Read body twice. http://stackoverflow.com/questions/31884093/read-multiple-time-a-reader

payload.json

{
	"Name": "Elvis",
	"Location": "Memphis"
}

readtwice.go

// Run in one window:
//
//     $ go run readtwice.go
//
// An in another:
//
//     $ curl -d @payload.json localhost:8080/
//
// You should see something like:
//
// 2015/08/07 20:57:01 entering readFirst
// 2015/08/07 20:57:01 deserialized payload from body: {Elvis Memphis}
// 2015/08/07 20:57:01 entering readSecond
// 2015/08/07 20:57:01 request body: {	"Name": "Elvis",	"Location": "Memphis"}
//
package main

import (
	"bytes"
	"encoding/json"
	"io"
	"io/ioutil"
	"log"
	"net/http"
)

type Payload struct {
	Name     string
	Location string
}

func readSecond(w http.ResponseWriter, r *http.Request) {
	log.Println("entering readSecond")

	// r.Body is a io.ReadCloser, that's all we know
	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		log.Fatal(err)
	}

	// closing a NopCloser won't hurt anybody
	defer r.Body.Close()

	log.Printf("request body: %s", string(b))
}

func readFirst(w http.ResponseWriter, r *http.Request) {
	log.Println("entering readFirst")

	// temporary buffer
	b := bytes.NewBuffer(make([]byte, 0))

	// TeeReader returns a Reader that writes to b what it reads from r.Body.
	reader := io.TeeReader(r.Body, b)

	// some business logic
	var payload Payload
	if err := json.NewDecoder(reader).Decode(&payload); err != nil {
		log.Fatal(err)
	}

	// we are done with body
	defer r.Body.Close()

	log.Printf("deserialized payload from body: %v", payload)

	// NopCloser returns a ReadCloser with a no-op Close method wrapping the provided Reader r.
	r.Body = ioutil.NopCloser(b)
}

func handler(w http.ResponseWriter, r *http.Request) {
	readFirst(w, r)
	readSecond(w, r)
}

func main() {
	http.HandleFunc("/", handler)
	log.Fatal(http.ListenAndServe(":8080", nil))
}