Golang Middleware Example

middleware-example.go

package main

import (
	"fmt"
	"net/http"
	"net/url"
	"os"

	"github.com/gorilla/context"
	"github.com/gorilla/handlers"
	"github.com/gorilla/mux"
)

type wrapperMiddleware struct {
	h http.Handler
}

func (h wrapperMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	xCraft := r.Header.Values("X-CRAFT")
	if len(xCraft) == 0 {
		return
	}

	contextReq := http.Request{}
	contextReq.URL, _ = url.Parse(xCraft[0])

	context.Set(r, "contextReq", &contextReq)

	h.h.ServeHTTP(w, r)
}

func newWrapperMiddleware(h http.Handler) http.Handler {
	return wrapperMiddleware{h}
}

type authenticatedMiddleware struct {
	h http.Handler
}

func (h authenticatedMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	contextReq := context.Get(r, "contextReq").(*http.Request)
	client := &http.Client{}
	fmt.Println(contextReq)
	resp, err := client.Do(contextReq)
	if err !=  nil {
		w.WriteHeader(404)
		return
	}
	fmt.Println(resp.StatusCode)

	h.h.ServeHTTP(w, r)
}

func newAuthenticatedMiddleware(h http.Handler) http.Handler {
	return authenticatedMiddleware{h}
}

func simpleRequestHandler(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("Hello World!\n"))
}

func authenticatedEndpoint(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("Hello Authenticated User!\n"))
}

func main() {
	r := mux.NewRouter()
	r.Handle("/", newAuthenticatedMiddleware(http.HandlerFunc(authenticatedEndpoint)))

	r.Use(func(handler http.Handler) http.Handler {
		return handlers.LoggingHandler(os.Stdout, handler)
	})
	r.Use(handlers.CompressHandler)
	r.Use(handlers.RecoveryHandler())
	r.Use(newWrapperMiddleware)

	http.ListenAndServe(":8080", r)
}