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Hi,

I thought it would be a good idea to send out a status update for the
migration from nova-network to Neutron, as there hasn't been as much
progress as we'd hoped for in Kilo. There are a few issues which have
been slowing progress down.

First off, creating an all encompassing turn key upgrade is probably
not possible. This was also never a goal of this effort -- to quote
the spec for this work, "Consequently, the process described here is
not a “one size fits all” automated push-button tool but a series of
steps that should be obvious to automate and customise to meet local
needs" [1]. The variety of deployment and configuration options
available makes a turn key migration very hard to write, and possibly
impossible to test. We therefore have opted for writing "migration
tools", which allow operators to plug components together in the way
that makes sense for their deployment and then migrate using those.

However, talking to operators at the Ops Summit, is has become clear
that some operators simply aren't interested in moving to Neutron --
largely because they either aren't interested in tenant networks, or
have corporate network environments that make deploying Neutron very
hard. So, even if we provide migration tools, it is still likely that
we will end up with loyal nova-network users who aren't interested in
moving. From the Nova perspective, the end goal of all of this effort
is to delete the nova-network code, and if we can't do that because
some people simply don't want to move, then what is gained by putting
a lot of effort into migration tooling?

Therefore, there is some talk about spinning nova-network out into its
own project where it could continue to live on and be better
maintained than the current Nova team is able to do. However, this is
a relatively new idea and we haven't had a chance to determine how
feasible it is given where we are in the release cycle. I assume that
if we did this, we would need to find a core team passionate about
maintaining nova-network, and we would still need to provide some
migration tooling for operators who are keen to move to Neutron.
However, that migration tooling would be less critical than it is now.

Unfortunately, this has all come to a head at a time when the Nova
team is heads down getting the Kilo release out the door. We simply
don't have the time at the moment to properly consider these issues.
So, I'd like to ask for us to put a pause on this current work until
we have Kilo done. These issues are complicated and important, so I
feel we shouldn't rush them at a time we are distracted.

Finally, I want to reinforce that the position we currently find
ourselves in isn't because of a lack of effort. Oleg, Angus and Anita
have all worked very hard on this problem during Kilo, and it is
frustrating that we haven't managed to find a magic bullet to solve
all of these problems. I want to personally thank each of them for
their efforts this cycle on this relatively thankless task.

I'd appreciate other's thoughts on these issues.

Michael


1: http://specs.openstack.org/openstack/neutron-specs/specs/kilo/migration-from-nova-net.html#impact-limitations


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