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Re: Allowing clients to pass capability requests through tags?


We have to keep in mind, that any additions to ec2_api will by definition be a hack.  We should attempt to support it as best we can, but consider how we would like things to work on a grander scale.

We are currently discussing two different sets of tags:
1. the type of instance to create. (local storage gb, gpu enabled, architecture, etc.)
2. where to create the image (near object x, in a certain zone, on a specific host, etc.)

I think both of these items are valuable, and perhaps in the os api they could be passed in all together.  From the ec2 perspective, I think that the "best" option would be to put type-related tags into the -t field, and location related flags into the -z field.

In any case, we need to be able to specify whether the tag is required or a suggestion (as in should the request fail if the tag cannot be fulfilled)


On Feb 11, 2011, at 11:42 AM, Brian Schott wrote:

> 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
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