json.Marshal如何http.newRequest的正文

I'm working to create a little console for manage digitalocean droplets, this is my first experience with Go..

I have this error

cannot use s (type []byte) as type io.Reader in argument to http.NewRequest:
[]byte does not implement io.Reader (missing Read method)

How can i convert s []bytes in a good type of value for func NewRequest?! NewRequest expect Body of type io.Reader..

s, _ := json.Marshal(r);

// convert type

req, _ := http.NewRequest("GET", "https://api.digitalocean.com/v2/droplets", s)                                          
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))                                                          
req.Header.Set("Content-Type", "application/json")                            
response, _ := client.Do(req)

Thanks!

As @elithrar says use bytes.NewBuffer

b := bytes.NewBuffer(s)
http.NewRequest(..., b) 

That will create a *bytes.Buffer from []bytes. and bytes.Buffer implements the io.Reader interface that http.NewRequest requires.