[openstack-dev] [Heat][Oslo] Versioned objects compatibility mode

Davanum Srinivas davanum at gmail.com
Mon Jun 22 10:12:29 UTC 2015


we are adding that reread config to oslo.service, there's a test
version on pypi 0.1.0 (API not yet stable) that you can try and see if
it works for you.


On Mon, Jun 22, 2015 at 5:40 AM, Jastrzebski, Michal
<michal.jastrzebski at intel.com> wrote:
> Hello,
> I wanted to start discussion about versioned objects backporting for conductor-less projects.
> In Vancouver we discussed compatibility mode, which works like that:
> 1. We define one version for every object we use, this means adding base object, for example:
> Class HeatObject:
>         VERSION=1.5
> All objects inherit from this one, each time we change it, we bump up this variable.
> 2. We introduce new config option in heat.conf
> Combatibility_mode = 1.4
> 3. Implement mechanism which will automatically backport each outgoing message to 1.4 as long as we have this var.
> Upgrade flow looks like that:
> 1. We have all nodes using 1.4 version
> 2. We incrementally run new version with 1.4 compatibility mode
> 3. When all nodes are already up-to-date, we incrementally turn off compatibility mode
> This solution has one rather big disadvantage: 2 restarts.
> This can be mitigated by adding another call to reread config without restart. Oslo.config has this capability, but we need to add call to run it.
> Thoughts?
> Regards,
> Michał Jastrzębski
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Davanum Srinivas :: https://twitter.com/dims

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