openstack shaker-image的build

在shaker的官方文档中，有手动build shaker-image的步骤，但一开始提示如下错误：

Building elements: base ubuntu vm shakerERROR: Element 'pip-and-virtualenv' not found in 'shaker/shaker/resources/image_elements:/usr/bin/../share/diskimage-builder/elements'

而去掉shaker后则提示：/usr/sbin/grub-install: error: embedding is not possible, but this is required for cross-disk install.

后发现ubuntu16.0.4自带的diskimage-builder版本为1.0.0，遂通过pip install -U diskimage-builder进行升级。

镜像builder成功