openstack team mailing list archive

[Brian Schott <bschott@xxxxxxx>]

On Feb 11, 2011, at 2:12 PM, Jay Pipes wrote:

> Hehe, sounds like something to chat about over a beer at the next
> design summit ;)

Looking forward to it... I enjoyed the last one.

> The issue isn't necessarily how to pass instance type, but how to pass
> *arbitrary* client request parameters, so I thought that user_data in
> the EC2 API was a good place for those, and was wondering (kinda out
> loud ;) ) what the best "field" or "place" would be on the OpenStack
> API side of things for that kind of arbitrary client request
> attribute..

For the EC2 API, I think that we're safer appending key-value pairs to instance_type field.  euca2ools just takes the string verbatim.  The problem with user_data is it is interpreted by existing images in all sorts of ways.  Like if "#!" is the first 2 characters, Ubuntu processes it as a bash shell script.  Very handy, bad to break.  Lots of cloud users depend on it working.  Most cloud development frameworks depend on unmolested user_data, since it is the only way to pass configuration data down to instances easily.  I can't think of any other field that makes sense from the EC2-centric perspective.  

Also want to stress to think about flavors/instance_types as "advertised" configurations, but that deployments might want to allow even these to be overridden.

---
Brian Schott, Project Leader
USC Information Sciences Institute
http://www.east.isi.edu/~bschott
ph: 703-812-3722 fx: 703-812-3712