Open Stack

The nova.image.download.modules extension point was added back in Havana:

https://review.openstack.org/#/c/37817/

Looks like there was some related work in Glance after the Grizzly summit:

https://blueprints.launchpad.net/glance/+spec/multiple-image-locations

This all looks related to the direct image download features that some 
Rbd-backed deployments are using for fast snapshots.

Anyway, the configuration options used with the extension point were 
deprecated in nova in the Newton release:

https://review.openstack.org/#/c/314669/

That refers to some vague understanding that this was POC code added to 
Nova for Rackspace (by a Red Hat developer?) but was never used in 
production and we can just deprecate and remove it from Nova.

Since I'm a bit worried about vague assertions about who is doing what 
with this, I'd like to give the operators a chance to say if they are 
using this direct file scheme image download extension point at all, or 
if not the in-tree one, at least an out of tree plugin for the 
nova.image.download.modules extension point as that will happily load up 
any download handler as long as nova can import the module, there is no 
whitelist of support handlers.

I also know that lots of deployments probably aren't at Newton yet so 
they haven't seen the release notes about the image_file_url config 
options being deprecated so I wanted this to be a further heads up 
before we go and remove this code.

-- 

Thanks,

Matt Riedemann