auth server

auth.go

package main

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

// All requests will go here first to see if client is authenticated
func authHandler(w http.ResponseWriter, r *http.Request) {
	authToken := r.Header.Get("X-Auth-Token")

	// no auth token - respond unathorized
	if authToken == "" {
		log.Println("unathorized access")
		w.WriteHeader(401)
		return
	}

	// hardcoded example - simulate fetching from auth storage
	if authToken != "abc123" {
		log.Println("invalid auth token, unathorized")
		w.WriteHeader(401)
		return
	}

	// client is authenticated - set header to pass downstream
	// to let services know where the request originated from
	log.Println("adding client header")
	w.Header().Set("X-Client-ID", "acmecorp")
	w.WriteHeader(200)
}

// only authorized access will hit this endpoint
func helloHandler(w http.ResponseWriter, r *http.Request) {
	client := r.Header.Get("X-Client-ID")
	fmt.Fprintln(w, "you're authenticated "+client)
}

func main() {
	addr := "0.0.0.0:5000"

	router := http.NewServeMux()
	router.HandleFunc("/", helloHandler)
	router.HandleFunc("/auth", authHandler)

	srv := &http.Server{
		Addr:         addr,
		WriteTimeout: time.Second * 5,
		ReadTimeout:  time.Second * 5,
		Handler:      router,
	}
	log.Fatal(srv.ListenAndServe())
}