[kolla-ansible] migration

Ignazio Cassano ignaziocassano at gmail.com
Thu Jun 27 11:10:36 UTC 2019

Many thanks.
I hope you'll write come docs at the end

Il Gio 27 Giu 2019 10:52 Mark Goddard <mark at stackhpc.com> ha scritto:

> On Wed, 26 Jun 2019 at 19:34, Ignazio Cassano <ignaziocassano at gmail.com>
> wrote:
> >
> > Hello,
> > Anyone have tried to migrate an existing openstack installation to kolla
> containers?
> Hi,
> I'm aware of two people currently working on that. Gregory Orange and
> one of my colleagues, Pierre Riteau. Pierre is away currently, so I
> hope he doesn't mind me quoting him from an email to Gregory.
> Mark
> "I am indeed working on a similar migration using Kolla Ansible with
> Kayobe, starting from a non-containerised OpenStack deployment based
> on CentOS RPMs.
> Existing OpenStack services are deployed across several controller
> nodes and all sit behind HAProxy, including for internal endpoints.
> We have additional controller nodes that we use to deploy
> containerised services. If you don't have the luxury of additional
> nodes, it will be more difficult as you will need to avoid processes
> clashing when listening on the same port.
> The method I am using resembles your second suggestion, however I am
> deploying only one containerised service at a time, in order to
> validate each of them independently.
> I use the --tags option of kolla-ansible to restrict Ansible to
> specific roles, and when I am happy with the resulting configuration I
> update HAProxy to point to the new controllers.
> As long as the configuration matches, this should be completely
> transparent for purely HTTP-based services like Glance. You need to be
> more careful with services that include components listening for RPC,
> such as Nova: if the new nova.conf is incorrect and you've deployed a
> nova-conductor that uses it, you could get failed instances launches.
> Some roles depend on others: if you are deploying the
> neutron-openvswitch-agent, you need to run the openvswitch role as
> well.
> I suggest starting with migrating Glance as it doesn't have any
> internal services and is easy to validate. Note that properly
> migrating Keystone requires keeping existing Fernet keys around, so
> any token stays valid until the time it is expected to stop working
> (which is fairly complex, see
> https://bugs.launchpad.net/kolla-ansible/+bug/1809469).
> While initially I was using an approach similar to your first
> suggestion, it can have side effects since Kolla Ansible uses these
> variables when templating configuration. As an example, most services
> will only have notifications enabled if enable_ceilometer is true.
> I've added existing control plane nodes to the Kolla Ansible inventory
> as separate groups, which allows me to use the existing database and
> RabbitMQ for the containerised services.
> For example, instead of:
> [mariadb:children]
> control
> you may have:
> [mariadb:children]
> oldcontrol_db
> I still have to perform the migration of these underlying services to
> the new control plane, I will let you know if there is any hurdle.
> A few random things to note:
> - if run on existing control plane hosts, the baremetal role removes
> some packages listed in `redhat_pkg_removals` which can trigger the
> removal of OpenStack dependencies using them! I've changed this
> variable to an empty list.
> - compare your existing deployment with a Kolla Ansible one to check
> for differences in endpoints, configuration files, database users,
> service users, etc. For Heat, Kolla uses the domain heat_user_domain,
> while your existing deployment may use another one (and this is
> hardcoded in the Kolla Heat image). Kolla Ansible uses the "service"
> project while a couple of deployments I worked with were using
> "services". This shouldn't matter, except there was a bug in Kolla
> which prevented it from setting the roles correctly:
> https://bugs.launchpad.net/kolla/+bug/1791896 (now fixed in latest
> Rocky and Queens images)
> - the ml2_conf.ini generated for Neutron generates physical network
> names like physnet1, physnet2… you may want to override
> bridge_mappings completely.
> - although sometimes it could be easier to change your existing
> deployment to match Kolla Ansible settings, rather than configure
> Kolla Ansible to match your deployment."
> > Thanks
> > Ignazio
> >
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