Default-Image-Id

[Ian Booth]

>>
>> The documentation you refer to is for the old Python version of juju, which is
>> being replaced in 13.04 with a version written in Go. Both versions will be able
>> to co-exist but the Go version is the way forward. In the new version, the use
>> of default-image-id is currently deprecated as a means to explicitly choose a
>> specific image to run (that's *my* understanding at least).
> 
> I don't think it is deprecated, just not implemented.
> 
> Getting constraints right is a big hunk of work, and it is work in
> progress.  I think the development team is in agreement that we should
> support instance-id as a valid constraint as people will want it,
> however it is not currently implemented.
> 

Ah, in that case I have a branch up for review which provides a common
constraints framework for EC2 *and* Openstack and which allows for instance-id
to be specified but only as a fallback if all else fails. It will be easy to
tweak this so that it checks for instance-id first and uses that if specified.