Open Stack

Ahoy folks,

So we've been running into issues with the addition of the cell v2
setup as part of the requirements for different parts of nova.  It was
recommended that we move the conversation to the ML to get a wider
audience.  Basically, cell v2 has been working it's way into a
required thing for various parts of nova for the Ocata cycle.  We've
hit several issues[0][1] because of this.  I put a wider audience than
just nova because deployment tools need to understand how this works
as it impacts anyone installing or upgrading.

What is not clear is what is the expectation around how to install and
configure cell v2.  When we hit the first bug in the upgrade, we
reached out in irc[2] around this and it seemed that there was little
to no documentation around how this stuff all works.  There are
mentions of these new commands in the release notes[3] but it's not
clear on the specifics for both the upgrade process and also a fresh
install.  We attempted to just run simple_cell_setup in the puppet
(and tripleo downstream) because we assumed this would handle all the
things.  It's become clear that this is not the case.  The latest
bug[1] has shown that we do not have a proper understanding of what it
means to setup cell v2, so I'd like to use this email to start the
conversation as it impacts anyone either install Ocata fresh or
attempting some sort of Newton -> Ocata upgrade.

Additionally after some conversations today on irc[4], it's also
become clear there is some disconnect around understanding between
nova folks and people who deploy as to how this thing would ideally
work.  So, what I would like to know is how should people be
installing and configuring nova cell v2? Specifically what are the
steps so that the deployment tools and operators can properly handle
these complexities.  What are the assumptions being baked into
simple_cell_setup?  It seems to assume computes should exist before
the cell simple setup where as traditionally computes are the last
thing to be setup (for new installs).

So, help?

Thanks,
-Alex

[0] https://bugs.launchpad.net/tripleo/+bug/1649341
[1] https://bugs.launchpad.net/nova/+bug/1656276
[2] http://eavesdrop.openstack.org/irclogs/%23openstack-nova/%23openstack-nova.2016-12-12.log.html#t2016-12-12T17:38:56
[3] http://docs.openstack.org/releasenotes/nova/unreleased.html#id12
[4] http://eavesdrop.openstack.org/irclogs/%23openstack-nova/%23openstack-nova.2017-01-13.log.html#t2017-01-13T14:11:37