Exemple #1
0
func (cs computeSource) Token() (*oauth2.Token, error) {
	if !metadata.OnGCE() {
		return nil, errors.New("oauth2/google: can't get a token from the metadata service; not running on GCE")
	}
	acct := cs.account
	if acct == "" {
		acct = "default"
	}
	tokenJSON, err := metadata.Get("instance/service-accounts/" + acct + "/token")
	if err != nil {
		return nil, err
	}
	var res struct {
		AccessToken  string `json:"access_token"`
		ExpiresInSec int    `json:"expires_in"`
		TokenType    string `json:"token_type"`
	}
	err = json.NewDecoder(strings.NewReader(tokenJSON)).Decode(&res)
	if err != nil {
		return nil, fmt.Errorf("oauth2/google: invalid token JSON from metadata: %v", err)
	}
	if res.ExpiresInSec == 0 || res.AccessToken == "" {
		return nil, fmt.Errorf("oauth2/google: incomplete token received from metadata")
	}
	return &oauth2.Token{
		AccessToken: res.AccessToken,
		TokenType:   res.TokenType,
		Expiry:      time.Now().Add(time.Duration(res.ExpiresInSec) * time.Second),
	}, nil
}
Exemple #2
0
// DefaultTokenSource is a token source that uses
// "Application Default Credentials".
//
// It looks for credentials in the following places,
// preferring the first location found:
//
//   1. A JSON file whose path is specified by the
//      GOOGLE_APPLICATION_CREDENTIALS environment variable.
//   2. A JSON file in a location known to the gcloud command-line tool.
//      On Windows, this is %APPDATA%/gcloud/application_default_credentials.json.
//      On other systems, $HOME/.config/gcloud/application_default_credentials.json.
//   3. On Google App Engine it uses the appengine.AccessToken function.
//   4. On Google Compute Engine, it fetches credentials from the metadata server.
//      (In this final case any provided scopes are ignored.)
//
// For more details, see:
// https://developers.google.com/accounts/application-default-credentials
//
func DefaultTokenSource(ctx context.Context, scope ...string) (oauth2.TokenSource, error) {
	// First, try the environment variable.
	const envVar = "GOOGLE_APPLICATION_CREDENTIALS"
	if filename := os.Getenv(envVar); filename != "" {
		ts, err := tokenSourceFromFile(ctx, filename, scope)
		if err != nil {
			return nil, fmt.Errorf("google: error getting credentials using %v environment variable: %v", envVar, err)
		}
		return ts, nil
	}

	// Second, try a well-known file.
	filename := wellKnownFile()
	_, err := os.Stat(filename)
	if err == nil {
		ts, err2 := tokenSourceFromFile(ctx, filename, scope)
		if err2 == nil {
			return ts, nil
		}
		err = err2
	} else if os.IsNotExist(err) {
		err = nil // ignore this error
	}
	if err != nil {
		return nil, fmt.Errorf("google: error getting credentials using well-known file (%v): %v", filename, err)
	}

	// Third, if we're on Google App Engine use those credentials.
	if appengineTokenFunc != nil {
		return AppEngineTokenSource(ctx, scope...), nil
	}

	// Fourth, if we're on Google Compute Engine use the metadata server.
	if metadata.OnGCE() {
		return ComputeTokenSource(""), nil
	}

	// None are found; return helpful error.
	const url = "https://developers.google.com/accounts/application-default-credentials"
	return nil, fmt.Errorf("google: could not find default credentials. See %v for more information.", url)
}