[openstack-dev] [Heat] Long-term, how do we make heat image/flavor name agnostic?

Robert Collins robertc at robertcollins.net
Thu Jul 18 10:08:34 UTC 2013

On 18 July 2013 08:53, Gabriel Hurley <Gabriel.Hurley at nebula.com> wrote:
> I spent a bunch of time working with and understanding Heat in H2, and I find myself with one overarching question which I wonder if anyone's thought about or even answered already...
> At present, the CloudFormation template format is the first-class means of doing things in Heat. CloudFormation was created for Amazon, and Amazon has this massive convenience of having a (more or less) static list of images and flavors that they control. Therefore in CloudFormation everything is specified by a unique, specific name.
> OpenStack doesn't have this luxury. We have as many image and flavor names as we have deployments. Now, there are simple answers...
>   1. Name everything the way Amazon does, or
>   2. Alter your templates.
> But personally, I don't like either of these options. I think in the long term we win at platform/ecosystem by making it possible to take a template off the internet and having it work on *any* OpenStack cloud.
> To get there, we need a system that chooses images based on metadata (platform, architecture, distro) and flavors based on actual minimum requirements.

We do? Why do we?

Note that your characterisation of Amazon is in my experience
inaccurate - a very common pattern there is uploading custom images
(such as those that we build for OpenStack using diskimage-builder).
An OpenStack cloud should let users upload their own images to glance
in the same way, and then you have 3): use golden images, name your
personal images the same in every cloud you burst to; done.

Also note that the presence of golden images makes a 'just fit the
broad characteristics' a more complex problem than perhaps you think
it is... You need some additional 'is it the right built image' aspect

So I would tackle this using 4) provide a mapping layer that bridges
template to cloud and lets you translate:
 - image names
 - flavours
 - keypair
 - perhaps volumes and other things


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Cloud Services

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