On Sep 25, 2015, at 1:24 PM, Brian Rosmaita <[email protected]> wrote: > > I'd like to clarify something. > > On 9/25/15, 12:16 PM, "Mark Voelker" <[email protected]> wrote: > [big snip] >> Also worth pointing out here: when we talk about ³doing the same thing² >> from a DefCore perspective, we¹re essentially talking about what¹s >> exposed to the end user, not how that¹s implemented in OpenStack¹s source >> code. So from an end user¹s perspective: >> >> If I call nova image-create, I get an image in my cloud. If I call the >> Glance v2 API to create an image, I also get an image in my cloud. I >> neither see nor care that Nova is actually talking to Glance in the >> background, because if I¹m writing code that uses the OpenStack API¹s, I >> need to pick which one of those two API¹s to make my code call upon to >> put an image in my cloud. Or, in the worst case, I have to write a bunch >> of if/else loops into my code because some clouds I want to use only >> allow one way and some allow only the other. > > The above is a bit inaccurate. > > The nova image-create command does give you an image in your cloud. The > image you get, however, is a snapshot of an instance that has been > previously created in Nova. If you don't have an instance, you cannot > create an image via that command. There is no provision in the Compute > (Nova) API to allow you to create an image out of bits that you supply. > > The Image (Glance) APIs (both v1 and v2) allow you to supply the bits and > register them as an image which you can then use to boot instances from by > using the Compute API. But note that if all you have available is the > Images API, you cannot create an image of one of your instances. > >> So from that end-user perspective, the Nova image-create API indeed does >> ³do the same thing" as the Glance API. > > They don't "do the same thing". Even if you have full access to the > Images v1 or v2 API, you will still have to use the Compute (Nova) API to > create an image of an instance, which is by far the largest use-case for > image creation. You can't do it through Glance, because Glance doesn't > know anything about instances. Nova has to know about Glance, because it > needs to fetch images for instance creation, and store images for > on-demand images of instances.
Yup, that’s fair: this was a bad example to pick (need moar coffee I guess). Let’s use image-list instead. =) At Your Service, Mark T. Voelker > > >> At Your Service, >> >> Mark T. Voelker > > Glad to be of service, too, > brian > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: [email protected]?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
