Origin", "*")
		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
		if r.Method == http.MethodOptions {
			w.WriteHeader(http.StatusNoContent)
			return
		}
		next.ServeHTTP(w, r)
	})
}

type responseWriter struct {
	http.ResponseWriter
	status int
}

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