Exchanges a Google Oauth2 refresh token for a bearer token

gbear.go

package main

import (
	"bytes"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
)

func main() {
	data := url.Values{}
	data.Set("refresh_token", os.Args[1])
	data.Set("grant_type", "refresh_token")
	data.Set("client_id", os.Getenv("GOOGLE_CLIENT_ID"))
	data.Set("client_secret", os.Getenv("GOOGLE_CLIENT_SECRET"))

	req, err := http.NewRequest("POST", "https://www.googleapis.com/oauth2/v4/token", bytes.NewBufferString(data.Encode()))
	if err != nil {
		panic(err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer resp.Body.Close()

	io.Copy(os.Stdout, resp.Body)
}