[openstack-dev] [nova] RFC - using Gerrit for Nova Blueprint review & approval

Tim Bell Tim.Bell at cern.ch
Fri Mar 7 19:50:04 UTC 2014

The recent operator gathering (https://etherpad.openstack.org/p/operators-feedback-mar14) concluded a similar proposal, based on Blueprint-on-Blueprints (BoB for short).

The aim was that operators of production OpenStack clouds should engage to give input at an early stage

- Raising concerns at the specification stage will be much more productive than after the code is written
- Operators may not have the in-depth python skills for productive participation in the later stages of the review
- Appropriate credit can also be granted to those people refining the requirements/specification process. Spotting an issue before coding starts is a major contribution.

The sort of items we were worrying about were:

        Health check/http ping
        object state/flow

We also need to review the weighting. A blueprint should not be indefinitely postponed due to a differing view on requirements between new function and the ability to run the existing environments.


> -----Original Message-----
> From: Murray, Paul (HP Cloud Services) [mailto:pmurray at hp.com]
> Sent: 07 March 2014 14:57
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [nova] RFC - using Gerrit for Nova Blueprint review & approval
> The principle is excellent, I think there are two points/objectives worth keeping in mind:
> 1. We need an effective way to make and record the design decisions 2. We should make the whole development process easier
> In my mind the point of the design review part is to agree up front something that should not be over-turned (or is hard to over-turn)
> late in patch review. I agree with others that a patch should not be blocked (or should be hard to block) because the reviewer
> disagrees with an agreed design decision. Perhaps an author can ask for a -2 or -1 to be removed if they can point out the agreed
> design decision, without having to reopen the debate.
> I also think that blueprints tend to have parts that should be agreed up front, like changes to apis, database migrations, or
> integration points in general. They also have parts that don't need to be agreed up front, there is no point in a heavyweight process
> for everything. Some blueprints might not need any of this at all. For example, a new plugin for the filter scheduler might no need a
> lot of design review, or at least, adding the design review is unlikely to ease the development cycle.
> So, we could use the blueprint template to identify things that need to be agreed in the design review. These could include anything
> the proposer wants agreed up front and possibly specifics of a defined set of integration points. Some blueprints might have nothing
> to be formally agreed in design review. Additionally, sometimes plans change, so it should be possible to return to design review.
> Possibly the notion of a design decision could be broken out form a blueprint in the same way as a patch-set? maybe it only makes
> sense to do it as a whole? Certainly design decisions should be made in relation to other blueprints and so it should be easy to see
> that there are two blueprints making related design decisions.
> The main point is that there should be an identifiable set of design decisions that have reviewed and agreed that can also be found.
> **The reward for authors in doing this is the author can defend their patch-set against late objections to design decisions.** **The
> reward for reviewers is they get a way to know what has been agreed in relation to a blueprint.**
> On another point...
> ...sometimes I fall foul of writing code using an approach I have seen in the code base, only to be told it was decided not to do it that
> way anymore. Sometimes I had no way of knowing that, and exactly what has been decided, when it was decided, and who did the
> deciding has been lost. Clearly the PTL and ML do help out here, but it would be helpful if such things were easy to find out. These
> kinds of design decision should be reviewed and recorded.
> Again, I think it is excellent that this is being addressed.
> Paul.
> -----Original Message-----
> From: Sean Dague [mailto:sean at dague.net]
> Sent: 07 March 2014 12:01
> To: OpenStack Development Mailing List (not for usage questions)
> Subject: Re: [openstack-dev] [nova] RFC - using Gerrit for Nova Blueprint review & approval
> On 03/07/2014 06:30 AM, Thierry Carrez wrote:
> > Sean Dague wrote:
> >> One of the issues that the Nova team has definitely hit is Blueprint
> >> overload. At some point there were over 150 blueprints. Many of them
> >> were a single sentence.
> >>
> >> The results of this have been that design review today is typically
> >> not happening on Blueprint approval, but is instead happening once
> >> the code shows up in the code review. So -1s and -2s on code review
> >> are a mix of design and code review. A big part of which is that
> >> design was never in any way sufficiently reviewed before the code started.
> >>
> >> In today's Nova meeting a new thought occurred. We already have
> >> Gerrit which is good for reviewing things. It gives you detailed
> >> commenting abilities, voting, and history. Instead of attempting (and
> >> usually
> >> failing) on doing blueprint review in launchpad (or launchpad + an
> >> etherpad, or launchpad + a wiki page) we could do something like follows:
> >>
> >> 1. create bad blueprint
> >> 2. create gerrit review with detailed proposal on the blueprint 3.
> >> iterate in gerrit working towards blueprint approval 4. once approved
> >> copy back the approved text into the blueprint (which should now be
> >> sufficiently detailed)
> >>
> >> Basically blueprints would get design review, and we'd be pretty sure
> >> we liked the approach before the blueprint is approved. This would
> >> hopefully reduce the late design review in the code reviews that's
> >> happening a lot now.
> >>
> >> There are plenty of niggly details that would be need to be worked
> >> out
> >>
> >>  * what's the basic text / template format of the design to be
> >> reviewed (probably want a base template for folks to just keep things consistent).
> >>  * is this happening in the nova tree (somewhere in docs/ - NEP (Nova
> >> Enhancement Proposals), or is it happening in a separate gerrit tree.
> >>  * are there timelines for blueprint approval in a cycle? after which
> >> point, we don't review any new items.
> >>
> >> Anyway, plenty of details to be sorted. However we should figure out
> >> if the big idea has support before we sort out the details on this one.
> >>
> >> Launchpad blueprints will still be used for tracking once things are
> >> approved, but this will give us a standard way to iterate on that
> >> content and get to agreement on approach.
> >
> > Sounds like an interesting experiment, and a timely one as we figure
> > out how to do blueprint approval in the future with StoryBoard.
> >
> > I'm a bit skeptical that can work without enforcing that changes
> > reference at least a bug or a blueprint, though. People who were too
> > lazy to create a single-sentence blueprint to cover for their feature
> > will definitely not go through a Gerrit-powered process, so the
> > temptation to fly your smallish features below the radar ("not worth
> > this whole blueprint approval thing") and just get them merged will be
> > high. I fear it will overall result in work being less tracked, rather
> > than more tracked.
> >
> > FWIW we plan to enforce a bug reference / blueprint reference in
> > changes with StoryBoard, but it comes with autocreation of missing
> > bugs/blueprints (from the commit message) to lower the developer hassle.
> >
> > That being said, don't let my skepticism go into the way of your
> > experimentation. We definitely need to improve in this area. I'd like
> > to have a cross-project session on feature planning/tracking at the
> > Design Summit, where we can brainstorm more ideas around this.
> Honestly, right now we're not trying to fix all things (or enforce all things). We're trying to fix a very specific issue that because we are
> tool-failing on blueprint approval, as it's entirely impossible to have a detailed conversation in launchpad, we're failing open with a
> bunch of approved and targeted blueprints that no one understands what they are.
> I want StoryBoard more than anyone else. However future Puppies and Unicorns don't fix real problems right now. With the tools
> already at our disposal, just using them a different way, I think we can fix some real problems. I think, more importantly, we're going
> to discover a whole new class of problems because we're not blocked on launchpad.
> And the fact that the Nova team and the Ops team came up with the same idea, independently, within a week of each other, is a
> reasonable indication that it's worth trying. Because it seriously can't be worse than the current model. :)
> 	-Sean
> --
> Sean Dague
> Samsung Research America
> sean at dague.net / sean.dague at samsung.com
> http://dague.net
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