[openstack-dev] [Neutron] Getting project version from API

Armando M. armamig at gmail.com
Mon Jun 6 11:03:12 UTC 2016

On 6 June 2016 at 10:06, Oleg Bondarev <obondarev at mirantis.com> wrote:

> Hi,
> There are cases where it would be useful to know the version of Neutron
> (or any other project) from API, like during upgrades or in cross-project
> communication cases.
> For example in https://review.openstack.org/#/c/246910/ Nova needs to
> know if Neutron sends vif-plugged event during live migration. To ensure
> this it should be enough to know Neutron is "Newton" or higher.
> Not sure why it wasn't done before (or was it and I'm just blind?) so the
> question to the community is what are possible issues/downsides of exposing
> code version through the API?

If you are not talking about features exposed through the API (for which
they'd have a new extension being advertised), knowing that you're running
a specific version of the code might not guarantee that a particular
feature is available, especially in the case where the capability is an
implementation detail that is config tunable (evil, evil). This may also
lead to needless coupling between the two projects, as you'd still want to
code defensively and assume the specific behavior may or may not be there.

I suspect that your case is slightly different in that the lack of a
received event may be due to an error rather than a missing capability and
you would not be able to distinguish the difference if not optimistically
assume lack of capability. Then you need to make a "mental" note and come
back to the code to assume a failure two cycles down the road from when
your code merges. Definitely not a pretty workflow without advertising the
new feature explicitly via the API.

> Thanks,
> Oleg
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