[openstack-dev] [Solum/Heat] Is Solum really necessary?

Adrian Otto adrian.otto at rackspace.com
Thu Nov 14 19:06:17 UTC 2013


Thanks for the great question. They really are different.

Heat's mission (correct me if there is a more recent one) is:

"To explicitly model the relationships between OpenStack resources of all kinds; and to harness those models, expressed in forms accessible to both humans and machines, to manage infrastructure resources throughout the lifecycle of applications."

Solum is about three things that are largely outside the scope of that mission:

Developer Productivity
Application Portability
Language / Application Stack Flexibility and Tooling / Add-On Extensibility

These are explained further on the wiki[1]. 

The key difference is a focus on an Application as an entity, and how it integrates with the application developer's workflow. It's a way to make OpenStack clouds more attractive for Application Developers. Things like integration with CI, gating, and promotion through environments is where Solum is concerned. We want Application Developers to be able to deploy code to openstack *without* modeling their application in a template (for the general case) and have that template generated for them.

Why focus on making life easy for Application Developers? Because this is a key to the future of the OpenStack user community. Operators of OpenStack Clouds want to be able to serve that market, and currently struggle to fill this gap, both for private and public cloud use cases.

The parts of Solum that overlap with Heat actually come directly from Heat, because Solum treats Heat as an upstream component. It's an explicit goal to not reproduce functionality in Solum that's already in OpenStack, but provide an integration point to allow specific focus on this important area. The goals around making applications of various languages easy to build and run on OpenStack Clouds are things that are definitely beyond the scope of what Heat is intended for. For example, Heat has no concept of a build service.

The list of differences extends beyond what I mentioned above, but those are the key ones. We contribute to both projects, so we don't view it as competitive at all. We see them as complimentary.


[1] https://wiki.openstack.org/wiki/Solum

On Nov 14, 2013, at 10:41 AM, Jay Pipes <jaypipes at gmail.com>

> So while I have been on vacation, I've been thinking about Solum and Heat.
> And I have some lingering questions in my mind that make me question whether a new server project is actually necessary at all, and whether we really should just be targeting innovation and resources towards the Heat project.
> What exactly is Solum's API going to control that is not already represented in Heat's API and the HOT templating language? At this point, I'm really not sure, and I'm hoping that we can discuss this important topic before going any further with Solum. Right now, I see so much overlap that I'm questioning where the differences really are.
> Thoughts?
> -jay
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