[Openstack] Cross-zone instance identifiers in EC2 API - Is it worth the effort?

Ewan Mellor Ewan.Mellor at eu.citrix.com
Tue Jul 12 01:53:31 UTC 2011



> -----Original Message-----
> From: Sandy Walsh [mailto:sandy.walsh at RACKSPACE.COM]
> Sent: 11 July 2011 17:10
> To: Ewan Mellor; Ed Leafe; Eric Day
> Cc: openstack at lists.launchpad.net
> Subject: RE: [Openstack] Cross-zone instance identifiers in EC2 API -
> Is it worth the effort?
> 
> From: Ewan Mellor [Ewan.Mellor at eu.citrix.com]
> 
> > If so, then I would say that your proposed limitation above is not
> acceptable.  We don't want a situation where tenants have to stop using
> the EC2 API as soon as their service provider wants to offer a rich set
> of offerings.
> 
> Hmm, two concerns here:
> 
> 1. What's the alternative? Should we "embrace and extend" EC2 API to
> ensure compatibility with OS API?

No, I was expecting that we could squeeze this through the existing EC2 API.  The service provider could have instance types that mapped to service offerings: superfastnetworking.large or xenserver.medium or whatever, as opposed to EC2's m1.small, etc.  I hope that most clients are written expecting the instance types to change over time (Amazon have added instance types themselves in the past).

Embrace and extend definitely isn't going to work.  You can only do that if you are the big guy.  Little old OpenStack won't be able to bully the EC2 ecosystem.

> 2. Could we not have plain vanilla EC2 at the top-level zone and do all
> the funky stuff under the hood, mapping EC2 artifacts to OS artifacts
> as needed? If EC2 wants 8-character with a prefix, we can map it to our
> UUID's across Zones, but with obvious limitations. If EC2 runs out of
> space in their identifiers, that's that. Either start using the OS API
> or use a new shard. We play the game ... to a point. When it no longer
> makes sense we don't try to put a square peg in a round hole.
> 
> Same argument goes for OCCI, Bob's Cloud Mart and whatever other API's
> show up down the road.
> 
> At first blush I don't think there's really any reason why we can't
> make the top-level Zone look and feel like an EC2 deployment?

I'm not close enough to the code to make an assessment, but I agree with you.  At first blush, it doesn't look like it should be impossible.

> Having EC2 API (even 80% compatible) allows them to dip their toes in
> the water without a large engineering effort to re-tool. Ideally, re-
> point their URL to a Nova install and play around. If they like what
> they see, they can slowly migrate away from the limitations of the EC2
> world and join the party. This was the Nova vision all along, no?
> Incremental development vs. boil-the-ocean. As a consumer of cloud
> services, that sounds like a pretty compelling argument to me.

I agree 100%.  This is what I want.

Ewan.





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