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Architecture Working Group

Mission

Be the recognized forum of expertise on the design and architecture of OpenStack and provide guidance and resources to the Technical Committee and the entire OpenStack community on architectural matters.

This group is be open to all volunteers who are interested in participating in OpenStack-wide design discussions.

Also note that this is an advisory group intended to gather information and produce recommendations. No new authority for enforcing those is to be conferred onto this group, however accepted recommendations will be expected to be followed for new work whenever possible.

Scope

  • Document the existing architecture and relationship of OpenStack projects.
  • Provide information and guidance to the TC and the OpenStack community on architectural matters.
  • Provide productive spaces for architects to share their designs and gain support across projects to move forward with, coordinate, and implement architectural decisions.
  • Start with a limited scope in order to refine the group processes and be able to achieve visible results (positive or negative) within the upcoming Ocata release cycle.

Communication

Deliverables

  • [details tbd]

How To Contribute

Topics

The WG maintains a backlog of topics in the repo under backlog/. Additions to the backlog should be proposed using Gerrit. Approval for addition is concerned primarily with the proposal fitting into the scope of the WG.

  • A topic background document should be proposed to the WG repo under backlog/
  • The proposal will be held for review for a minimum of one week to allow time for dicussion regarding its fitness for the scope of the WG.
  • The proposal should also be added to an upcoming IRC meeting agenda to allow the proposer to make a pitch and answer questions.
  • Proposals that do not receive objections after the review period will be considered approved as in-scope and merged into the backlog.
  • The WG will move proposals from the backlog to the active/ work area as it chooses to work on them.

The background document should be sufficient to describe the topic and use cases or other reasons it should be considered, such as how it would improve OpenStack as a whole or solve specific use cases.

Participation

Participation in the Architecture Working Group is voluntary and defined by those who attend the meetings and contribute proposals, reviews and effort into the group activities. There is a core review group (seeded with volunteers at early meetings) that has the ability to commit changes to the WG Git repo. As with most of OpenStack, membership of that group is merit-based with participation and other contributions being considered.

Background

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."

Problem description

For each individual project, design 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 debugging, 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 , including dlm, taskflow, tooz, service discovery, state machines, glance tasks, messaging patterns, database patterns, etc. etc. Often 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 on the diagram below, but we all know it really isn't.

image

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 build consensus around changes that would help us get to the point of gathering the necessary will and capability to enact these efforts.

The need for attention ranges from the above project interaction level up to higher-level questions such as 'What other OpenStack services can any particular service assume to be available?'