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On 20/08/14 18:28, Salvatore Orlando wrote:
> Some comments inline.
> 
> Salvatore
> 
> On 20 August 2014 17:38, Ihar Hrachyshka <ihrachys at redhat.com 
> <mailto:ihrachys at redhat.com>> wrote:
> 
> Hi all,
> 
> I've read the proposal for incubator as described at [1], and I
> have several comments/concerns/suggestions to this.
> 
> Overall, the idea of giving some space for experimentation that
> does not alienate parts of community from Neutron is good. In that
> way, we may relax review rules and quicken turnaround for preview
> features without loosing control on those features too much.
> 
> Though the way it's to be implemented leaves several concerns, as 
> follows:
> 
> 1. From packaging perspective, having a separate repository and 
> tarballs seems not optimal. As a packager, I would better deal with
> a single tarball instead of two. Meaning, it would be better to
> keep the code in the same tree.
> 
> I know that we're afraid of shipping the code for which some users
> may expect the usual level of support and stability and
> compatibility. This can be solved by making it explicit that the
> incubated code is unsupported and used on your user's risk. 1) The
> experimental code wouldn't probably be installed unless explicitly
> requested, and 2) it would be put in a separate namespace (like
> 'preview', 'experimental', or 'staging', as the call it in Linux
> kernel world [2]).
> 
> This would facilitate keeping commit history instead of loosing it 
> during graduation.
> 
> Yes, I know that people don't like to be called experimental or 
> preview or incubator... And maybe neutron-labs repo sounds more 
> appealing than an 'experimental' subtree in the core project.
> Well, there are lots of EXPERIMENTAL features in Linux kernel that
> we actively use (for example, btrfs is still considered
> experimental by Linux kernel devs, while being exposed as a
> supported option to RHEL7 users), so I don't see how that naming
> concern is significant.
> 
> 
>> I think this is the whole point of the discussion around the
>> incubator and the reason for which, to the best of my knowledge,
>> no proposal has been accepted yet.
> 

I wonder where discussion around the proposal is running. Is it public?

> 
> 2. If those 'extras' are really moved into a separate repository
> and tarballs, this will raise questions on whether packagers even
> want to cope with it before graduation. When it comes to supporting
> another build manifest for a piece of code of unknown quality, this
> is not the same as just cutting part of the code into a separate 
> experimental/labs package. So unless I'm explicitly asked to
> package the incubator, I wouldn't probably touch it myself. This is
> just too much effort (btw the same applies to moving plugins out of
> the tree - once it's done, distros will probably need to reconsider
> which plugins they really want to package; at the moment, those
> plugins do not require lots of time to ship them, but having ~20
> separate build manifests for each of them is just too hard to
> handle without clear incentive).
> 
> 
>> One reason instead for moving plugins out of the main tree is
>> allowing their maintainers to have full control over them. If
>> there was a way with gerrit or similars to give somebody rights
>> to merge code only on a subtree I probably would not even
>> consider the option of moving plugin and drivers away. From my
>> perspective it's not that I don't want them in the main tree,
>> it's that I don't think it's fair for core team reviewers to take
>> responsibility of approving code that they can't fully tests (3rd
>> partt CI helps, but is still far from having a decent level of
>> coverage).
> 

I agree with that. I actually think that moving vendor plugins outside
the main tree AND rearranging review permissions and obligations
should be extremely beneficial to the community. I'm totally for that
as quick as possible (Kilo please!) Reviewers waste their time
reviewing plugins that are in most cases interesting for a tiny
fraction of operators. Let the ones that are primarily interested in
good quality of that code (vendors) to drive development. And if some
plugins become garbage, it's bad news for specific vendors; if neutron
screws because of lack of concentration on core features and open
source plugins, everyone is doomed.

Of course, splitting vendor plugins into separate repositories will
make life of packagers a bit harder, but the expected benefits from
such move are huge, so - screw packagers on this one. :)

Though the way incubator is currently described in that proposal on
the wiki doesn't clearly imply similar benefits for the project, hence
concerns.

> 
> 
> 3. The fact that neutron-incubator is not going to maintain any
> stable branches for security fixes and major failures concerns me
> too. In downstream, we don't generally ship the latest and greatest
> from PyPI. Meaning, we'll need to maintain our own downstream
> stable branches for major fixes. [BTW we already do that for python
> clients.]
> 
> 
>> This is a valid point. We need to find an appropriate trade off.
>> My thinking was that incubated projects could be treated just
>> like client libraries from a branch perspective.
> 

Clients assume some level of backwards compatibility, so upgrades are
generally assumed to be smooth; and the whole point of incubator is
NOT providing any such guarantees, which makes updating packages to
the newly released version from PyPI too scary for distributions. All
in all, we already maintain stable client branches for RDO:
http://openstack.redhat.com/Clients I guess we'll need the same for
incubator, if we decide to package it.

> 
> 
> 4. Another unclear part of the proposal is that notion of keeping 
> Horizon and client changes required for incubator features in 
> neutron-incubator. AFAIK the repo will be governed by Neutron Core 
> team, and I doubt the team is ready to review Horizon changes (?).
> I think I don't understand how we're going to handle that. Can we
> just postpone Horizon work till graduation?
> 
> 
>> I too do not think it's a great idea, mostly because there will
>> be horizon bits not shipped with horizon, and not verified by
>> horizon core team. I think it would be ok to have horizon support
>> for neutron incubator. It won't be the first time that support
>> for experimental features is added in horizon.

You mean, in the main horizon tree?

> 
> 
> 5. The wiki page says that graduation will require full test
> coverage. Does it mean 100% coverage in 'coverage' report? I don't
> think our existing code is even near that point, so maybe it's not
> fair to require that from graduated code.
> 
> 
>> I agree that by these standards we should take the whole neutron
>> and return it to incubation, or probably just chuck it in the
>> bin. It's not a mystery that Neutron quality is well below
>> integrated level but let's not diverge.
> 
>> On the other hand, the fact that Neutron's code is rubbish does
>> not authorise the addition of further rubbish. I see this
>> requirement for graduation as a measure to ensure new additions
>> to neutron have proper quality. In the meanwhile it will be
>> mandatory for the neutron community to keep working on quality,
>> scalability and improve testing coverage. Otherwise there will be
>> no talk about neutron-incubator, mostly because probably there
>> will be no neutron.
> 

Of course, we should raise the bar for all the code - already merged,
in review, and in incubator. I just think there is no reason to make
those requirements different from general acceptance requirements (do
we have those formally defined?).

> 
> A separate tree would probably be reasonable if it would be
> governed by a separate team. But as it looks now, it's still
> Neutron Cores who will do the review heavy-lifting. So I wonder why
> not just applying different review rules for patches for core and
> the staging subtree.
> 
> 
>> This is a good point. As a neutron core I don't want to do the
>> heavy lifting there. I think we should define rules which allow
>> teams to iterate quickly while enabling the neutron core team to
>> retain some form of control on what goes in the incubator.
> 
> 
> [1]: https://wiki.openstack.org/wiki/Network/Incubator [2]: 
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/staging
>
>  /Ihar
> 
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