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On 8/13/18 9:47 PM, Giulio Fidente wrote:
> Hello,
> 
> I'd like to get some feedback regarding the remaining
> work for the split controlplane spec implementation [1]
> 
> Specifically, while for some services like nova-compute it is not
> necessary to update the controlplane nodes after an edge cloud is
> deployed, for other services, like cinder (or glance, probably
> others), it is necessary to do an update of the config files on the
> controlplane when a new edge cloud is deployed.
> 
> In fact for services like cinder or glance, which are hosted in the
> controlplane, we need to pull data from the edge clouds (for example
> the newly deployed ceph cluster keyrings and fsid) to configure cinder
> (or glance) with a new backend.
> 
> It looks like this demands for some architectural changes to solve the > following two:
> 
> - how do we trigger/drive updates of the controlplane nodes after the
> edge cloud is deployed?

Note, there is also a strict(?) requirement of local management 
capabilities for edge clouds temporary disconnected off the central 
controlplane. That complicates the updates triggering even more. We'll 
need at least a notification-and-triggering system to perform required 
state synchronizations, including conflicts resolving. If that's the 
case, the architecture changes for TripleO deployment framework are 
inevitable AFAICT.

> 
> - how do we scale the controlplane parameters to accomodate for N
> backends of the same type?
> 
> A very rough approach to the latter could be to use jinja to scale up
> the CephClient service so that we can have multiple copies of it in the
> controlplane.
> 
> Each instance of CephClient should provide the ceph config file and
> keyring necessary for each cinder (or glance) backend.
> 
> Also note that Ceph is only a particular example but we'd need a similar
> workflow for any backend type.
> 
> The etherpad for the PTG session [2] touches this, but it'd be good to
> start this conversation before then.
> 
> 1.
> https://specs.openstack.org/openstack/tripleo-specs/specs/rocky/split-controlplane.html
> 
> 2. https://etherpad.openstack.org/p/tripleo-ptg-queens-split-controlplane
> 


-- 
Best regards,
Bogdan Dobrelya,
Irc #bogdando