openstack team mailing list archive

[Michael Basnight <mbasnight@xxxxxxxxx>]

On Apr 10, 2012, at 6:19 PM, Angus Salkeld wrote:

> On 10/04/12 15:36 -0700, Justin Santa Barbara wrote:
>>> 
>>> The immediate use case I have in mind is to support this:
>>> http://wiki.openstack.org/**PackageConfigForNova<http://wiki.openstack.org/PackageConfigForNova>.  That design requires periodic checkins between an instance agent and a
>>> nova driver.  It certainly /could/ be implemented using ssh, but I
>>> originally wrote the design imagining there was a ready-made, standard
>>> communication service, and I still think it would be convenient.
>>> 
>> 
>> My concern with that proposal is that it starts simple enough, but then
>> when you want to know e.g. "was the package installed successfully? is the
>> service healthy?" then you need more and more complexity i.e. you end up
>> with PlatformLayer, RedDwarf, Heat, Puppet, Chef or Juju.  So putting a
>> small piece of the required functionality into nova doesn't address your
>> actual use case, which is "I want configured machines, not just the stock
>> images".  It's probably easier to put that logic into your management
>> system of choice, so nova shouldn't do it.  Am I off base here?
> 
> Yea, that seem odd. Isn't that what your tool above + cloud-init is for?
> Looks like a layering violation of some kind.

I know im a bit late to the party but i totally agree with Justin. This kind of stuff tends to bleed into Platform related tasks, not something that an IaaS service like nova would/should perform. Reddwarf gets around it by having a small python guest installed on the VM. It currently uses a rabbit cluster for communication. Be forewarned, Im not saying that rabbit is the ideal communication channel for this job! We have looked into xmpp and metadata svc if it can meet our needs. We've talked about guests and communication for the last 3 summits and i guess we might be doing the same again this time :D