Spec Lite: Add new container format¶
- project:
glance
- problem:
Compression method using hardware to accelerate has already been implemented in cinder project. A new container format ‘compressed’ needs to be added to container format list in glance to support this.
- solution:
A new container format ‘compressed’ option needs to be added to the default container_format configuration list.
- impacts:
New container format option
- how:
If users chose to upload volume using compression method, cinder will do compression and then upload to glance. The uploaded image’s metadata will be ‘compressed’ in container_format so that it can be correctly processed after downloaded. Volume disk_format will not be changed by this compression process.
Glance will not handle the compression and decompression progress, which means glance will not check if it is a vaild compressed image. Whoever is to upload or download the image is responsible for compression or decompression.
Uploaded image will not be automatically compressed if simply changing the container_format as ‘compressed’. Compression or decompression happens when image is uploading from volume or downloading to a volume.
Glance will not identify what format the compressed image really is. In glance’s view, it is just a blob. Image consumer (such as cinder) will identify the real format such as gzip, rar or other format.
- other impact:
Nova cannot currently handle images in a compressed container format. We propose patching Nova to reject such images: https://review.opendev.org/#/c/673407/
- timeline:
Include in train release
- link:
- assignee:
ZhengMa
