Go Standard Library Cookbook

How to do it...

1. Open the console and create the folder chapter09/recipe06.
2. Navigate to the directory.
3. Create the middleware.go file with the following content:

        package main        import (          "io"          "net/http"        )        func main() {          // Secured API          mux := http.NewServeMux()          mux.HandleFunc("/api/users", Secure(func(w http.ResponseWriter,                         r *http.Request) {            io.WriteString(w,  `[{"id":"1","login":"ffghi"},                           {"id":"2","login":"ffghj"}]`)          }))          http.ListenAndServe(":8080", mux)        }        func Secure(h http.HandlerFunc) http.HandlerFunc {          return func(w http.ResponseWriter, r *http.Request) {            sec := r.Header.Get("X-Auth")            if sec != "authenticated" {              w.WriteHeader(http.StatusUnauthorized)              return            }            h(w, r) // use the handler          }        }

4. Execute the code by go run middleware.go.
5. Check ...