[openstack-dev] [kolla][nova] Orchiestrated upgrades in kolla

Marek Zawadzki mzawadzki at mirantis.com
Thu Dec 17 11:59:42 UTC 2015

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?


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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