def get_token(self):
        """Returns a client token from Cerberus"""
        signed_headers = self._get_v4_signed_headers()
        for header in self.HEADERS:
            signed_headers[header] = self.HEADERS[header]

        resp = post_with_retry(self.cerberus_url + '/v2/auth/sts-identity', headers=signed_headers)
        throw_if_bad_response(resp)

        token = resp.json()['client_token']
        iam_principal_arn = resp.json()['metadata']['aws_iam_principal_arn']
        if self.verbose:
            print('Successfully authenticated with Cerberus as {}'.format(iam_principal_arn), file=sys.stderr)
        logger.info('Successfully authenticated with Cerberus as {}'.format(iam_principal_arn))

        return token
Returns a client token from Cerberus