First MUX, then middlewares

middlewares_after_mux.go

package main

import (
	"log"
	"net/http"
)

func main() {
	if err := rightWay(); err != nil {
		panic(err)
	}
}

func wrongWay() error {
	middleware1 := func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
			log.Printf("middleware 1: %s", request.PathValue("user"))

			next.ServeHTTP(writer, request)
		})
	}
	middleware2 := func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
			log.Printf("middleware 2: %s", request.PathValue("user"))

			next.ServeHTTP(writer, request)
		})
	}

	mux := http.NewServeMux()

	mux.Handle("/hello/{user}", http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
		writer.Write([]byte("Hello, " + request.PathValue("user")))
	}))

	return http.ListenAndServe(":8080", middleware1(middleware2(mux)))
}

func rightWay() error {
	middleware1 := func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
			log.Printf("middleware 1: %s", request.PathValue("user"))

			next.ServeHTTP(writer, request)
		})
	}
	middleware2 := func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(writer http.ResponseWriter, request *http.Request) {
			log.Printf("middleware 2: %s", request.PathValue("user"))

			next.ServeHTTP(writer, request)
		})
	}

	buildHandlerWithMiddlewares := func(fn func(writer http.ResponseWriter, request *http.Request)) http.Handler {
		return middleware1(middleware2(http.HandlerFunc(fn)))
	}

	mux := http.NewServeMux()

	mux.Handle("/hello/{user}", buildHandlerWithMiddlewares(func(writer http.ResponseWriter, request *http.Request) {
		writer.Write([]byte("Hello, " + request.PathValue("user")))
	}))

	return http.ListenAndServe(":8080", mux)
}

Test with

curl localhost:8080/hello/utku