The facets of the OpenStack integrated release
In a recent Technical Committee update on the OpenStack blog, I explained how the OpenStack "integrated release" concept, due to its binary nature, ended up meaning all sorts of different things to different people. That is the main reason why we want to deconstruct its various meanings into a set of tags that can be independently applied to projects, in order to more accurately describe our project ecosystem.
In this blogpost, I'll look into the various meanings the "integrated release" ended up having in our history, and see how we can better convey that information through separate tags.
The original meaning of "integrated release" is that all the projects in it are released together on the same date, at the end of our development cycles.
I recently proposed a tag ("release:at-6mo-cycle-end") to describe projects that commit to producing a release at the end of our development cycles, which I think will cover that facet.
Very quickly, the "integrated release" also described projects which had their release managed by the OpenStack Release Management team. This team sets up processes (mostly a Feature Freeze deadline and a release candidate dance) to maximize the chances that managed projects would release on a pre-announced date, and that none of the managed projects would end up delaying the end release date.
Projects would be added to incubation and when we thought they were ready to follow those processes without jeopardizing the "integrated release" for existing projects, they would get added to be the next release.
That is a separate facet from the previous one, so I proposed a separate tag ("release:managed") to describe projects that happen to still be handled by the Release Management team.
As we introduced complex code gating in OpenStack Infrastructure, the "integrated release" concept grew another facet: it would also mean that projects changes are tested against one another master branches. That way we ensure that changes in project B don't break project A. This is rather neat for a tightly-coupled set of projects. But this may be a bit overkill for projects higher in the stack that just consume public APIs. Especially when non-deterministic test errors in project A prevent changes from landing in B.
We need to revise how to split co-gating in meaningful groups. This work is led by Sean Dague. Once it is completed, I expect us to convey the information on what is actually tested together using tags as well.
Supported by OpenStack horizontal efforts
From there, the "integrated release" naturally evolved to also being the set of projects that horizontal efforts (such as Documentation, QA, stable branch maintenance, Vulnerability management, Translations...) would focus their work on. Being part of the "integrated release" ensured that you would get fully supported by those horizontal teams.
That didn't scale that well, though. The documentation team was the first to exhaust their limited resources, and started to move to a model where they would not directly write all the docs for all the integrated projects. Since then, all horizontal teams decided to gradually move to the same model, where they would directly handle a number of projects (or none), but provide tooling, mentoring and support for all the others.
It's still valuable information to know which project happens to be directly handled by which horizontal effort, and which project ends up having security support or basic docs. So we'll introduce tags in the future to accurately describe this facet.
The base features
Going downhill, the "integrated release" started to also mean the base features you can rely on being present when people say they deployed "OpenStack". That was a bit at odds with the previous facets though: why would all co-gating projects with a coordinated release necessarily be essential ? And indeed, the integrated release grew beyond "base" features (like Keystone) to include obviously optional projects (like Sahara or Ceilometer).
I personally think our users would still benefit from a description of what layer each project belongs to: is it providing base IaaS compute functionality, or is it relying on that being present ? This is not a consensual view though, as some people object to all proposals leading to any type of ranking within OpenStack projects.
At that point, the "integrated release" was "the OpenStack release", and things outside of it were "not OpenStack".
This obviously led to more pressure to add more projects in it. But when the OpenStack governance (previously under a single Project Policy Board banner) was split between the Technical Committee and the Foundation Board, the former retained control over the "integrated release" contents, and the latter took control of trademark usage. This created tension over that specific facet.
Defcore was created to solve this problem, by defining the criteria to apply to various trademark programs. When asked to provide a set of projects (or rather, as set of sections of code) to apply the trademark on, the Technical Committee answered with the only concept it had (you guessed it, "the integrated release" again).
In the tags world, when asked for a set of projects to apply a particular trademark program to, the Technical Committee shall be able to provide a finer-grained answer, by defining a specific tag for each question.
Further downhill, "integrated release" also started to mean "stable". Once published in such a release, a project would not remove a feature without proper discussion, notice, and deprecation period. That was yet another facet of the now-bloated "integrated release" concept.
The issue is, all projects were not able to commit to the same stability rules. One would never deprecate an existing feature, while one would rip its API off over the course of two development cycles. One size didn't fit all.
In the tags world, my view is that Ops and devs, working together, should define various stability levels and the rules that apply for each. Then each project can pick the tag corresponding to the stability level they can commit to.
Last but not least, at one point people started to assume that projects in the "integrated release" were obviously mature. They were all in widespread usage, enterprise-ready, carrier-grade, service-provider-class, web-scale. The reality is, this facet is also complex: some projects are, and some projects are less, and some projects aren't. So we need to describe the various maturity styles and levels, and inform our users of each project real status.
It's difficult to describe maturity objectively though. I intend to discuss that topic with the ones that are the best placed to accurately describe it: the OpenStack operators gathered at the Ops Summit next week.