// JWTAccessTokenSourceFromJSON uses a Google Developers service account JSON
// key file to read the credentials that authorize and authenticate the
// requests, and returns a TokenSource that does not use any OAuth2 flow but
// instead creates a JWT and sends that as the access token.
// The audience is typically a URL that specifies the scope of the credentials.
//
// Note that this is not a standard OAuth flow, but rather an
// optimization supported by a few Google services.
// Unless you know otherwise, you should use JWTConfigFromJSON instead.
func JWTAccessTokenSourceFromJSON(jsonKey []byte, audience string) (oauth2.TokenSource, error) {
cfg, err := JWTConfigFromJSON(jsonKey)
if err != nil {
return nil, fmt.Errorf("google: could not parse JSON key: %v", err)
}
pk, err := internal.ParseKey(cfg.PrivateKey)
if err != nil {
return nil, fmt.Errorf("google: could not parse key: %v", err)
}
ts := &jwtAccessTokenSource{
email: cfg.Email,
audience: audience,
pk: pk,
}
tok, err := ts.Token()
if err != nil {
return nil, err
}
return oauth2.ReuseTokenSource(tok, ts), nil
}
// ComputeTokenSource returns a token source that fetches access tokens
// from Google Compute Engine (GCE)'s metadata server. It's only valid to use
// this token source if your program is running on a GCE instance.
// If no account is specified, "default" is used.
// Further information about retrieving access tokens from the GCE metadata
// server can be found at https://cloud.google.com/compute/docs/authentication.
func ComputeTokenSource(account string) oauth2.TokenSource {
return oauth2.ReuseTokenSource(nil, computeSource{account: account})
}
// TokenSource returns a JWT TokenSource using the configuration
// in c and the HTTP client from the provided context.
func (c *Config) TokenSource(ctx context.Context) oauth2.TokenSource {
return oauth2.ReuseTokenSource(nil, jwtSource{ctx, c})
}