Adding remote image in v2 when cache is enabled results 500 error

[Mike Fedosin]

To reproduce the issue:

1) Add an image without specifying the size
2) Enable caching
3) Get image data. This will succeed because the Content-Length is pulled from the remote store (i.e. swift). At this point, the image will be properly cached.
4) Get image data again with v2 api. This will fail with 500 error http://paste.openstack.org/show/483545/

It happens for the reason cache middleware couldn't assign value to image_meta['size'] because it expects a dictionary (as it was in v1 api), but in v2 api it's ImageTarget object.

[Mike Fedosin (mfedosin)]

Related bug for v1: https://bugs.launchpad.net/glance/+bug/900959

[Stuart McLaren (stuart-mclaren)]

Co-incidently, this is what I was hitting when testing https://review.openstack.org/#/c/254873

  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/mnt/opt/stack/glance/glance/common/wsgi.py", line 588, in __call__
    response = req.get_response(self.application)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1317, in send
    application, catch_exc_info=False)
  File "/usr/local/lib/python2.7/dist-packages/webob/request.py", line 1281, in call_application
    app_iter = application(self.environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 130, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 195, in call_func
    return self.func(req, *args, **kwargs)
  File "/mnt/opt/stack/glance/glance/common/wsgi.py", line 585, in __call__
    response = self.process_request(req)
  File "/mnt/opt/stack/glance/glance/api/middleware/cache.py", line 171, in process_request
    return method(request, image_id, image_iterator, image_metadata)
  File "/mnt/opt/stack/glance/glance/api/middleware/cache.py", line 226, in _process_v2_request
    self._verify_metadata(image_meta)
  File "/mnt/opt/stack/glance/glance/api/middleware/cache.py", line 75, in _verify_metadata
    image_meta['size'] = self.cache.get_image_size(image_meta['id'])
 TypeError: 'ImageTarget' object does not support item assignment

[Stuart McLaren (stuart-mclaren)]

So download of a standard zero size image can hit this also.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/266891

[OpenStack Infra (hudson-openstack)]

Change abandoned by Darja Shakhray (<email address hidden>) on branch: master
Review: https://review.openstack.org/266891
Reason: This commit is not necessary

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ian Cordasco (<email address hidden>) on branch: master
Review: https://review.openstack.org/269277
Reason: As discussed on the other patch, this is unnecessary