..
      Licensed under the Apache License, Version 2.0 (the "License"); you may
      not use this file except in compliance with the License. You may obtain
      a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

      Unless required by applicable law or agreed to in writing, software
      distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
      WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
      License for the specific language governing permissions and limitations
      under the License.

.. _process:

=================
Nova team process
=================

Nova is always evolving its processes, but it's important to explain why we
have them: so we can all work to ensure that the interactions we need to
happen do happen. The process exists to make productive communication between
all members of our community easier.

OpenStack Wide Patterns
=======================

Nova follows most of the generally adopted norms for OpenStack projects.
You can get more details here:

* https://docs.openstack.org/infra/manual/developers.html
* https://docs.openstack.org/project-team-guide/

If you are new to Nova, please read this first: :ref:`getting_involved`.

Dates overview
==============

For Yoga, please see:
https://wiki.openstack.org/wiki/Nova/Yoga_Release_Schedule

.. note:: Throughout this document any link which references the name of a
          release cycle in the link can usually be changed to the name of the
          current cycle to get up to date information.

Feature Freeze
~~~~~~~~~~~~~~

Feature freeze primarily provides a window of time to help the horizontal
teams prepare their items for release, while giving developers time to
focus on stabilising what is currently in master, and encouraging users
and packagers to perform tests (automated, and manual) on the release, to
spot any major bugs.

The Nova release process is aligned with the `development cycle schedule
<https://docs.openstack.org/project-team-guide/release-management.html#typical-development-cycle-schedule>`_
used by many OpenStack projects, including the following steps.

- Feature Proposal Freeze

  -  make sure all code is up for review
  -  so we can optimise for completed features, not lots of half
     completed features

- Feature Freeze

  -  make sure all feature code is merged

- String Freeze

  -  give translators time to translate all our strings

  .. note::

    debug logs are no longer translated

- Dependency Freeze

  -  time to co-ordinate the final list of dependencies, and give packagers
     time to package them
  -  generally it is also quite destabilising to take upgrades (beyond
     bug fixes) this late

As with all processes here, there are exceptions. The exceptions at
this stage need to be discussed with the horizontal teams that might be
affected by changes beyond this point, and as such are discussed with
one of the OpenStack release managers.

Spec and Blueprint Approval Freeze
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is a (mostly) Nova specific process.

Why we have a Spec Freeze:

-  specs take a long time to review and reviewing specs throughout the cycle
   distracts from code reviews
-  keeping specs "open" and being slow at reviewing them (or just
   ignoring them) annoys the spec submitters
-  we generally have more code submitted that we can review, this time
   bounding is a useful way to limit the number of submissions

By the freeze date, we expect all blueprints that will be approved for the
cycle to be listed on launchpad and all relevant specs to be merged.
For Yoga, blueprints can be found at
https://blueprints.launchpad.net/nova/yoga and specs at
https://specs.openstack.org/openstack/nova-specs/specs/yoga/index.html

Starting with Liberty, we are keeping a backlog open for submission at all
times.

.. note::

  The focus is on accepting and agreeing problem statements as being in scope,
  rather than queueing up work items for the next release. We are still
  working on a new lightweight process to get out of the backlog and approved
  for a particular release. For more details on backlog specs, please see:
  http://specs.openstack.org/openstack/nova-specs/specs/backlog/index.html

There can be exceptions, usually it's an urgent feature request that
comes up after the initial deadline. These will generally be discussed
at the weekly Nova meeting, by adding the spec or blueprint to discuss
in the appropriate place in the meeting agenda here (ideally make
yourself available to discuss the blueprint, or alternatively make your
case on the ML before the meeting):
https://wiki.openstack.org/wiki/Meetings/Nova#Agenda_for_next_meeting

String Freeze
~~~~~~~~~~~~~

String Freeze provides an opportunity for translators to translate user-visible
messages to a variety of languages. By not changing strings after the date of
the string freeze, the job of the translators is made a bit easier. For more
information on string and other OpenStack-wide release processes see `the
release management docs
<http://docs.openstack.org/project-team-guide/release-management.html>`_.

How do I get my code merged?
============================

OK, so you are new to Nova, and you have been given a feature to
implement. How do I make that happen?

You can get most of your questions answered here:

-  https://docs.openstack.org/infra/manual/developers.html

But let's put a Nova specific twist on things...

Overview
~~~~~~~~

.. image:: /_static/images/nova-spec-process.svg
   :alt: Flow chart showing the Nova bug/feature process

Where do you track bugs?
~~~~~~~~~~~~~~~~~~~~~~~~

We track bugs here:

-  https://bugs.launchpad.net/nova

If you fix an issue, please raise a bug so others who spot that issue
can find the fix you kindly created for them.

Also before submitting your patch it's worth checking to see if someone
has already fixed it for you (Launchpad helps you with that, at little,
when you create the bug report).

When do I need a blueprint vs a spec?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For more details refer to :doc:`/contributor/blueprints`.

To understand this question, we need to understand why blueprints and
specs are useful.

But here is the rough idea:

-  if it needs a spec, it will need a blueprint.
-  if it's an API change, it needs a spec.
-  if it's a single small patch that touches a small amount of code,
   with limited deployer and doc impact, it probably doesn't need a
   spec.

If you are unsure, please ask the `PTL`_ on IRC, or one of the other
nova-drivers.

How do I get my blueprint approved?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So you need your blueprint approved? Here is how:

-  if you don't need a spec, please add a link to your blueprint to the
   agenda for the next nova meeting:
   https://wiki.openstack.org/wiki/Meetings/Nova

   -  be sure your blueprint description has enough context for the
      review in that meeting.

-  if you need a spec, then please submit a nova-spec for review, see:
   https://docs.openstack.org/infra/manual/developers.html

Got any more questions? Contact the `PTL`_ or one of the other
nova-specs-core who are awake at the same time as you. IRC is best as
you will often get an immediate response, if they are too busy send
him/her an email.

How do I get a procedural -2 removed from my patch?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When feature freeze hits, any patches for blueprints that are still in review
get a procedural -2 to stop them merging. In Nova a blueprint is only approved
for a single release. To have the -2 removed, you need to get the blueprint
approved for the current release (see `How do I get my blueprint approved?`_).

Why are the reviewers being mean to me?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Code reviews take intense concentration and a lot of time. This tends to
lead to terse responses with very little preamble or nicety. That said,
there's no excuse for being actively rude or mean. OpenStack has a Code
of Conduct (https://www.openstack.org/legal/community-code-of-conduct/)
and if you feel this has been breached please raise the matter
privately. Either with the relevant parties, the `PTL`_ or failing those,
the OpenStack Foundation.

That said, there are many objective reasons for applying a -1 or -2 to a
patch:

-  Firstly and simply, patches must address their intended purpose
   successfully.
-  Patches must not have negative side-effects like wiping the database
   or causing a functional regression. Usually removing anything,
   however tiny, requires a deprecation warning be issued for a cycle.
-  Code must be maintainable, that is it must adhere to coding standards
   and be as readable as possible for an average OpenStack developer
   (we acknowledge that this person is not easy to define).
-  Patches must respect the direction of the project, for example they
   should not make approved specs substantially more difficult to
   implement.
-  Release coordinators need the correct process to be followed so scope
   can be tracked accurately. Bug fixes require bugs, features require
   blueprints and all but the simplest features require specs. If there
   is a blueprint, it must be approved for the release/milestone the
   patch is attempting to merge into.

Please particularly bear in mind that a -2 does not mean "never ever"
nor does it mean "your idea is bad and you are dumb". It simply means
"do not merge today". You may need to wait some time, rethink your
approach or even revisit the problem definition but there is almost
always some way forward. The core who applied the -2 should tell you
what you need to do.

My code review seems stuck, what can I do?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

First and foremost - address any -1s and -2s! The review load on Nova is
high enough that patches with negative reviews often get filtered out
entirely. A few tips:

-  Be precise. Ensure you're not talking at cross purposes.
-  Try to understand where the reviewer is coming from. They may have a
   very different perspective and/or use-case to you.
-  If you don't understand the problem, ask them to explain - this is
   common and helpful behaviour.
-  Be positive. Everyone's patches have issues, including core
   reviewers. No-one cares once the issues are fixed.
-  Try not to flip-flop. When two reviewers are pulling you in different
   directions, stop pushing code and negotiate the best way forward.
-  If the reviewer does not respond to replies left on the patchset,
   reach out to them on IRC or email. If they still don't respond, you
   can try to ask their colleagues if they're on holiday (or simply
   wait). Finally, you can ask for mediation in the Nova meeting by
   adding it to the agenda
   (https://wiki.openstack.org/wiki/Meetings/Nova). This is also what
   you should do if you are unable to negotiate a resolution to an
   issue.

Secondly, Nova is a big project, look for things that have been waiting
a long time for a review:
https://review.opendev.org/#/q/project:openstack/nova+status:open+age:2weeks

Eventually you should get some +1s from people working through the
review queue. Expect to get -1s as well. You can ask for reviews within
your company, 1-2 are useful (not more), especially if those reviewers
are known to give good reviews. You can spend some time while you wait
reviewing other people's code - they may reciprocate and you may learn
something (:ref:`Why do code reviews when I'm not core? <why_plus1>`).

If you've waited an appropriate amount of time and you haven't had any
+1s, you can ask on IRC for reviews. Please don't ask for core review
straight away, especially not directly (IRC or email). Core reviewer
time is very valuable and gaining some +1s is a good way to show your
patch meets basic quality standards.

Once you have a few +1s, be patient. Remember the average wait times.
You can ask for reviews each week in IRC, it helps to ask when cores are
awake.

Bugs
^^^^

It helps to apply correct tracking information.

-  Put "Closes-Bug", "Partial-Bug" or "Related-Bug" in the commit
   message tags as necessary.
-  If you have to raise a bug in Launchpad first, do it - this helps
   someone else find your fix.
-  Make sure the bug has the correct `priority`_ and `tag`_ set.

.. _priority: https://wiki.openstack.org/wiki/BugTriage#Task_2:_Prioritize_confirmed_bugs_.28bug_supervisors.29
.. _tag: https://wiki.openstack.org/wiki/Nova/BugTriage#Tags

Features
^^^^^^^^

Again, it helps to apply correct tracking information. For
blueprint-only features:

-  Put your blueprint in the commit message, EG "blueprint
   simple-feature".
-  Mark the blueprint as NeedsCodeReview if you are finished.
-  Maintain the whiteboard on the blueprint so it's easy to understand
   which patches need reviews.
-  Use a single topic for all related patches. All patches for one
   blueprint should share a topic.

For blueprint and spec features, do everything for blueprint-only
features and also:

-  Ensure your spec is approved for the current release cycle.

If your code is a project or subteam priority, the cores interested in
that priority might not mind a ping after it has sat with +1s for a
week. If you abuse this privilege, you'll lose respect.

If it's not a priority, your blueprint/spec has been approved for the
cycle and you have been patient, you can raise it during the Nova
meeting. The outcome may be that your spec gets unapproved for the
cycle, so that priority items can take focus. If this happens to you,
sorry - it should not have been approved in the first place, Nova team
bit off more than they could chew, it is their mistake not yours. You
can re-propose it for the next cycle.

If it's not a priority and your spec has not been approved, your code
will not merge this cycle. Please re-propose your spec for the next
cycle.

Nova Process Mission
====================

This section takes a high level look at the guiding principles behind
the Nova process.

Open
~~~~

Our mission is to have:

-  Open Source
-  Open Design
-  Open Development
-  Open Community

We have to work out how to keep communication open in all areas. We need
to be welcoming and mentor new people, and make it easy for them to
pickup the knowledge they need to get involved with OpenStack. For more
info on Open, please see: https://wiki.openstack.org/wiki/Open

Interoperable API, supporting a vibrant ecosystem
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An interoperable API that gives users on-demand access to compute
resources is at the heart of :ref:`nova's mission <nova-mission>`.

Nova has a vibrant ecosystem of tools built on top of the current Nova
API. All features should be designed to work with all technology
combinations, so the feature can be adopted by our ecosystem. If a new
feature is not adopted by the ecosystem, it will make it hard for your
users to make use of those features, defeating most of the reason to add
the feature in the first place. The microversion system allows users to
isolate themselves

This is a very different aim to being "pluggable" or wanting to expose
all capabilities to end users. At the same time, it is not just a
"lowest common denominator" set of APIs. It should be discoverable which
features are available, and while no implementation details should leak
to the end users, purely admin concepts may need to understand
technology specific details that back the interoperable and more
abstract concepts that are exposed to the end user. This is a hard goal,
and one area we currently don't do well is isolating image creators from
these technology specific details.

Smooth Upgrades
~~~~~~~~~~~~~~~

As part of our mission for a vibrant ecosystem around our APIs, we want
to make it easy for those deploying Nova to upgrade with minimal impact
to their users. Here is the scope of Nova's upgrade support:

-  upgrade from any commit, to any future commit, within the same major
   release
-  only support upgrades between N and N+1 major versions, to reduce
   technical debt relating to upgrades

Here are some of the things we require developers to do, to help with
upgrades:

-  when replacing an existing feature or configuration option, make it
   clear how to transition to any replacement
-  deprecate configuration options and features before removing them

   -  i.e. continue to support and test features for at least one
      release before they are removed
   -  this gives time for operator feedback on any removals

-  End User API will always be kept backwards compatible

Interaction goals
~~~~~~~~~~~~~~~~~

When thinking about the importance of process, we should take a look at:
http://agilemanifesto.org

With that in mind, let's look at how we want different members of the
community to interact. Let's start with looking at issues we have tried
to resolve in the past (currently in no particular order). We must:

-  have a way for everyone to review blueprints and designs, including
   allowing for input from operators and all types of users (keep it
   open)
-  take care to not expand Nova's scope any more than absolutely
   necessary
-  ensure we get sufficient focus on the core of Nova so that we can
   maintain or improve the stability and flexibility of the overall
   codebase
-  support any API we release approximately forever. We currently
   release every commit, so we're motivated to get the API right the first
   time
-  avoid low priority blueprints that slow work on high priority work,
   without blocking those forever
-  focus on a consistent experience for our users, rather than ease of
   development
-  optimise for completed blueprints, rather than more half completed
   blueprints, so we get maximum value for our users out of our review
   bandwidth
-  focus efforts on a subset of patches to allow our core reviewers to
   be more productive
-  set realistic expectations on what can be reviewed in a particular
   cycle, to avoid sitting in an expensive rebase loop
-  be aware of users that do not work on the project full time
-  be aware of users that are only able to work on the project at
   certain times that may not align with the overall community cadence
-  discuss designs for non-trivial work before implementing it, to avoid
   the expense of late-breaking design issues

FAQs
====

Why bother with all this process?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We are a large community, spread across multiple timezones, working with
several horizontal teams. Good communication is a challenge and the
processes we have are mostly there to try and help fix some
communication challenges.

If you have a problem with a process, please engage with the community,
discover the reasons behind our current process, and help fix the issues
you are experiencing.

Why don't you remove old process?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We do! For example, in Liberty we stopped trying to predict the
milestones when a feature will land.

As we evolve, it is important to unlearn new habits and explore if
things get better if we choose to optimise for a different set of
issues.

Why are specs useful?
~~~~~~~~~~~~~~~~~~~~~

Spec reviews allow anyone to step up and contribute to reviews, just
like with code. Before we used gerrit, it was a very messy review
process, that felt very "closed" to most people involved in that
process.

As Nova has grown in size, it can be hard to work out how to modify Nova
to meet your needs. Specs are a great way of having that discussion with
the wider Nova community.

For Nova to be a success, we need to ensure we don't break our existing
users. The spec template helps focus the mind on the impact your change
might have on existing users and gives an opportunity to discuss the
best way to deal with those issues.

However, there are some pitfalls with the process. Here are some top
tips to avoid them:

-  keep it simple. Shorter, simpler, more decomposed specs are quicker
   to review and merge much quicker (just like code patches).
-  specs can help with documentation but they are only intended to
   document the design discussion rather than document the final code.
-  don't add details that are best reviewed in code, it's better to
   leave those things for the code review.

If we have specs, why still have blueprints?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We use specs to record the design agreement, we use blueprints to track
progress on the implementation of the spec.

Currently, in Nova, specs are only approved for one release, and must be
re-submitted for each release you want to merge the spec, although that
is currently under review.

Why do we have priorities?
~~~~~~~~~~~~~~~~~~~~~~~~~~

To be clear, there is no "nova dev team manager", we are an open team of
professional software developers, that all work for a variety of (mostly
competing) companies that collaborate to ensure the Nova project is a
success.

Over time, a lot of technical debt has accumulated, because there was a
lack of collective ownership to solve those cross-cutting concerns.
Before the Kilo release, it was noted that progress felt much slower,
because we were unable to get appropriate attention on the architectural
evolution of Nova. This was important, partly for major concerns like
upgrades and stability. We agreed it's something we all care about and
it needs to be given priority to ensure that these things get fixed.

Since Kilo, priorities have been discussed at the summit. This turns in
to a spec review which eventually means we get a list of priorities
here: http://specs.openstack.org/openstack/nova-specs/#priorities

Allocating our finite review bandwidth to these efforts means we have to
limit the reviews we do on non-priority items. This is mostly why we now
have the non-priority Feature Freeze. For more on this, see below.

Blocking a priority effort is one of the few widely acceptable reasons
to block someone adding a feature. One of the great advantages of being
more explicit about that relationship is that people can step up to help
review and/or implement the work that is needed to unblock the feature
they want to get landed. This is a key part of being an Open community.

Why is there a Feature Freeze (and String Freeze) in Nova?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The main reason Nova has a feature freeze is that it allows people
working on docs and translations to sync up with the latest code.
Traditionally this happens at the same time across multiple projects, so
the docs are synced between what used to be called the "integrated
release".

We also use this time period as an excuse to focus our development
efforts on bug fixes, ideally lower risk bug fixes, and improving test
coverage.

In theory, with a waterfall hat on, this would be a time for testing and
stabilisation of the product. In Nova we have a much stronger focus on
keeping every commit stable, by making use of extensive continuous
testing. In reality, we frequently see the biggest influx of fixes in
the few weeks after the release, as distributions do final testing of
the released code.

It is hoped that the work on Feature Classification will lead us to
better understand the levels of testing of different Nova features, so
we will be able to reduce and dependency between Feature Freeze and
regression testing. It is also likely that the move away from
"integrated" releases will help find a more developer friendly approach
to keep the docs and translations in sync.

Why is there a non-priority Feature Freeze in Nova?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We have already discussed why we have priority features.

The rate at which code can be merged to Nova is primarily constrained by
the amount of time able to be spent reviewing code. Given this,
earmarking review time for priority items means depriving it from
non-priority items.

The simplest way to make space for the priority features is to stop
reviewing and merging non-priority features for a whole milestone. The
idea being developers should focus on bug fixes and priority features
during that milestone, rather than working on non-priority features.

A known limitation of this approach is developer frustration. Many
developers are not being given permission to review code, work on bug
fixes or work on priority features, and so feel very unproductive
upstream. An alternative approach of "slots" or "runways" has been
considered, that uses a kanban style approach to regulate the influx of
work onto the review queue. We are yet to get agreement on a more
balanced approach, so the existing system is being continued to ensure
priority items are more likely to get the attention they require.

Why do you still use Launchpad?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We are actively looking for an alternative to Launchpad's bugs and
blueprints.

Originally the idea was to create Storyboard. However development
stalled for a while so interest waned. The project has become more active
recently so it may be worth looking again:
https://storyboard.openstack.org/#!/page/about

When should I submit my spec?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ideally we want to get all specs for a release merged before the summit.
For things that we can't get agreement on, we can then discuss those at
the summit. There will always be ideas that come up at the summit and
need to be finalised after the summit. This causes a rush which is best
avoided.

How can I get my code merged faster?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So no-one is coming to review your code, how do you speed up that
process?

Firstly, make sure you are following the above process. If it's a
feature, make sure you have an approved blueprint. If it's a bug, make
sure it is triaged, has its priority set correctly, it has the correct
bug tag and is marked as in progress. If the blueprint has all the code
up for review, change it from Started into NeedsCodeReview so people
know only reviews are blocking you, make sure it hasn't accidentally got
marked as implemented.

Secondly, if you have a negative review (-1 or -2) and you responded to
that in a comment or uploading a new change with some updates, but that
reviewer hasn't come back for over a week, it's probably a good time to
reach out to the reviewer on IRC (or via email) to see if they could
look again now you have addressed their comments. If you can't get
agreement, and your review gets stuck (i.e. requires mediation), you can
raise your patch during the Nova meeting and we will try to resolve any
disagreement.

Thirdly, is it in merge conflict with master or are any of the CI tests
failing? Particularly any third-party CI tests that are relevant to the
code you are changing. If you're fixing something that only occasionally
failed before, maybe recheck a few times to prove the tests stay
passing. Without green tests, reviewers tend to move on and look at the
other patches that have the tests passing.

OK, so you have followed all the process (i.e. your patches are getting
advertised via the project's tracking mechanisms), and your patches
either have no reviews, or only positive reviews. Now what?

Have you considered reviewing other people's patches? Firstly,
participating in the review process is the best way for you to
understand what reviewers are wanting to see in the code you are
submitting. As you get more practiced at reviewing it will help you to
write "merge-ready" code. Secondly, if you help review other peoples
code and help get their patches ready for the core reviewers to add a
+2, it will free up a lot of non-core and core reviewer time, so they
are more likely to get time to review your code. For more details,
please see: :ref:`Why do code reviews when I'm not core? <why_plus1>`

Please note, I am not recommending you go to ask people on IRC or via
email for reviews. Please try to get your code reviewed using the above
process first. In many cases multiple direct pings generate frustration
on both sides and that tends to be counter productive.

Now you have got your code merged, lets make sure you don't need to fix
this bug again. The fact the bug exists means there is a gap in our
testing. Your patch should have included some good unit tests to stop
the bug coming back. But don't stop there, maybe its time to add tempest
tests, to make sure your use case keeps working? Maybe you need to set
up a third party CI so your combination of drivers will keep working?
Getting that extra testing in place should stop a whole heap of bugs,
again giving reviewers more time to get to the issues or features you
want to add in the future.

What the Review-Priority label in Gerrit are use for?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A bit of history first. Nova used so called runway slots for multiple cycles.
There was 3 slots, each can be filled with a patch series ready for review for
two weeks at a time. We assumed that cores are focusing on reviewing the series
while it is in the slot. We also assumed that the patch author is available and
quickly fixing feedback while the series is in the slot. Meanwhile other
patches waited in a FIFO queue for a free slot.

Our experience was:

1) It only worked if somebody kept the state of the queue and the slots up to
   date in the etherpad. So it needed a central authority to manage the
   process. This did not scale well.

2) It was as effective as we, cores, are kept it honest and allocated our
   review time on the patches in the slots. Such commitment is hard to get or
   follow up on without being aggressive.

3) Non-cores were not able to tell they were happy with reviewing some change

So the aim of the new review priority process is to be as decentralized amongst
cores as possible. We trust cores that when they mark something as priority
then they also themselves commit to review the patch. We also assume that if a
core reviewed a patch then that core should easily find another core as a
second reviewer when needed. We also want contributors to be able to "ping"
cores asynchronously by asking them to review some changes they saw.

That said, this process doesn't explain how a patch is discovered to be
ready for review. While previously The patch authors were able to
asynchronously beg for reviews by adding their changes to the etherpad, now
they need to find ways to get review attention. For this, we need to understand
first whether this is a problem for contributors or not, so let us know please
if you have issues for asking to get reviews by going to the nova meeting.

Therefore we use the Review-Priority label in Gerrit in the following way:

* Review-Priority is a label with 0, +1 or +2 values.

* A contributor can set the Review-Priority flag to +1 to indicate they will
  want cores to review the patch.

* A core sets the Review-Priority flag to +2 to indicate that they will help
  the author to get the patch merged.

* We expect the contributors setting +1 for a patch that they will continue
  to look at the patch even if a core reviews it so they can then provide
  their own comments or replies.

* We expect that the cores will limit the number of patches marked with +2
  Review-Priority based on their actual review bandwidth

* We expect that cores will check the list of reviews already having
  Review-Priority +2 set by other cores before they mark a new one as such to
  see where they can help first by being the second core.

* There will be a regular agenda point on the weekly meeting where the team
  look at the list of patches with +1 or +2 mark to keep an overall view what
  is happening in nova.

Pros:

* Decentralized

* Each core is responsible of its own commitments

* Review priority information is kept close to the review system

Cons:

* No externally enforced time limit on patches sitting idle with +1
  Review-Priority

* No externally enforced limit on how many things can be a priority at any
  given time.

Process Evolution Ideas
=======================

We are always evolving our process as we try to improve and adapt to the
changing shape of the community. Here we discuss some of the ideas,
along with their pros and cons.

Splitting out the virt drivers (or other bits of code)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Currently, Nova doesn't have strong enough interfaces to split out the
virt drivers, scheduler or REST API. This is seen as the key blocker.
Let's look at both sides of the debate here.

Reasons for the split:

-  can have separate core teams for each repo

   -  this leads to quicker turn around times, largely due to focused
      teams

-  splitting out things from core means less knowledge required to
   become core in a specific area

Reasons against the split:

-  loss of interoperability between drivers

   -  this is a core part of Nova's mission, to have a single API across
      all deployments, and a strong ecosystem of tools and apps built on
      that
   -  we can overcome some of this with stronger interfaces and
      functional tests

-  new features often need changes in the API and virt driver anyway

   -  the new "depends-on" can make these cross-repo dependencies easier

-  loss of code style consistency across the code base
-  fear of fragmenting the nova community, leaving few to work on the
   core of the project
-  could work in subteams within the main tree

TODO - need to complete analysis

Subteam recommendation as a +2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There are groups of people with great knowledge of particular bits of
the code base. It may be a good idea to give their recommendation of a
merge greater strength. In addition, having the subteam focus review efforts
on a subset of patches should help concentrate the nova-core reviews they
get, and increase the velocity of getting code merged.

Ideally this would be done with gerrit user "tags".
There are some investigations by sdague in how feasible it would be to add
tags to gerrit.

Stop having to submit a spec for each release
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As mentioned above, we use blueprints for tracking, and specs to record
design decisions. Targeting specs to a specific release is a heavyweight
solution and blurs the lines between specs and blueprints. At the same
time, we don't want to lose the opportunity to revise existing
blueprints. Maybe there is a better balance?

What about this kind of process:

-  backlog has these folders:

   -  backlog/incomplete - merge a partial spec
   -  backlog/complete - merge complete specs (remove tracking details,
      such as assignee part of the template)
   -  ?? backlog/expired - specs are moved here from incomplete or
      complete when no longer seem to be given attention (after 1 year,
      by default)
   -  /implemented - when a spec is complete it gets moved into the
      release directory and possibly updated to reflect what actually
      happened
   -  there will no longer be a per-release approved spec list

To get your blueprint approved:

-  add it to the next nova meeting

   -  if a spec is required, update the URL to point to the spec merged
      in a spec to the blueprint
   -  ensure there is an assignee in the blueprint

-  a day before the meeting, a note is sent to the ML to review the list
   before the meeting
-  discuss any final objections in the nova-meeting

   -  this may result in a request to refine the spec, if things have
      changed since it was merged

-  trivial cases can be approved in advance by a nova-driver, so not all
   folks need to go through the meeting

This still needs more thought, but should decouple the spec review from
the release process. It is also more compatible with a runway style
system, that might be less focused on milestones.

Runways
~~~~~~~

Runways are a form of Kanban, where we look at optimising the flow
through the system, by ensuring we focus our efforts on reviewing a
specific subset of patches.

The idea goes something like this:

-  define some states, such as: design backlog, design review, code
   backlog, code review, test+doc backlog, complete
-  blueprints must be in one of the above state

   -  large or high priority bugs may also occupy a code review slot

-  core reviewer member moves item between the slots

   -  must not violate the rules on the number of items in each state
   -  states have a limited number of slots, to ensure focus
   -  certain percentage of slots are dedicated to priorities, depending
      on point in the cycle, and the type of the cycle, etc

Reasons for:

-  more focused review effort, get more things merged more quickly
-  more upfront about when your code is likely to get reviewed
-  smooth out current "lumpy" non-priority feature freeze system

Reasons against:

-  feels like more process overhead
-  control is too centralised

Replacing Milestones with SemVer Releases
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can deploy any commit of Nova and upgrade to a later commit in that
same release. Making our milestones versioned more like an official
release would help signal to our users that people can use the
milestones in production, and get a level of upgrade support.

It could go something like this:

-  14.0.0 is milestone 1
-  14.0.1 is milestone 2 (maybe, because we add features, it should be
   14.1.0?)
-  14.0.2 is milestone 3
-  we might do other releases (once a critical bug is fixed?), as it
   makes sense, but we will always be the time bound ones
-  14.0.3 two weeks after milestone 3, adds only bug fixes (and updates
   to RPC versions?)

   -  maybe a stable branch is created at this point?

-  14.1.0 adds updated translations and co-ordinated docs

   -  this is released from the stable branch?

-  15.0.0 is the next milestone, in the following cycle

   -  not the bump of the major version to signal an upgrade
      incompatibility with 13.x

We are currently watching Ironic to see how their use of semver goes,
and see what lessons need to be learnt before we look to maybe apply
this technique during M.

Feature Classification
~~~~~~~~~~~~~~~~~~~~~~

This is a look at moving forward the :doc:`support matrix effort
</user/support-matrix>`.

The things we need to cover:

-  note what is tested, and how often that test passes (via 3rd party
   CI, or otherwise)

   -  link to current test results for stable and master (time since
      last pass, recent pass rate, etc)
   -  TODO - sync with jogo on his third party CI audit and getting
      trends, ask infra

-  include experimental features (untested feature)
-  get better at the impact of volume drivers and network drivers on
   available features (not just hypervisor drivers)

Main benefits:

-  users get a clear picture of what is known to work
-  be clear about when experimental features are removed, if no tests
   are added
-  allows a way to add experimental things into Nova, and track either
   their removal or maturation

.. _PTL: https://governance.openstack.org/tc/reference/projects/nova.html
