Hi Michael, and thank you for your answer.
Indeed, what I want to do is to add methods to the ImageCache.py module (listing, adding, deleting). So far, this module only takes care of image deletion: this represents the "cache" of images. Now, I want to populate the cache with some images on the hypervisor (as you mention) without having any instance running it, yet. The method I want like to add should call the appropriate method from the hypervisor driver (let's say libvirt) to trigger the image download/creation without starting it (I guess something like calling _create_image() should do the trick). Your question is actually good: how will an user be able to trigger this image caching mechanism? My idea is to extend the HTTP Nova Compute API. I would lilke to add a resource, let's say "CachedImages", to the API tree. In this way, interacting via CRUD operation we should be able to CALL/CAST rpc api and interact with the imagecache module. Is it clearer now? Do you see any problem in this approach? Regards, Alberto. On Thu, Oct 8, 2015 at 11:45 PM, Michael Still <mi...@stillhq.com> wrote: > I think I'd rephrase your definition of pre-fetched to be honest -- > something more like "images on this hypervisor node without a currently > running instance". So, your operations would become: > > - trigger an image prefetching > - list unused base images (and perhaps when they were last used) > - delete an unused image > > All of that would need to tie into the image cache management code so that > its not stomping on your images. In fact, you're probably best of adding > all of this as tweaks to the image cache manager anyways. > > One question though -- who is calling these APIs? Are you adding a central > service to orchestrate these calls? > > Michael > > > > On Thu, Oct 8, 2015 at 10:50 PM, Alberto Geniola <albertogeni...@gmail.com > > wrote: > >> Hi all, >> >> I'm considering to extend the Nova-Compute API in order to provide >> image-prefetching capabilities to OS. >> >> In order to allow image prefetching, I ended up with the need to add >> three different APIs on the nova-compute nodes: >> >> 1. Trigger an image prefetching >> >> 2. List prefetched images >> >> 3. Delete a prefetched image >> >> >> >> About the point 1 I saw I can re-use the libvirt driver function >> _create_image() to trigger the image prefetching. However, this approach >> will not store any information about the stored image locally. This leads >> to an issue: how do I retrieve a list of already fetched images? A quick >> and simple possibility would be having a local file, storing information >> about the fetched images. Would it be acceptable? Is there any best >> practice in OS community? >> >> >> >> Any ideas? >> >> >> Ty, >> >> Al. >> >> -- >> Dott. Alberto Geniola >> >> albertogeni...@gmail.com >> +39-346-6271105 >> https://www.linkedin.com/in/albertogeniola >> >> Web: http://www.hw4u.it >> >> __________________________________________________________________________ >> OpenStack Development Mailing List (not for usage questions) >> Unsubscribe: >> openstack-dev-requ...@lists.openstack.org?subject:unsubscribe >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >> >> > > > -- > Rackspace Australia > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > -- Dott. Alberto Geniola albertogeni...@gmail.com +39-346-6271105 https://www.linkedin.com/in/albertogeniola Web: http://www.hw4u.it
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