VMware: booting multiple instances fails if image is not in cache

[Tracy Jones]

If you try to boot several VMs with a new image (which does not exist in the cache) all instances will fail until the 1st instance downloads the image to cache.

Since the nova boot commands are being handled async, the 1st one will start downloading the image to cache and the others will "think" that the image is there (since only the meta-data file is checked). This is a side affect of bug

https://bugs.launchpad.net/nova/+bug/1213269

The "workaround" is to always deploy an instance when a new image is added to glance. But the real fix should be 2 parts

1. make checking is the file is in cache more robust - i.e. validate the file is completely there (not just the meta data file)

2. if an image is in the middle of being downloaded to the cache, block the other instances at that point until the image download is complete.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/46400

[Tracy Jones (tjones-i)]

this bug has been fixed by https://review.openstack.org/#/c/54096/