<div dir="ltr">Hi, <div><br></div><div>I've been thinking a good bit on this on the right way to move forward with this and in general the right way new services should be added. Yesterday I was working on a bug that was causing some problems in the openstack infra. We tracked down the issue then I uploaded a patch for it. A little while later after jenkins voted back a -1 so I started looking through the logs to see what the source of the failure was (which was actually unrelated to my patch). The random failure in the fwaas/vpn/l3-agent code which all outputs to the same log file that contains many traces for every run even successful ones. In one skim of this log file I was able to spot 4 [1]bugs which shows these new "experimental" services that we've added to neutron have underlying problems (even though they've been in the tree for 2 releases+ now). This puts a huge strain on the whole openstack development community as they are always recheck no bug'ing due to neutron failures. </div>
<div><br></div><div>If you look at the fwaas work that was done. This merged over two releases ago and still does not have a complete API as there is no concept of where enforcement should be done. Today, enforcement is done across all of a tenant's routers making it more or less useless imho and we're just carrying it along in the tree (and it's causing us problems)!</div>
<div><br></div><div>I think Mark's idea of neutron-incubator[2] is a great step forward to improving neutron. </div><div><br></div><div>We can easily move these things out of the neutron source tree and we can plug these things in here: </div>
<div><a href="https://github.com/openstack/neutron/blob/master/etc/neutron.conf#L52">https://github.com/openstack/neutron/blob/master/etc/neutron.conf#L52</a><br></div><div><a href="https://github.com/openstack/neutron/blob/master/etc/neutron.conf#L72">https://github.com/openstack/neutron/blob/master/etc/neutron.conf#L72</a><br>
</div><div>(GASP: We have seen shipped our own API's here to customers before we were able to upstream them).</div><div><br></div><div>This allows us to decouple these experimental things from the neutron core and allows us to release these components on their own making things more modular/maintainable and stable (I think these things might even be better long term living out of the tree). Most importantly though it doesn't put a burden on everyone else. </div>
<div><br></div><div><br></div><div>Best, </div><div><br></div><div>Aaron</div><div><br></div><div><br></div><div>[1]</div><div><a href="http://paste.openstack.org/show/94664/">http://paste.openstack.org/show/94664/</a><br>
</div><div><a href="http://paste.openstack.org/show/94670/">http://paste.openstack.org/show/94670/</a><br></div><div><a href="http://paste.openstack.org/show/94663/">http://paste.openstack.org/show/94663/</a><br></div><div>
<a href="http://paste.openstack.org/show/94662/">http://paste.openstack.org/show/94662/</a><br></div><div><br></div><div>[2] - <a href="https://etherpad.openstack.org/p/neutron-incubator">https://etherpad.openstack.org/p/neutron-incubator</a><br>
</div><div><br></div><div><br></div><div><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Aug 11, 2014 at 9:58 AM, Robert Kukura <span dir="ltr"><<a href="mailto:kukura@noironetworks.com" target="_blank">kukura@noironetworks.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000"><div class="">
<br>
<div>On 8/8/14, 6:28 PM, Salvatore Orlando
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>"If we want to keep everything the way it is, we have to
change everything" [1]<br>
</div>
<div><br>
</div>
<div>This is pretty much how I felt after reading this
proposal, and I felt that this quote, which Ivar will
probably appreciate, was apt to the situation.</div>
<div>Recent events have spurred a discussion about the need
for a change in process. It is not uncommon indeed to
believe that by fixing the process, things will inevitably
change for better. While no-one argues that flaws in
processes need to be fixed, no process change will ever
change anything, in my opinion, unless it is aimed at
spurring change in people as well. </div>
<div><br>
</div>
<div>From what I understand, this proposal starts with the
assumption that any new feature which is committed to
Neutron (ie: has a blueprint approved), and is not a
required neutron component should be considered as a
preview. This is not different from the process, which,
albeit more informally, has been adopted so far. Load
Balancing, Firewall, VPN, have all been explicitly
documented as experimental in their first release; I would
argue that even if not experimental anymore, they may not be
considered stable until their stability was proven by
upstream QA with API and scenario tests - but this is not
sanctioned anywhere currently, I think.</div>
</div>
</div>
</blockquote></div>
Correct, this proposal is not so much a new process or change in
process as a formalization of what we've already been doing, and a
suggested adaptation to clarify the current expectations around
stability of new APIs.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div><br>
</div>
<div>According to this proposal, for preview features:</div>
<div>- all the code would be moved to a "preview" package</div>
</div>
</div>
</blockquote></div>
Yes.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Options will be marked as "preview"</div>
</div>
</div>
</blockquote></div>
Yes.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- URIs should be prefixed with "preview"</div>
</div>
</div>
</blockquote></div>
That's what I suggested, but, as several people have pointed out,
this does seem like its worth the cost of breaking the API
compatibility just at the point when it is being declared stable.
I'd like to withdraw this item.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- CLIs will note the features are "preview" in their help
strings</div>
</div>
</div>
</blockquote></div>
Yes.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Documentation will explicitly state this feature is
"preview" (I think we already mark them as experimental,
frankly I don't think there are a lot of differences in
terminology here)</div>
</div>
</div>
</blockquote></div>
Yes. Again to me, failure is one likely outcome of an "experiment".
The term "preview" is intended to imply more of a commitment to
quickly reach stability.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Database migrations will be in the main alembic path as
usual</div>
</div>
</div>
</blockquote></div>
Right.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- CLI, Devstack and Heat support will be available</div>
</div>
</div>
</blockquote></div>
Right, as appropriate for the feature.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Can be used by non-preview neutron code</div>
</div>
</div>
</blockquote></div>
No, I suggested "No non-preview Neutron code should import code from
anywhere under the neutron.preview module, ...".
<div class=""><blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Will undergo the usual review process</div>
</div>
</div>
</blockquote></div>
Right. This is key for the code to not have to jump through a new
major upheaval at right as it becomes stable.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- QA will be desirable, but will done either with "WIP"
tempest patches or merging the relevant scenario tests in
the preview feature iself</div>
</div>
</div>
</blockquote></div>
More than "desirable". We need a way to maintain and run the
tempest-like API and scenario tests during the stabilization
process, but to let then evolve with the feature.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- The feature might be promoted or removed, but the
process for this is not yet defined.</div>
</div>
</div>
</blockquote></div>
Any suggestions? I did try to address preventing long-term
stagnation of preview features. As a starting point, reviewing and
merging a patch that moves the code from the preview sub-tree to its
intended location could be a lightweight promotion process.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div><br>
</div>
<div>I don't think this change in process will actually
encourage better behaviour both by contributors and core
reviewers.</div>
</div>
</div>
</blockquote></div>
Encouraging better behavior might be necessary, but wasn't the main
intent of this proposal. This proposal was intended to clarify and
formalize the stability expectations around the initial releases of
new features. It was specifically intended to address the conundrum
currently faced by reviewers regarding patches that meet all
applicable quality standards, but may not yet have (somehow,
miraculously) achieved the maturity associated with stable APIs and
features fully supported for widespread deployment.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>I reckon that better behaviour might be encouraged by
forcing developer and reviewers to merge in the neutron
source code tree only code which meets the highest quality
standards. A change in process should enforce this - and
when I think about the criteria, I think at the same kind of
criteria we're being imposed to declare parity with nova.
Proven reliability, and scalability should be a must. Proven
usability should be a requirement for all new APIs.</div>
</div>
</div>
</blockquote></div>
I agree regarding the quality standards for merging of code, and am
not suggesting relaxing those one bit. But proving all of the
desirable system-level attributes of a complex new feature before
merging anything precludes any kind of iterative development
process. I think we should consider enforcing things like proven
reliability, scalability, and usability at the point where the
feature is promoted to stable rather than before merging the initial
patch.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>On the other hand we also need to avoid to over
bureaucratise Neutron - nobody loves that - and therefore
ensure this process is enforced only when really needed.</div>
<div><br>
</div>
<div>Looking at this proposal I see a few thing I'm not
comfortable with:</div>
<div>- having no clear criterion for exclusion a feature might
imply that will be silently bit-rotting code in the preview
package. Which what would happen for instance if we end up
with a badly maintained feature , but since one or two core
devs care about it, they'll keep vetoing the removal</div>
</div>
</div>
</blockquote></div>
First, the feature will never be considered inclusion in the preview
sub-tree without an initial approved blueprint and specification.
Second, I suggest we automatically remove a feature from the preview
tree after some small number of cycles, unless a new blueprint
detailing what needs to be done to complete stabilization is
approved.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- using the normal review process will still not solve
the problem of slow review cycles, pointless downvotes for
reviewers which actually just do not understand the subject
matter, and other pains associated with lack of interest
from small or large parts of the core team. For instance, I
think there is a line of pretty annoyed contributors as we
did not even bother reviewing their specs.</div>
</div>
</div>
</blockquote></div>
Agreed. But I'm hoping a clarified set of expectations for new
features will allow implementation, review, and merging of code for
approved blueprints to proceed incrementally, as is intended in our
current process, which will build up the familiarization of the team
with the new features as they are being developed.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- The current provision about QA seems to state that it's
ok to keep code in the main repo that does not adhere to
appropriate quality standards. Which is the mistake we did
with lbaas and other features, and I would like to avoid.
And to me it is not sufficient that the code is buried in
the 'preview' package.</div>
</div>
</div>
</blockquote></div>
Lowering code quality standards is definitely no part of the intent.
The preview code must be production-ready in order to be merged. Its
API and data model are just not yet declared stable.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div>- Mostly important, this process provides a justification
for contributors to push features which do not meet the same
standards as other neutron parts and expect them to be
merged and eventually promoted, and on the other hand
provides the core team with the entitlement for merging them
- therefore my main concern that it does not encourages
better behaviour in people, which should be the ultimate aim
of a process change.</div>
</div>
</div>
</blockquote></div>
I'm really confused by this interpretation of my proposal. Preview
code patches must go through the normal review process. Each
individual patch must meet all our normal standards. And the
system-level quality attributes of the feature must be proven as
well for the feature to be declared stable. But you can't prove
these system level attributes until you get the code into the hands
of early adopters and incorporate their feedback. Our current
process can facilitate this, as long as we set expectations properly
during this stabilization phase.<div class=""><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div><br>
</div>
<div>If you managed to read through all of this, and tolerated
my dorky literature references, I really appreciate your
patience, and would like to conclude that here we're
discussing proposals for a process change, whereas I expect
to discuss in the next neutron meeting the following:</div>
<div>- whether is acceptable to change the process now</div>
<div>- what did go wrong in our spec review process, as we
ended up with at least an approved spec which is actually
fiercely opposed by other core team members.</div>
</div>
</div>
</blockquote></div>
These discussions need to happen. I don't think my proposal should
be looked at as a major process change, but rather as a
clarification of how our current process explicitly supports
iterative development and stabilization of new features. It can be
applied to several of the new features targeted for Juno. Whether
there is actual opposition to the inclusion of any of these is a
separate matter, but some clarity about exactly what inclusion would
mean can't hurt that discussion.<br>
<br>
Thanks for your indulgence as well,<br>
<br>
-Bob<div><div class="h5"><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_extra">
<div><br>
</div>
<div>Have a good weekend,<br>
</div>
<div>Salvatore</div>
<div><br>
</div>
<div>[1] Quote from "Il Gattopardo" by Giuseppe Tomasi di
Lampedusa (english name: The Leopard)</div>
<div><br>
</div>
<br>
<div class="gmail_quote">
On 8 August 2014 22:21, Robert Kukura <span dir="ltr"><<a href="mailto:kukura@noironetworks.com" target="_blank">kukura@noironetworks.com</a>></span>
wrote:</div>
<div class="gmail_quote"><br>
</div>
<div class="gmail_quote">
<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">[Note
- I understand there are ongoing discussion that may lead
to a proposal for an out-of-tree incubation process for
new Neutron features. This is a complementary proposal
that describes how our existing development process can be
used to stabilize new features in-tree over the time frame
of a release cycle or two. We should fully consider both
proposals, and where each might apply. I hope something
like the approach I propose here will allow the
implementations of Neutron BPs with non-trivial APIs that
have been targeted for the Juno release to be included in
that release, used by early adopters, and stabilized as
quickly as possible for general consumption.]<br>
<br>
According to our existing development process, once a
blueprint and associated specification for a new Neutron
feature have been reviewed, approved, and targeted to a
release, development proceeds, resulting in a series of
patches to be reviewed and merged to the Neutron source
tree. This source tree is then the basis for milestone
releases and the final release for the cycle.<br>
<br>
Ideally, this development process would conclude
successfully, well in advance of the cycle's final
release, and the resulting feature and its API would be
considered fully "stable" in that release. Stable features
are ready for widespread general deployment. Going
forward, any further modifications to a stable API must be
backwards-compatible with previously released versions.
Upgrades must not lose any persistent state associated
with stable features. Upgrade processes and their impact
on a deployments (downtime, etc.) should be consistent for
all stable features.<br>
<br>
In reality, we developers are not perfect, and minor (or
more significant) changes may be identified as necessary
or highly desirable once early adopters of the new feature
have had a chance to use it. These changes may be
difficult or impossible to do in a way that honors the
guarantees associated with stable features.<br>
<br>
For new features that effect the "core" Neutron API and
therefore impact all Neutron deployments, the stability
requirement is strict. But for features that do not effect
the core API, such as services whose deployment is
optional, the stability requirement can be relaxed
initially, allowing time for feedback from early adopters
to be incorporated before declaring these APIs stable. The
key in doing this is to manage the expectations of
developers, packagers, operators, and end users regarding
these new optional features while they stabilize.<br>
<br>
I therefore propose that we manage these expectations,
while new optional features in the source tree stabilize,
by clearly labeling these features with the term "preview"
until they are declared stable, and sufficiently isolating
them so that they are not confused with stable features.
The proposed guidelines would apply during development as
the patches implementing the feature are first merged, in
the initial release containing the feature, and in any
subsequent releases that are necessary to fully stabilize
the feature.<br>
<br>
Here are my initial not-fully-baked ideas for how our
current process can be adapted with a "preview feature"
concept supporting in-tree stabilization of optional
features:<br>
<br>
* Preview features are implementations of blueprints that
have been reviewed, approved, and targeted for a Neutron
release. The process is intended for features for which
there is a commitment to add the feature to Neutron, not
for experimentation where "failing fast" is an acceptable
outcome.<br>
<br>
* Preview features must be optional to deploy, such as by
configuring a service plugin or some set of drivers.
Blueprint implementations whose deployment is not optional
are not eligible to be treated as preview features.<br>
<br>
* Patches implementing a preview feature are merged to the
the master branch of the Neutron source tree. This makes
them immediately available to all direct consumers of the
source tree, such as developers, trunk-chasing operators,
packagers, and evaluators or end-users that use DevStack,
maximizing the opportunity to get the feedback that is
essential to quickly stabilize the feature.<br>
<br>
* The process for reviewing, approving and merging patches
implementing preview features is exactly the same as for
all other Neutron patches. The patches must meet HACKING
standards, be production-quality code, have adequate test
coverage, have DB migration scripts, etc., and require two
+2s and a +A from Neutron core developers to merge.<br>
<br>
* DB migrations for preview features are treated similarly
to other DB migrations, forming a single ordered list that
results in the current overall DB schema, including the
schema for the preview feature. But DB migrations for a
preview feature are not yet required to preserve existing
persistent state in a deployment, as would be required for
a stable feature.<br>
<br>
* All code that is part of a preview feature is located
under neutron/preview/<feature>/. Associated unit
tests are located under neutron/tests/unit/preview/<feature>/,
and similarly for other test categories. This makes the
feature's status clear to developers and other direct
consumers of the source tree, and also allows packagers to
easily partition all preview features or individual
preview features into separate optionally installable
packages.<br>
<br>
* The tree structures underneath these locations should
make it straightforward to move the preview feature code
to its proper tree location once it is considered stable.<br>
<br>
* Tempest API and scenario tests for preview features are
highly desirable. We need to agree on how to accomplish
this without preventing necessary API changes. Posting WIP
patches to the Tempest project may be sufficient
initially. Putting Tempest-like tests in the Neutron tree
until preview features stabilize, then moving them to
Tempest when stabilization is complete, might be a better
long term solution.<br>
<br>
* No non-preview Neutron code should import code from
anywhere under the neutron.preview module, unless
necessary for special cases like DB migrations.<br>
<br>
* URIs for the resources provided by preview features
should contain the string "preview".<br>
<br>
* Configuration file content related to preview features
should be clearly labeled as "preview".<br>
<br>
* Preview features should be documented similarly to any
stable Neutron feature, but documents or sections of
documents related to preview features should have an
easily recognizable label that clearly identifies the
feature as a "preview".<br>
<br>
* Support for preview features in client libraries, and in
other projects such as Horizon, Heat, and DevStack, are
essential to get the feedback needed from early adopters
during feature stabilization. They are implemented
normally, but should be labeled "preview" appropriately,
such as in GUIs, in CLI help strings and in documentation
so that end user expectations regarding stability are
managed.<br>
<br>
* A process is needed to prevent long-term stagnation of
features in the preview sub-tree. It is reasonable to
expect a new feature to remain for one or two cycles,
possibly with little change (other than bug fixes), before
stabilizing. A suggested rule is that a new approved BP is
required after two cycles, or the feature gets removed
from the Neutron source tree (maybe moved (back) to an
incubation repository).<br>
<br>
<br>
I would appreciate feedback via this email thread on
whether this "preview feature" concept is worth further
consideration, refinement and potential usage for approved
feature blueprints, especially during the Juno cycle. I've
also posted the proposal text at <a href="https://etherpad.openstack.org/p/neutron-preview-features" target="_blank">https://etherpad.openstack.org/p/neutron-preview-features</a>
for those interested in helping refine the proposal.<br>
<br>
Thanks,<br>
<br>
-Bob<br>
<br>
<br>
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</blockquote>
</div>
<br>
</div>
</div>
<br>
<fieldset></fieldset>
<br>
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