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Hi,

I'm hitting an issue with v2 api upload() and not sure the best way to
fix it so would appreciate some opinions/suggestions.

https://bugs.launchpad.net/glance/+bug/1213880
https://bugs.launchpad.net/python-glanceclient/+bug/1220197

So, currently doing cinder upload-to-image fails with v2 glance api and
RBD backend store. This is because v2 uses upload() (as opposed to
update() in v1) and does not accept an image-size. The v2 Glance api
upload() implementation checks the request content-length (which is
currently always zero) and then tries to create an RBD image of size
zero then write to it which fails. I have tried different solutions:

1. if image size is zero, resize for each chunk then write.

2. set content-length in glanceclient to size of image

Problem with 1 is that this implicitly disables 'Transfer-Encoding:
chunked' i.e. disables chunking. Problem with 2 is you get 2RTT of
network latency per write plus overhead of a resize.

So, I now think the best way to do this would be to modify the update
call to allow the glancelcient to send x-image-meta-size so that the
backend knows how big the image will be, create the image then write the
chunk(s) incrementally (kind of like the swift store).

Suggestions?

Ed.