Glance create API times out with copy_from header

[Gabriel Hurley]

The code in the create method goes through two discrete stages, the _reserve stage that creates the record, and the _handle_source stage that adds the image data to the store. When doing a copy-from operation, this can involve a very lengthy download which ties up the response causing socket timeouts, etc. for the API, especially when used from Horizon.

There's no reason that download can't happen asynchronously. Simply let the _handle_source method happen in its own thread and return a 202 Accepted from the API there.

The relevant bit to be spun off are the lines here: https://github.com/openstack/glance/blob/stable/essex/glance/api/v1/images.py#L544

[Eoghan Glynn (eglynn)]

The fix will involve an asynchronous copy-from, but not a 202 Accepted status code as suggested, since such a change to a non-error response would require a API version bump, see:

   http://wiki.openstack.org/APIChangeGuidelines

The status code from the image creation will continue to be 201 Created in all cases, with the initial image status reported as queued while the asynchronous copy-from is in progress.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/12438

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/12438
Committed: http://github.com/openstack/glance/commit/41c164139cab619d0a3e0d97b80037f85eb541ad
Submitter: Jenkins
Branch: master

commit 41c164139cab619d0a3e0d97b80037f85eb541ad
Author: Eoghan Glynn <email address hidden>
Date: Wed Sep 5 14:33:47 2012 +0000

    Asynchronously copy from external image source

    Fixes bug 1008874, bug 1046433.

    Avoid tieing up dispatch thread for large copy-from images,
    instead initiate copy asynchronously.

    The response status is not set to 202 Accepted as per standard
    RESTful idiom, as a non-error response code change requires
    an API version bump.

    Instead, the incomplete nature of the image registration is
    reflected in the image status.

    Change-Id: I06692422490de0a7d93f63bbd0ffb9c6435a0d2b