[openstack-dev] Solving the client libs stable support dilemma

Sean Dague sean at dague.net
Thu Nov 20 02:23:51 UTC 2014

On 11/19/2014 08:55 PM, Brant Knudson wrote:
> On Mon, Nov 17, 2014 at 8:51 AM, Doug Hellmann <doug at doughellmann.com
> <mailto:doug at doughellmann.com>> wrote:
>     On Nov 17, 2014, at 6:16 AM, Sean Dague <sean at dague.net
>     <mailto:sean at dague.net>> wrote:
>     > On 11/16/2014 11:23 AM, Doug Hellmann wrote:
>     >>
>     >> On Nov 16, 2014, at 9:54 AM, Jeremy Stanley <fungi at yuggoth.org
>     <mailto:fungi at yuggoth.org>> wrote:
>     >>
>     >>> On 2014-11-16 09:06:02 -0500 (-0500), Doug Hellmann wrote:
>     >>>> So we would pin the client libraries used by the servers and
>     >>>> installed globally, but then install the more recent client
>     >>>> libraries in a virtualenv and test using those versions?
>     >>>
>     >>> That's what I was thinking anyway, yes.
>     >>>
>     >>>> I like that.
>     >>>
>     >>> Honestly I don't, but it sucks less than the other solutions which
>     >>> sprang to mind. Hopefully someone will come along with a more
>     >>> elegant suggestion... in the meantime I don't see any obvious
>     >>> reasons why it wouldn't work.
>     >>
>     >> Really, it’s a much more accurate test of what we want. We
>     have, as an artifact of our test configuration, to install
>     everything on a single box. But what we’re trying to test is that
>     a user can install the new clients and talk to an old cloud. We
>     don’t expect deployers of old clouds to install new clients — at
>     least we shouldn’t, and by pinning the requirements we can make
>     that clear. Using the virtualenv for the new clients gives us
>     separation between the “user” and “cloud” parts of the test
>     configuration that we don’t have now.
>     >>
>     >> Anyway, if we’re prepared to go along with this I think it’s
>     safe for us to stop using alpha version numbers for Oslo libraries
>     as a matter of course. We may still opt to do it in cases where we
>     aren’t sure of a new API or feature, but we won’t have to do it
>     for every release.
>     >>
>     >> Doug
>     >
>     > I think this idea sounds good on the surface, though what a working
>     > system looks like is going to be a little interesting to make
>     sure you
>     > are in / out of the venv.
>     >
>     > I actually think you might find it simpler to invert this.
>     >
>     > Create 1 global venv for servers, specify the venv before
>     launching a
>     > service.
>     >
>     > Install all the clients into system level space, then running
>     nova list
>     > doesn't require that it is put inside the venv.
>     >
>     > This should have the same results, but be less confusing for people
>     > poking at devstacks manually.
>     That makes sense. I’m a little worried that it’s a bigger change
>     to devstack vs. the job that’s testing the clients, but I’ll defer
>     to you on what’s actually easier since you’re more familiar with
>     the code. Either way, installing the servers and the clients into
>     separate packaging spaces would allow us to pin the clients in the
>     stable branches.
> Another piece is middleware, for example the auth_token middleware in
> the keystonemiddleware package.

Right, so that would get dragged into the system libs for the CLI pieces
at whatever the clients want, and would get additionally dragged into
the global venv for the server based on the server's needs. I think the
only question would be if LIBS_FROM_GIT did both system and global venv
in this case. Perhaps we'd need another SYSLIBS_FROM_GIT or something to
specify the differences.

Anyway, I think I have most of the ideas in my head, but will write all
this out in a spec before implementing, because there are probably
enough edge cases that we'll want plenty of eyes looking at it.


Sean Dague

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