Modified version of https://developers.google.com/drive/web/quickstart/quickstart-go app, so it caches access token.

quickstart.go

package main

import (
  "fmt"
  "log"
  "os"
  "net/http"
  "code.google.com/p/google-api-go-client/drive/v2"
  "code.google.com/p/goauth2/oauth"
)

// Settings for authorization.
var config = &oauth.Config{
  ClientId:     "YOUR_CLIENT_ID",
  ClientSecret: "YOUR_CLIENT_SECRET",
  Scope:        "https://www.googleapis.com/auth/drive",
  RedirectURL:  "urn:ietf:wg:oauth:2.0:oob",
  AuthURL:      "https://accounts.google.com/o/oauth2/auth",
  TokenURL:     "https://accounts.google.com/o/oauth2/token",
}

func GetNewToken() (*oauth.Token, *oauth.Transport) {
  // Generate a URL to visit for authorization.
  authUrl := config.AuthCodeURL("state")
  log.Printf("Go to the following link in your browser: %v\n", authUrl)
  // Read the code, and exchange it for a token.
  log.Printf("Enter verification code: ")
  var code string
  fmt.Scanln(&code)

  t := &oauth.Transport{
    Config:    config,
    Transport: http.DefaultTransport,
  }
  token, err := t.Exchange(code)
  if err != nil {
    log.Fatalf("An error occurred exchanging the code: %v\n", err)
  }
  return token, t
}

// Uploads a file to Google Drive
func main() {
  var cache oauth.Cache = oauth.CacheFile("access_token.json")
  token, err := cache.Token()
  var t *oauth.Transport
  if err != nil {
    log.Printf("Need a new token. Cannot load old one.")
    token, t = GetNewToken()
    cache.PutToken(token)
  } else {
    t = &oauth.Transport{
      Config:    config,
      Token:     token,
      Transport: http.DefaultTransport,
    }
  }

  // Create a new authorized Drive client.
  svc, err := drive.New(t.Client())
  if err != nil {
    log.Fatalf("An error occurred creating Drive client: %v\n", err)
  }

  // Define the metadata for the file we are going to create.
  f := &drive.File{
    Title: "My Document",
    Description: "My test document",
  }

  // Read the file data that we are going to upload.
  m, err := os.Open("document.txt")
  if err != nil {
    log.Fatalf("An error occurred reading the document: %v\n", err)
  }

  // Make the API request to upload metadata and file data.
  r, err := svc.Files.Insert(f).Media(m).Do()
  if err != nil {
    log.Fatalf("An error occurred uploading the document: %v\n", err)
  }
  log.Printf("Created: ID=%v, Title=%v\n", r.Id, r.Title)
}