[openstack-dev] [all] Proposal: Architecture Working Group
Fox, Kevin M
Kevin.Fox at pnnl.gov
Mon Jun 20 20:39:41 UTC 2016
Some other topics:
* Rolling upgrades - For example, I haven't figured out a way to safely drain an rpc based service rather then just shooting it and hoping things go well... Is it safe? This safety code should be built into them all consistently.
* How to get events to users in a usable way. OpenStack Service X event -> Some system that duplicates the event stream based on requests from users -> Multiple Zaqar Queues? -> User? Can this co-exist with Horizon using it for updating its UI without polling?
* The state of guest agents is abysmal. Each service uses a different way to talk between controller and vm, and each has its own problems and operators need to figure out workarounds for all. Its really painful. We need something like a unified guest agent that gets the logic right, and is plugable.
From: Clint Byrum [clint at fewbar.com]
Sent: Monday, June 20, 2016 11:31 AM
Subject: Re: [openstack-dev] [all] Proposal: Architecture Working Group
Excerpts from Joshua Harlow's message of 2016-06-17 15:33:25 -0700:
> Thanks for getting this started Clint,
> I'm happy and excited to be involved in helping try to guide the whole
> ecosystem together (it's also why I like being in oslo) to a
> architecture that is more cohesive (and is more of something that we can
> say to our current or future children that we were all involved and
> proud to be involved in creating/maturing...).
> At a start, for said first meeting, any kind of agenda come to mind, or
> will it be more a informal gathering to start (either is fine with me)?
I've been hesitant to fill this in too much as I'm still forming the
idea, but here are the items I think are most compelling to begin with:
* DLM's across OpenStack -- This is already under way, but it seems to
have fizzled out. IMO that is because there's no working group who
owns it. We need to actually write some plans.
* Messaging patterns -- There was a recent discussion about nuances in
oslo.messaging's implementation that vary driver to driver. I'd like to
make sure we have all of the ways messaging is used written down and
make sure groups have guidance on how each one should (or shouldn't)
be used, including documentation of anti-patterns, and a plan for
simplifying communication between processes in OpenStack where
* True Microservices -- OpenStack's services are heavily
interdependent. It makes it hard for an engineer to make an impact
without becoming an expert on all of them, and it also leads to a heavy
burden on operators and QA as they end up having to debug the system
as a whole. We should write down how the system is intertwined now, and
develop plans for unwinding that and allowing each service to stand on
its own, including having stronger testing in isolation. (This includes
exploring the thought that nova-compute could become its own project
that all of the other things communicate with over well defined APIs).
These could keep a small group of architects and engineers busy for a
year or more. I'm sure others have things they'd like to design and
improve in OpenStack at this level.
Once we have broad agreement on such a group, and perhaps some guidance
from the TC, we can propose an agenda and prioritize efforts as part of
the first few meetings.
> Clint Byrum wrote:
> > ar·chi·tec·ture
> > ˈärkəˌtek(t)SHər/
> > noun
> > noun: architecture
> > 1.
> > the art or practice of designing and constructing buildings.
> > synonyms:building design, building style, planning, building, construction;
> > formalarchitectonics
> > "modern architecture"
> > the style in which a building is designed or constructed, especially with regard to a specific period, place, or culture.
> > plural noun: architectures
> > "Victorian architecture"
> > 2.
> > the complex or carefully designed structure of something.
> > "the chemical architecture of the human brain"
> > the conceptual structure and logical organization of a computer or computer-based system.
> > "a client/server architecture"
> > synonyms:structure, construction, organization, layout, design, build, anatomy, makeup;
> > informalsetup
> > "the architecture of a computer system"
> > Introduction
> > =========
> > OpenStack is a big system. We have debated what it actually is ,
> > and there are even t-shirts to poke fun at the fact that we don't have
> > good answers.
> > But this isn't what any of us wants. We'd like to be able to point
> > at something and proudly tell people "This is what we designed and
> > implemented."
> > And for each individual project, that is a possibility. Neutron can
> > tell you they designed how their agents and drivers work. Nova can
> > tell you that they designed the way conductors handle communication
> > with API nodes and compute nodes. But when we start talking about how
> > they interact with each other, it's clearly just a coincidental mash of
> > de-facto standards and specs that don't help anyone make decisions when
> > refactoring or adding on to the system.
> > Oslo and cross-project initiatives have brought some peace and order
> > to the implementation and engineering processes, but not to the design
> > process. New ideas still start largely in the project where they are
> > needed most, and often conflict with similar decisions and ideas in other
> > projects [dlm, taskflow, tooz, service discovery, state machines, glance
> > tasks, messaging patterns, database patterns, etc. etc.]. Often times this
> > creates a log jam where none of the projects adopt a solution that would
> > align with others. Most of the time when things finally come to a head
> > these things get done in a piecemeal fashion, where it's half done here,
> > 1/3 over there, 1/4 there, and 3/4 over there..., which to the outside
> > looks like<architecture> chaos, because that's precisely what it is.
> > And this isn't always a technical design problem. OpenStack, for instance,
> > isn't really a micro service architecture. Of course, it might look like
> > that in diagrams , but we all know it really isn't. The compute node is
> > home to agents for every single concern, and the API interactions between
> > the services is too tightly woven to consider many of them functional
> > without the same lockstep version of other services together. A game to
> > play is ask yourself what would happen if a service was isolated on its
> > own island, how functional would its API be, if at all. Is this something
> > that we want? No. But there doesn't seem to be a place where we can go
> > to actually design, discuss, debate, and ratify changes that would help
> > us get to the point of gathering the necessary will and capability to
> > enact these efforts.
> > Maybe nova-compute should be isolated from nova, with an API that
> > nova, cinder and neutron talk to. Maybe we should make the scheduler
> > cross-project aware and capable of scheduling more than just nova
> > instances. Maybe we should have experimental groups that can look at how
> > some of this functionality could perhaps be delegated to non-openstack
> > projects. We hear that Mesos, for example to help with the scheduling
> > aspects, but how do we discuss these outside hijacking threads on the
> > mailing list? These are things that we all discuss in the hallways
> > and bars and parties at the summit, but because they cross projects at
> > the design level, and are inherently a lot of social and technical and
> > exploratory work, Many of us fear we never get to a place of turning
> > our dreams into reality.
> > So, with that, I'd like to propose the creation of an Architecture Working
> > Group. This group's charge would not be design by committee, but a place
> > for architects to share their designs and gain support across projects
> > to move forward with and ratify architectural decisions. That includes
> > coordinating exploratory work that may turn into being the base of further
> > architectural decisions for OpenStack. I would expect that the people
> > in this group would largely be senior at the companies involved and,
> > if done correctly, they can help prioritize this work by advocating for
> > people/fellow engineers to actually make it 'real'. This will give weight
> > to specs and implementation changes to make these designs a reality,
> > and thus I believe this group would do well to work closely with the
> > Oslo Team, where many of the cross-cutting efforts will need to happen.
> > How to get involved
> > ===================
> > If the idea is well received, I'd like to propose a bi-weekly IRC
> > meeting at a time convenient for the most interested individuals. I'd
> > also like to see a #openstack-architecture channel for gathering real
> > time chatter about architecture, and an architecture tag. Finally, I'd
> > like to see this group collaborate on direct work using the existing
> > openstack-specs repository.
> > In closing
> > ==========
> > First, thanks for reading this whole message and considering this
> > evolution of our processes. I am excited to begin this discussion, and
> > hope that we can arrive at a plan quickly that leads to us all being
> > able to discuss the architecture of OpenStack productively.
> > Also, thanks to those of you who helped me review and edit this document.
> >  http://lists.openstack.org/pipermail/openstack-dev/2016-May/095452.html
> >  http://docs.openstack.org/admin-guide/_images/openstack-arch-kilo-logical-v1.png
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