$client->getHandlerList()->appendSign(function (callable $handler) {
      return function (CommandInterface $command, RequestInterface $request = null) use ($handler) {
        return $handler($command, $request)->then(null, function(DynamoDbException $ex) {
          // Log the exception
          $response = json_decode($ex->getResponse()->getBody(), true);
          $request = $ex->getRequest();

          $this->getLogger()->log(sprintf(
            'message=%s&operation=%s&requestBody=%s&response=%s',
            urlencode($ex->getMessage()),
            urlencode($request->getHeaderLine('x-amz-target')),
            urlencode($request->getBody()),
            urlencode($response['message'])
          ), LOG_ERR);
        });
      };
    });