Go oauth2 sample for Github

go-oauth2.go

package main

import (
	"context"
	"fmt"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/endpoints"
	"log"
	"net"
	"net/http"
	"os/exec"
	"runtime"
)

func main() {
	codeCh, err := startWebServer()
	if err != nil {
		log.Fatal("Unable to start a web server.detail:", err.Error())
	}

	ctx := context.Background()
	// Set ClientId and ClientSecret to
	oauthConf := &oauth2.Config{
		ClientID:     "cfe0990674f9fe389fd2",
		ClientSecret: "78b7a026ab42716b0e1afa3b4fbc64bbc2040c6f",
		// select level of access you want https://developer.github.com/v3/oauth/#scopes
		Scopes:   []string{"user:email", "repo"},
		Endpoint: endpoints.GitHub,
	}

	// Redirect user to consent page to ask for permission
	// for the scopes specified above.
	authURL := oauthConf.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
	err = openURL(authURL)

	if err != nil {
		log.Fatalf("Unable to open authorization URL in web server: %v", err)
	} else {
		fmt.Println("Your browser has been opened to an authorization URL.",
			" This program will resume once authorization has been provided.")
		fmt.Println(authURL)
	}

	// Wait for the web server to get the code.
	code := <-codeCh

	tok, err := oauthConf.Exchange(ctx, code)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Token:", tok.AccessToken)
}

// startWebServer starts a web server that listens on http://localhost:8080.
// The webserver waits for an oauth code in the three-legged auth flow.
func startWebServer() (codeCh chan string, err error) {
	listener, err := net.Listen("tcp", "localhost:8080")
	if err != nil {
		return nil, err
	}
	codeCh = make(chan string)

	go http.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		code := r.FormValue("code")
		codeCh <- code // send code to OAuth flow
		_ = listener.Close()
		w.Header().Set("Content-Type", "text/plain")
		_, _ = fmt.Fprintf(w, "Received code: %v\r\nYou can now safely close this browser window.", code)
	}))

	return codeCh, nil
}

func openURL(url string) error {
	var err error
	switch runtime.GOOS {
	case "linux":
		err = exec.Command("xdg-open", url).Start()
	case "windows":
		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", "http://localhost:4001/").Start()
	case "darwin":
		err = exec.Command("open", url).Start()
	default:
		err = fmt.Errorf("cannot open URL %s on this platform", url)
	}
	return err
}