Michal, hi, what's your assumption about instances? Do we want to shut
them down, migrate nova, and restart them or we'd like to preserve all
running VMs?
-marek
On 04.12.2015 21:50, Michał Jastrzębski wrote:
Hey guys,
Orchiestrated upgrades is one of our highest priorities for M in
kolla, so following up after discussion on summit I'd like to suggest
an approach:
Instead of creating playbook called "upgrade my openstack" we will
create "upgrade my nova" instead and approach to each service case by
case (since all of our running services are in dockers, this is possible).
We will also make use of image tags as version carriers, so ansible
will deploy new container only if version tag differs from what we ask
it to deploy. This will help with idempotency of upgrade process.
So let's start with nova. Upgrade-my-nova playbook will do something
like this:
0. We create snapshot of our mariadb-data container. This will affect
every service, but it's always good to have backup and rollback of db
will be manual action
1. Nova bootstrap will be called and it will perform db-migration.
Since current approach to nova code is add-only we shouldn't need to
stop services and old services should keep working on newer database.
Also for minor version upgrades there will be no action here unless
there is migration.
2. We upgrade all conductor at the same time. This should take mere
seconds since we'll have prebuilt containers
3. We will upgrade rest of controller services with using "series: 1"
in ansible to ensure rolling upgrades.
4. We will upgrade all of nova-compute services on it's own pace.
This workflow should be pretty robust (I think it is) and it should
also provide idempotency.
Thoughts?
Regards,
Michal
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Marek Zawadzki
Mirantis Kolla Team
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