def renew_token(self):
        """Convenience method: renew Vault token"""
        url = _url_joiner(self._vault_url, 'v1/auth/token/renew-self')
        resp = requests.get(url, headers=self._headers)
        resp.raise_for_status()
        data = resp.json()
        if data.get('errors'):
            raise VaultException(u'Error renewing Vault token: {}'.format(data['errors']))
        return data