Open Stack

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?

- 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

-- 
Giulio Fidente
GPG KEY: 08D733BA