By default, Werkzeug would require the entire file (be it an OVA or
image file) to be uploaded and saved to a temporary, fake file under
`/tmp`, before any further processing could occur. This blocked most of
the execution of these functions until the upload was completed.
This entirely defeated the purpose of what I was trying to do, which was
to save the uploads directly to the temporary blockdev in each case,
thus avoiding any sort of memory or (host) disk usage.
The solution is two-fold:
1. First, ensure that the `location='args'` value is set in
RequestParser; without this, the `files` portion would be parsed
during the argument parsing, which was the original source of this
blocking behaviour.
2. Instead of the convoluted request handling that was being done
originally here, instead entirely defer the parsing of the `files`
arguments until the point in the code where they are ready to be
saved. Then, using an override stream_factory that simply opens the
temporary blockdev, the upload can commence while being written
directly out to it, rather than using `/tmp` space.
This does alter the error handling slightly; it is impossible to check
if the argument was passed until this point in the code, so it may take
longer to fail if the API consumer does not specify a file as they
should. This is a minor trade-off and I would expect my API consumers to
be sane here.
Doing so can create an image that is 1 sector (512 bytes) too large,
which will then break qemu-img because it's stupid (or, VMDK is stupid,
I haven't decided which is).. Current Ceph rbd commands seem to accept
--size in bytes so this is fine.
Ensure all API return messages are formated the same: no "error", a
final period except when displaying Exception text, and a regular spaced
out format.
Add functions for uploading, listing, and removing OVA images to the API
and CLI interfaces. Includes improved parsing of the OVF and creation of
a system_template and profile for each OVA.
Also modifies some behaviour around profiles, making most components
option at creation to support both profile types (and incomplete
profiles generally).
Implementation part 2/3 - remaining: OVA VM creation
References #71
Joshua Boniface