[openstack-dev] [heat] Rolling Upgrades

Crag Wolfe cwolfe at redhat.com
Sat Oct 22 00:06:41 UTC 2016


On 10/21/2016 11:25 AM, Crag Wolfe wrote:
> Another edge case is that if only the first h-engine is upgraded during
> a rolling upgrade and the operator waits awhile before upgrading the
> other h-engines, we'll have a case where we are not distributing newer
> rpc calls as much as we'd like. Specifically, that first h-engine is
> sending newer messages that only get picked up by itself, in addition to
> it picking up older h-engine messages. I'm not sure what to do about
> that other than to suggest "don't do that."

This may be a key case to consider. We'll have to go with major/minor
version pinning and take the future_args route if we can't risk the
above scenario (short of the full blown "RPC version reporting and
detection framework" Michal provided). I.e., the rpc version is pinned
at 1.36 and new args are migrated through future_args, until the next
major version release.

--Crag



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