machine placement spec

[Clint Byrum]

Excerpts from Nick Barcet's message of Tue Nov 22 09:17:34 -0800 2011:
> On 11/11/2011 03:56 PM, William Reade wrote:
> > Note that it is not advisable to implement co-location constraints
> > without having the ability to deploy units in isolated containers on
> > single machines; doing this is somewhat tricky.
> 
> Sorry if I am a little late to reply on this thread, but this
> (constraining co-location to separate containers) seems like something
> that should be optionally de-activated, as I'd really like us to use
> something like "place-with=<service-name>" which would deploy the
> service in the same container.
> 

This is covered as "subordinate services"

https://blueprints.launchpad.net/juju/+spec/subordinate-services

> For example, I would like to deploy an agent that would collect
> informations on [kvm, network, application specific logs, whatever] that
> is used/produced by <service-name>, and for this I am afraid it may not
> work if the two services are containerized.
> 
> We could of course include the agent deployment in the charm, but I
> think we would lose a lot in terms of flexibility.
> 
> Nick